Science And Tech Desert Herald Newspaper

Newly developed computer software combined with magnetic resonance imaging (MRI) of a fetus may help physicians better assess a womans potential for a difficult childbirth. Results of a study using the new software were presented November 29 at the annual meeting of the Radiological Society of North America (RSNA). Because a womans birth canal is curved and not much wider than a fetuss head, a baby must move through the canal in a specific sequence of maneuvers. A failure in the process, such as a head turned the wrong way at the wrong time, can result in dystocia, or difficult labor.

Using the new software, called PREDIBIRTH, Dr. Ami and a team of researchers processed MR images of 24 pregnant women. The result was a three-dimensional (3-D) reconstruction of both the pelvis and the fetus along with 72 possible trajectories of the babys head through the birth canal.

Based on these simulations, the program scored each mothers likelihood of a normal birth.

For purposes of the study, the PREDIBIRTH scores were computed retrospectively and measured against delivery outcomes for the 24 women. Thirteen women delivered normally. These deliveries were scored as highly favorable by the simulator. Three women who delivered by elective cesarean-section (C-section) — two of which involved babies of excessive weight — were scored at high risk for dystocia.

This is the first time that anyone has studied how the wires in an electronic circuit interact with one another when packed so tightly together. Surprisingly, the authors found that the effect of one wire on the other can be either positive or negative. This means that a current in one wire can produce a current in the other one that is either in the same or the opposite direction. This discovery, based on the principles of quantum physics, suggests a need to revise our understanding of how even the simplest electronic circuits behave at the nanoscale.

“We simulated what happens in this enzyme over a time scale of 0.3 microseconds, which sounds very fast, but from a scientific point of view, it’s a relatively long time,” Baudry said. “A lot of things happen at this scale that had never been seen before. It’s a computational tour de force to be able to follow that many water molecules for that long.”

The team’s study of the water molecules’ movements contributes to a broader understanding of drug processing by P450 enzymes. Because some populations have a slightly different version of the enzymes, scientists hypothesize that mutations could partially explain why people respond differently to the same drug. One possibility is that the mutations might shut down the channels that bring water molecules in and out of the enzyme’s active site, where the chemical modification of drugs takes place. This could be investigated by using the computational tools developed for this research.

By simulating how water molecules move in and out of the protein’s centrally located active site, the team clarified an apparent contradiction between experimental evidence and theory that had previously puzzled researchers. X-ray crystallography, which provides a static snapshot of the protein, had shown only six water molecules present in the active site, whereas experimental observations indicated a higher number of water molecules would be present in the enzyme.

“We found that even though there can be many water molecules — up to 12 at a given time that get in and out very quickly — if you look at the average, those water molecules prefer to be at a certain location that corresponds to what you see in the crystal structure,” Miao said. “It’s a very dynamic hydration process that we are exploring with a combination of neutron scattering experiments and simulation.”

“This new switch is superior to existing single-molecule concepts,” said Hrvoje Petek, principal investigator and professor of physics and chemistry in the Kenneth P. Dietrich School of Arts and Sciences and codirector of the Petersen Institute for NanoScience and Engineering (PINSE) at Pitt. “We are learning how to reduce electronic circuit elements to single molecules for a new generation of enhanced and more sustainable technologies.”

The switch was discovered by experimenting with the rotation of a triangular cluster of three metal atoms held together by a nitrogen atom, which is enclosed entirely within a cage made up entirely of carbon atoms. Petek and his team found that the metal clusters encapsulated within a hollow carbon cage could rotate between several structures under the stimulation of electrons. This rotation changes the molecule’s ability to conduct an electric current, thereby switching among multiple logic states without changing the spherical shape of the carbon cage. Petek says this concept also protects the molecule so it can function without influence from outside chemicals.

The research was led by Petek in collaboration with chemists at the Leibnitz Institute for Solid State Research in Dresden, Germany, and theoreticians at the University of Science and Technology of China in Hefei, People’s Republic of China. The experiments were performed by postdoctoral researcher Tian Huang and research assistant professor Min Feng, both in Pitt’s Department of Physics and Astronomy.