University of Minnesota produces study on molecular interactions to improve development of new medicines

A first-of-its-kind study on molecular interactions by biomedical engineers at the University of Minnesota’s College of Science and Engineering will make it easier and more efficient for scientists to develop new medicines and other therapies for diseases such as cancer, HIV and autoimmune diseases.

The study resulted in a mathematical framework that simulates the effects of the key parameters that control interactions between molecules that have multiple binding sites, as is the case for many medicines. Researchers plan to use the supercomputer model to develop a web-based app that other researchers can use to speed the development of new therapies for diseases. The research is published in an educational journal.

“The big advance with this study is that usually researchers use a trial-and-error experimental method in the lab for studying these kinds of molecular interactions, but here we developed a mathematical model where we know the parameters so we can make accurate predictions using a computer,” said Casim Sarkar, a University of Minnesota biomedical engineering associate professor and senior author of the study. “This computational model will make research much more efficient and could accelerate the creation of new therapies for many kinds of diseases.” This illustration highlights a small sampling of the 78 unique binding configurations that arise when molecule chains with three binding sites interact. The research team developed a computational model that can predict how key parameters can be “dialed up” or “dialed down” to control how such molecules with more than one binding site interact with one another. This should accelerate biological research and discovery of new medicines. Image credit: Errington et al., University of Minnesota {module INSIDE STORY}

The research team studied three main parameters of molecular interactions—binding strength of each site, the rigidity of the linkages between the sites, and the size of the linkage arrays. They looked at how these three parameters can be “dialed up” or “dialed down” to control how molecule chains with two or three binding sites interact with one another. The team then confirmed their model predictions in lab experiments.

“At a fundamental level, many diseases can be traced to a molecule not binding correctly,” said Wesley Errington, a University of Minnesota biomedical engineering postdoctoral researcher and lead author of the study. “By understanding how we can manipulate these ‘dials’ that control molecular behavior, we have developed a new programming language that can be used to predict how molecules will bind.”

The need for a mathematical framework to decode this programming language is highlighted by the researchers’ finding that, even when the interacting molecule chains have just three binding sites each, there are a total of 78 unique binding configurations, most of which cannot be experimentally observed. By dialing the parameters in this new mathematical model, researchers can quickly understand how these different binding configurations are affected, and tune them for a wide range of biological and medical applications.

“We think we’ve hit on rules that are fundamental to all molecules, such as proteins, DNA, and medicines, and can be scaled up for more complex interactions,” said Errington “It’s really a molecular signature that we can use to study and to engineer molecular systems. The sky is the limit with this approach.”

In addition to Sarkar and Errington, the research team included Bence Bruncsics from the Budapest University of Technology and Economics who was a visiting masters’ student in the Sarkar lab at the University of Minnesota. The team also partnered with the Institute for Therapeutics Discovery & Development (ITDD) at the University of Minnesota’s College of Pharmacy for the lab experiments to test the computational model. The research was funded by the National Institutes of Health.

Researchers at The University of Tokyo Institute of Industrial Science gaze into crystal balls to advance understanding of crystal formation

Crystallization is the physical phenomenon of the transformation of disordered molecules in a liquid or gas phase into a highly ordered solid crystal through two stages: nucleation and growth. Crystallization is very important in materials and natural sciences because it occurs in a wide range of materials, including metals, organic compounds, and biological molecules, so it is desirable to comprehensively understand this process. 

Colloids consisting of hard spheres suspended in a liquid are often used as a model system to study crystallization. For many years, a large discrepancy of up to ten orders of magnitude has been observed between the computationally simulated and experimentally measured nucleation rates of hard-sphere colloids. This discrepancy has typically been explained by the simulations not taking hydrodynamic interactions--the interactions between solvent molecules--into account. Researchers at The University of Tokyo Institute of Industrial Science, the University of Oxford, and the Sapienza University recently teamed up to further explore this explanation for the discrepancy between actual and calculated nucleation rates. {module INSIDE STORY}

The collaboration first developed a hard-sphere colloidal model that could reliably simulate the experimental thermodynamic behavior of real hard-sphere systems. Next, they conducted simulations of crystallization of the model system considering and neglecting hydrodynamic interactions to clarify the effect of these interactions on crystallization behavior.

"We initially designed a simulation model that accurately reproduced the real thermodynamics of hard-sphere systems," says study lead author Michio Tateno. "This confirmed the reliability and suitability of the model for use in further simulations."

The simulation results obtained using the developed model neglecting and considering hydrodynamic interactions revealed that hydrodynamic interactions did not affect nucleation rate, which was contrary to the prevailing consensus. Plots of nucleation rate against the proportion of hard spheres in the system were the same for calculations both with and without hydrodynamic interactions and also agreed with results reported by another research group.

"We performed calculations using the developed model with and without considering hydrodynamic interactions," explains senior author Hajime Tanaka. "The calculated rates of crystal nucleation were similar in both cases, which led us to conclude that hydrodynamic interactions do not explain the hugely different nucleation rates obtained experimentally and theoretically."

The research team's findings clearly illustrated that hydrodynamic interactions are not the origin of the large discrepancy between experimental and simulated nucleation rates. Their results further our understanding of crystallization behavior but leave the origin of this large discrepancy unexplained.

The article "Influence of hydrodynamic interactions on colloidal crystallization" was published in Physical Review Letters.

Waterloo develops AI to flag fake news for fact-checkers

A new artificial intelligence (AI) tool could help social media networks and news organizations weed out false stories.

The tool, developed by researchers at the University of Waterloo, uses deep-learning AI algorithms to determine if claims made in posts or stories are supported by other posts and stories on the same subject.

"If they are, great, it's probably a real story," said Alexander Wong, a professor of systems design engineering at Waterloo. "But if most of the other material isn't supportive, it's a strong indication you're dealing with fake news."

Researchers were motivated to develop the tool by the proliferation of online posts and news stories that are fabricated to deceive or mislead readers, typically for political or economic gain. {module INSIDE STORY}

Their system advances ongoing efforts to develop fully automated technology capable of detecting fake news by achieving 90 per cent accuracy in a key area of research known as stance detection.

Given a claim in one post or story and other posts and stories on the same subject that have been collected for comparison, the system can correctly determine if they support it or not nine out of 10 times.

That is a new benchmark for accuracy by researchers using a large dataset created for a 2017 scientific competition called the Fake News Challenge.

While scientists around the world continue to work towards a fully automated system, the Waterloo technology could be used as a screening tool by human fact-checkers at social media and news organizations.

"It augments their capabilities and flags information that doesn't look quite right for verification," said Wong, a founding member of the Waterloo Artificial Intelligence Institute. "It isn't designed to replace people, but to help them fact-check faster and more reliably."

AI algorithms at the heart of the system were shown tens of thousands of claims paired with stories that either supported or didn't support them. Over time, the system learned to determine support or non-support itself when shown new claim-story pairs.

"We need to empower journalists to uncover truth and keep us informed," said Chris Dulhanty, a graduate student who led the project. "This represents one effort in a larger body of work to mitigate the spread of disinformation."