Diseases such as mad cow disease (bovine spongiform encephalopathy or BSE), which are caused by faulty proteins called prions, could be treated by adding closely related, noninfectious prions from other species. This sort of therapy could increase the incubation period of the disease well past a human lifetime, according to a theoretical study by physicists at the University of California, Davis.
Prion diseases like BSE are caused when a common protein in the brain, PrP, does not fold properly. Somehow, this faulty protein makes other PrP proteins fold in the same way. The misfolded proteins build up and stick together, forming mats and tangles in the brain.
Graduate student Alex Slepoy and colleagues built a mathematical model of prion growth. They set rules for how a few infectious prions convert normal PrP proteins around them. As more proteins are altered and can affect their neighbors, the damage spreads at an increasing rate.
The change in protein folding takes less than a billionth of a second, but the disease that results can take decades to develop, said Daniel Cox, who with fellow UC Davis physicist Rajiv Singh is one of the senior authors on the study. The model was intended to bridge the gap between these time scales, Cox said. Predictions from the model were a good fit with data from the BSE epidemic in cattle in England, he said.
Prions can jump from one species to another. Some cases of human disease in England were likely caused by meat contaminated with BSE prions. But in some cases, the prions are incompatible. For example, mouse prions can attack hamsters, but hamster prions do not thrive in mice.
The UC Davis team used their model to see what would happen if incompatible, foreign prions in their correctly folded form were added to a prion infection in progress. They found that if the dose were high enough, the foreign prions would block infectious prions from converting normal proteins and forming aggregates. This would slow down or stop the spread of the disease.
Although this treatment is only a theoretical possibility at the moment, this sort of therapy could increase the disease incubation time well past a human lifetime. Cox and Singh are now hoping to use a similar model to study Alzheimer's disease, based on data collected by the UC Davis Medical Center.
The study is published in a recent issue of Physical Review Letters.
Media contacts: Daniel Cox, Physics, 530-752-1789, cox@physics.ucdavis.edu; Rajiv Singh, Physics, 530-752-4710, singh@physics.ucdavis.edu; Andy Fell, News Service, 530-752-4533, ahfell@ucdavis.edu.
COLD PLANET STOPPED AGRICULTURE FROM DEVELOPING
Although many worry how global warming will affect the planet, University of California researchers theorizing why it took so long for agriculture to develop say that global cooling is a bigger problem for human survival.
Agriculture was impossible 13,000 years ago during the Ice Age, although humans were otherwise quite sophisticated, say UC Davis Professors Peter Richerson and Robert Bettinger and UCLA Professor Robert Boyd. They are authors of an article on the subject published in the July issue of American Antiquity, an archeology journal.
Paleoclimatologists studying ice cap and ocean cores have recently discovered that during the Ice Age, the climate changes were erratic, with temperatures swinging sometimes from warm to glacial within a decade.
"We argue that climate had been making things worse off and on over the whole of human existence," Bettinger says. "Agriculture developed when the climate became dramatically nicer."
The researchers hypothesize that "the reduction in climate variability, increase in carbon dioxide in the atmosphere and increases in rainfall rather abruptly changed the Earth from a regime where agriculture was impossible everywhere to one where it was possible in many places."
But developing agriculture took more than those climatic changes. Humans needed to create functional systems integrating social institutions and agricultural technology. "People can't change that quickly. Full-scale agriculture took thousands of years to develop, and social and agricultural innovation is ongoing today," Richerson says.
However, once agriculture took hold, groups that efficiently used plant resources were able to increase their populations dramatically.
Media contacts: Robert Bettinger, UC Davis Anthropology, 530-752-6343, rlbettinger@ucdavis.edu; Peter Richerson, UC Davis Environmental Science and Policy, 530-752-2781, pjricherson@ucdavis.edu; Susanne Rockwell, UC Davis News Service, 530-752-9841, sgrockwell@ucdavis.edu; Andy Fell, UC Davis News Service, 530-752-4533, ahfell@ucdavis.edu.
FEELINGS OF SECURITY ANTIDOTE TO HOSTILITY, FEAR
Human hostility toward outsiders can be reduced if people feel loved and secure, say UC Davis and Israeli psychologists who have been researching Israeli Jewish student attitudes toward other groups.
The psychologists believe they have located the part of the mind where feelings of security and love can affect positive attitudes toward outsiders.
Phillip Shaver, a psychology professor at UC Davis, and Mario Mikulincer, a psychology professor at Bar-Ilan University in Israel, published their findings in a recent issue of the Journal of Personality and Social Psychology. "A normal aspect of human conflict is fear and hostility," Shaver says. "You can reduce someone's sense of threat at a deep unconscious level by activating associations to love and security."
Borrowing from a theory about infants' attachment behavior with their mother, the researchers showed that Jewish students felt more benevolent toward Arabs and Russian immigrants after feelings of security were triggered subconsciously.
The subjects were presented subliminal words such as "love" and "support" within a computerized word-relation test. They then were asked to evaluate people within their own religious group, ethnic background and gender as well as "outsiders" who were Arabs or Russian immigrants.
Shaver and Mikulincer will continue their research using a $100,000 grant from the Fetzer Institute of Michigan for research that sheds light on altruistic love.
"We want to see if people who volunteer to help others are more secure or, if by volunteering, it makes them become more secure," Shaver says.
Media contacts: Phillip Shaver, UC Davis Psychology, 530-754-8304, prshaver@ucdavis.edu; Mario Mikulincer, Bar-Ilan University, visiting Shaver Aug. 21-Sept. 10, can be reached through Shaver's number, mikulm@mail.biu.ac.il; Susanne Rockwell, UC Davis News Service, 530-752-9841, sgrockwell@ucdavis.edu.