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თქვენი ღონისძიების ჩასატარებლად ეროვნულ სამეცნიერო ბიბლიოთკაში, გთხოვთ, შეავსოთ სააპლიკაციო ფორმა და გადგმოგზავნოთ ელექტრონულ მისამართზე: infopr@sciencelib.ge

მსოფლიო სამეცნიერო სიახლეები

Health agency reveals scourge of fake drugs in developing world

NatureNews - free content - 1 საათი 45 წთ-ს წინ

WHO data suggest around 10% of medications in poorer countries are fraudulent or substandard.

Nature News doi: 10.1038/nature.2017.23051

China to roll back regulations for traditional medicine despite safety concerns

NatureNews - free content - 1 საათი 45 წთ-ს წინ

Scientists fear plans to abandon clinical trials of centuries-old remedies will put people at risk.

Nature 551 552 doi: 10.1038/nature.2017.23038

Rise in malaria cases sparks fears of a resurgence

NatureNews - free content - 1 საათი 45 წთ-ს წინ

Progress in the fight against a curable disease that kills hundreds of thousands of children has stalled, according to the World Health Organization.

Nature News doi: 10.1038/nature.2017.23046

How an underwater sensor network is tracking Argentina's lost submarine

NatureNews - free content - 1 საათი 45 წთ-ს წინ

An expert from a nuclear-test-monitoring system explains how his team is trying to help in the search for the ARA San Juan .

Nature News doi: 10.1038/nature.2017.23041

Zimbabwe’s researchers hope political change will revitalize science

NatureNews - free content - 1 საათი 45 წთ-ს წინ

Academics optimistic that the end of Robert Mugabe’s authoritarian rule could boost research and international collaboration.

Nature News doi: 10.1038/nature.2017.23039

AI-controlled brain implants for mood disorders tested in people

NatureNews - free content - 1 საათი 45 წთ-ს წინ

Researchers funded by the US military are developing appliances to record neural activity and automatically stimulate the brain to treat mental illness.

Nature 551 549 doi: 10.1038/nature.2017.23031

Lightning makes new isotopes

NatureNews - free content - 1 საათი 45 წთ-ს წინ

Physicists show that thunderstorms trigger nuclear reactions in the atmosphere.

Nature News doi: 10.1038/nature.2017.23033

Hungary rewards highly cited scientists with bonus grants

NatureNews - free content - 1 საათი 45 წთ-ს წინ

Some top researchers prosper in Hungary as country tries to improve its international standing in science.

Nature 551 425 doi: 10.1038/551425a

Neural ‘tug-of-war’ may explain Fragile X learning issues

Futurity.org - 1 საათი 54 წთ-ს წინ

Mice with the genetic defect that causes Fragile X syndrome (FXS) learn and remember normally, but show an inability to learn new information that contradicts what they initially learned, a new study shows. FXS is the most common genetic cause of intellectual disability and autism.

“These findings suggest that neural circuits in FXS may be fundamentally intact but improperly tuned, which results in inflexibility in gaining certain types of knowledge,” says André Fenton, a professor in the Center for Neural Science at New York University and senior author of the paper, which appears in PLOS Biology.

“We now have a better understanding of a cognitive deficit that is characteristic of FXS—excessive recollection of the information that was once accurate and an inability to process corrective material,” Fenton says.

The study focuses on the hippocampus—the part of the brain crucial for memory, especially about space, which requires both encoding and remembering information.

However, because the same neurons are active in both encoding and remembering, it’s unknown what neural events control whether hippocampal neurons are encoding current experience into memory or recollecting information from memory. This dynamic is one of the keys to better understanding FXS, which impairs use of memory in multiple ways.

To explore this, first the scientists had to uncover an electrophysiological “signature of recollection” in the hippocampus—a mapping that pinpointed whether these neurons are encoding current experience into memory or recollecting information from memory.

This resulted in two primary findings.

Specifically, they found that encoding and recollection are the result of a neural “tug-of-war” between two distinctive types of rhythmic neural synaptic activity within the hippocampus.

Fragile X discovery may clarify root cause of symptoms

Notably, encoding occurs when fast rhythmic activity overwhelms slower rhythmic activity; by contrast, recollection occurs when the slower rhythm dominates the medium rhythm.

The second finding, which sheds new light on FXS, shows that FXS mice have an excessive amount of the slow rhythm.

FXS hippocampus neurons are normal, and, as a result, FXS mice can learn and remember in the ways other mice do. Due to excessive dominance of the slow rhythm in FXS mice, however, they fail to learn new information that specifically contradicts what they initially learned.

In other words, the neural tug-of-war is too often won by the slower rhythm, preventing normal adaptive flexibility of cognitive function.

“This cognitive behavioral inflexibility is characteristic of FXS and autism and now is explained by excessive recollection of the formerly correct but currently incorrect information that is stored in the hippocampus,” Fenton says.

Treatment for Fragile X could target this protein

Dino Dvorak, a postdoctoral fellow in NYU’s Center for Neural Science is a coauthor of the study. The Simons Foundation and the National Institutes of Health supported the work.

Source: New York University

The post Neural ‘tug-of-war’ may explain Fragile X learning issues appeared first on Futurity.

Faster, more accurate HIV test just needs spit

Futurity.org - 1 საათი 57 წთ-ს წინ

A new HIV test combines the convenience of spitting in a cup with the reliability of blood tests, researchers report.

“The earlier you can detect, the better, because people can infect other people.”

Currently, public health officials have a tough choice to make when it comes to screening people for HIV: administer a reliable blood test that can detect infections early on, but that few people will volunteer for, or give people a convenient test using saliva that is less reliable during the first stages of infection. The new test could change that.

“The earlier you can detect, the better, because people can infect other people,” says Carolyn Bertozzi, professor in the School of Humanities and Sciences at Stanford University and a professor of chemistry.

“Every day that goes by that a person’s behavior is not modified based on their HIV status is a day that they could be infecting other people, especially for young people,” says Bertozzi, who is also a faculty fellow of Stanford ChEM-H and a member of Stanford Bio-X.

Blood vs. spit

By far the most common way to test for HIV infection is to look in a blood sample for antibodies, proteins that the immune system custom-builds to attack the virus and fight back against infection. That test is far more convenient than a direct search for the virus, in part because antibodies are relatively abundant in the bloodstream after the early stages of infection.

Yet there is a major drawback, especially for public health officials and researchers who want—and sometimes need—to get a lot of people tested quickly to help contain the spread of the disease: needles.

“There’s a lot of populations you just can’t reach out to by blood tests,” says Cheng-ting “Jason” Tsai, the lead author on the new paper and a graduate student in Bertozzi’s lab. “But if you were to do oral fluid, then all of sudden you open up a brand new population that was not otherwise accessible to you.”

But oral fluid tests have their own problems. While there are HIV antibodies in saliva, they do not accumulate at the levels they do in blood, or at the same speed—meaning that there just aren’t that many present, especially early on.

By the time oral fluid tests can reliably detect HIV, Bertozzi says, “you’ve waited a long time”—and in that time, the infection could spread.

‘Purposefully low tech’

The team’s job, then, was to figure out how to make it easier to detect the small amount of antibodies present in the saliva of someone with HIV. To do that, they took an indirect approach. Instead of looking for the antibodies themselves, they looked for what antibodies could do.

The team took advantage of a key feature of antibodies—they have two arms, each of which easily latches onto a virus like HIV. They took bits of HIV and attached them to one or the other half of a piece of DNA. They then added the modified HIV bits into the saliva sample.

HIV tests in primary care can save UK money

If the sample contained HIV antibodies, their two arms would grab hold of the tagged HIV, bringing the two halves of the DNA together into a continuous strand. Once the DNA piece is made whole it is easy to detect using standard lab techniques.

That can all be done without requiring a blood sample or much technology to process the samples.

“It’s purposefully low tech,” Bertozzi says.

Although the researchers say it will take more studies to confirm the results, the first experiments show that it works well: the test correctly diagnosed 22 people who took part in an Alameda County screening effort, each of whom had tested positive for HIV using other methods. Importantly, the test did not falsely detect HIV in the 22 additional HIV-negative participants.

It may also work earlier compared to other saliva tests, although not earlier than existing blood tests. In a set of eight samples that had produced mixed results with the current standard saliva test, six turned up positive with the new HIV test, and one of those was confirmed using a blood test. Although those results are preliminary, they suggest that the new test is more sensitive and could pick up HIV infection sooner than others.

“Our hope is that we can get an earlier read than the present oral test because the sensitivity is better,” Bertozzi says.

How HIV ‘hacks’ cells to spread itself

Beyond HIV, she and Tsai says, the same principles may be useful for allergy testing and screening for typhoid and tuberculosis infection. The team is also investigating the method as a way to test the efficacy of measles vaccination efforts, Bertozzi says.

The researchers report their findings in the Proceedings of the National Academy of Sciences.

Funding for the research came from grants from the Stanford Predictive and Diagnostics Accelerator, the National Science Foundation, and the National Institutes of Health.

Source: Stanford University

The post Faster, more accurate HIV test just needs spit appeared first on Futurity.

‘Legos of life’ stack together to build proteins

Futurity.org - 2 საათი 9 წთ-ს წინ

After smashing and dissecting nearly 10,000 proteins to understand their component parts, scientists have discovered the “Legos of life”—four core chemical structures that can be stacked together to build the myriad proteins inside every organism.

The four building blocks make energy available for humans and all other living organisms, according to a new study describing the discovery, which appears in the Proceedings of the National Academy of Sciences.

The findings could lead to applications of these stackable, organic building blocks for biomedical engineering and therapeutic proteins and the development of safer, more efficient industrial and energy catalysts—proteins and enzymes that, like tireless robots, can repeatedly carry out chemical reactions and transfer energy to perform tasks.

“We don’t have a fossil record of what proteins looked like 4 billion years ago, so we have to take what we have today and start walking backwards…”

“Understanding these parts and how they are connected to each other within the existing proteins could help us understand how to design new catalysts that could potentially split water, fix nitrogen, or do other things that are really important for society,” says study coauthor Paul G. Falkowski, a professor who leads the Environmental Biophysics and Molecular Ecology Laboratory at Rutgers University–New Brunswick.

The research was carried out on computers, using data on the 3D atomic structures of 9,500 proteins in the RCSB Protein Data Bank, based at Rutgers, a source of information about how proteins work and evolve.

“We don’t have a fossil record of what proteins looked like 4 billion years ago, so we have to take what we have today and start walking backwards, trying to imagine what these proteins looked like,” says Vikas Nanda, senior author of the study and an associate professor of biochemistry and molecular biology at Rutgers’ Robert Wood Johnson Medical School.

“The study is the first time we’ve been able to take something with thousands of amino acids and break it down into reasonable chunks that could have had primordial origins,” says Nanda.

Certain proteins stay ‘relaxed’ while floating inside cells

The identification of four fundamental building blocks for all proteins is just a beginning. Nanda says future research may discover five or 10 more building blocks that serve as biological Legos.

“Now we need to understand how to put these parts together to make more interesting functional molecules. That’s the next grand challenge,” he explains.

Hagai Raanana, a postdoctoral associate in the Environmental Biophysics and Molecular Ecology Program is the study’s lead author. Doctoral student Douglas H. Pike and postdoctoral associate Eli K. Moore are also coauthors.

Source: Rutgers University

The post ‘Legos of life’ stack together to build proteins appeared first on Futurity.

Math model simulates growing melanoma

Futurity.org - 2 საათი 14 წთ-ს წინ

Cancer cells’ ability to tolerate crowded conditions may be key to understanding how tumors form and grow, applying a mathematical model to cancer cell growth reveals.

The model can replicate patterns of melanoma cell growth seen in laboratory experiments by controlling the “exclusion area”—the amount of space required—around two types of simulated cells as they grow and spread.

“When our collaborators grew melanoma cancer cells in a mixed culture with normal cells,” says Yuri Suhov, professor of mathematics at Penn State and an author of the paper, “the cancer cells grew and spread more quickly, forming clusters of melanoma cells surrounded by non-cancer cells.

melanoma model animationSimulated cancer cells (black) grow and form clusters surrounded by non-cancer cells (yellow) replicating experimental results. The simulations, based on a modification of the Widom-Rowlinson model, may give researchers clues to the factors that allow tumors to form. (Credit: Penn State)

“This clustered pattern of melanoma cells resembled two-dimensional proto-tumors, so we were interested in modeling this pattern formation in order to understand what about the cancer cells allows them to grow in this way,” Suhov says. “Melanoma is a skin cancer of a relatively rare occurrence. However, it is one of most lethal forms of cancer characterized by a high potential for metastasis, which makes it crucial to understand the dynamics of the tumor growth and develop methods for early detection”

The researchers applied a modification of the Widom-Rowlinson model—a mathematical model that has been used in contexts ranging from theoretical chemistry to sociology—to try to determine what factors explained the pattern of cell growth seen in the laboratory experiments.

Their model simulates the growth of two cell types that initially are evenly mixed and evenly spaced across a grid. By varying parameters of the model, the researchers can control the rate at which each cell type replicates, dies, and migrates, as well as the required exclusion area around the cells.

“By altering the exclusion distance between the two cell types in the simulations, we were able to replicate the clustered patterns seen in the experiments,” says Izabella Stuhl, visiting assistant professor in mathematics at Penn State and another author of the paper.

“The cell type with the narrower exclusion area was more tolerant of dense conditions and formed patterns almost identical to the clusters of melanoma cells seen in the laboratory experiments. This suggests that a reduction in ‘contact inhibition’—a known factor that stops cells from replicating when they bump into other cells—may be what allows tumors to form,” Stuhl says.

In the course of their work, the researchers first made predictions based on the mathematical model. Then numerical simulations were conducted, in parallel with the co-culture experiments. The simulated results were repeatedly compared with the experimental data.

With these gene mutations, a tan sets off melanoma

The researchers plan to continue to expand their model in combination with data from real-world experiments in cancer cell growth. This combination of theoretical modeling with laboratory experiments could lead to additional insights into the factors that contribute to cancer cell growth.

“Tumors grow in places where normal, healthy cells can’t because the cells are already densely packed,” says Suhov.

“Contact inhibition, which we modeled as exclusion area, may be one of the things that prevents non-cancer cells from spreading uncontrollably, but cancer cells somehow overcome this,” Suhov explains. “On the other hand, the normal cells try to form ‘border layers’, of a higher cell density, surrounding tumor-like clusters as if they wanted to isolate tumors and prevent them from spreading further. Our model shows that these factors are relevant when one tries to explain the images of cell growth seen in the laboratory.

“It is quite remarkable that the mixture of cells from unrelated biological sources shows a persistent pattern of behavior. However, we would like to expand this to gain a better understanding of how cancer cells behave within a natural setting. As we continue to refine our model based on additional experimental data, we may be able to build in parameters that allow us to better understand the precise biological processes that cause tumors to form,” Suhov says.

Broccoli-based compound may treat melanoma

The researchers report their findings in the journal Scientific Reports.

Funding for the research came from the Coordenao de Aperfeioamento de Pessoal de Nível Superior (CAPES) in Brazil, the University of Denver mathematics department, the Programa de Educação – MEC/SESu in Brazil, and the Penn State mathematics department.

Source: Penn State

The post Math model simulates growing melanoma appeared first on Futurity.

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