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Week of July 8, 2013

Scholarship & Creative Work

Has motorization in the US reached its peak?

Fewer light vehicles are on America’s roads today than five years ago, thanks possibly to increases in telecommuting and public transportation, a U-M researcher says.

 

Michael Sivak, a research professor at the U-M Transportation Research Institute, studied recent trends in the numbers of registered cars, pickup trucks, SUVs and vans in the U.S. from 1984 to 2011. He examined both the absolute numbers and rates per person, per licensed driver and per household.

Sivak found that the absolute number of registered vehicles reached a maximum of 236.4 million in 2008, 2.6 million more than in 2011.

“It is likely that this was only a temporary maximum and that the decline after 2008 was primarily driven by the current economic downturn that started that year,” Sivak said. “Consequently, with the improving economy and the expected increase in the U.S. population, it is highly likely that from a long-term perspective, the absolute number of vehicles has not yet peaked.”

He found, however, that rates of vehicles per person, per licensed driver and per household reached their highest levels most recently in 2006—two years before the economy stalled. The rates that year were 0.79 vehicles per person, 1.16 per licensed driver and 2.05 per household. In 2011, the rates were 0.75, 1.10 and 1.95, respectively.

“It is likely that the declines in these rates prior to the current economic downturn reflect other societal changes that influence the need for vehicles—such as increases in telecommuting and in the use of public transportation,” Sivak said.

Sivak said that changes in the rates from 2008 on, however, likely reflect both the economy and a variety of societal changes.

“Whether the recent maxima in the rates will represent long-term peaks, as well, will be influenced by the extent to which the relevant societal changes turn out to be permanent,” he said.

Zebrafish help identify mutant gene in rare muscle disease

Zebrafish with very weak muscles helped scientists decode the elusive genetic mutation responsible for Native American myopathy, a rare, hereditary muscle disease that afflicts Native Americans in North Carolina.

Scientists led by John Kuwada, professor of molecular, cellular and developmental biology at U-M, and Hiromi Hirata of the National Institute of Genetics in Japan originally identified the gene in mutant zebrafish that exhibited severe muscle weakness. Native American myopathy causes muscle weakness from birth and other severe problems that can lead to death before adulthood.

The findings appear in the journal Nature Communications.

The responsible gene encodes for a muscle protein called Stac3, which in turn regulates a physiological process required for muscle contraction. The muscles of zebrafish and people with the genetic mutation don’t make normal Stac3 protein and the muscles don’t contract effectively.

Scientists established the importance of Stac3 for muscle function in zebrafish by studying the small fish physiologically and genetically. Scientists then looked at the human version of the gene, and found that the gene was mutated in people suffering from Native American myopathy.

For many degenerative muscle diseases few drugs help, largely because scientists don’t know the genes responsible for many of these muscle diseases, making it difficult to develop drugs and other therapies that target the condition. The discovery of the gene for Native American myopathy, however, may help develop drugs to treat the myopathy, as well as other related muscle diseases.

This research was supported by grants from NINDS, NSF, NIAMS, Taubman Medical Institute, and the Muscular Dystrophy Association.

Nuke test radiation can fight poachers

A U-M researcher worked with University of Utah colleagues to develop a new weapon to fight poachers who kill elephants, hippos, rhinos and other wildlife.

By measuring radioactive carbon-14 deposited in tusks and teeth following open-air nuclear bomb tests, the method reveals the year an animal died, and thus whether the ivory was taken illegally.

“This could be used in specific cases of ivory seizures to determine when the ivory was obtained and thus whether it is legal,” said University of Utah geochemist Thure Cerling, senior author of the study.

U-M paleontologist Daniel Fisher worked with Cerling and a former University of Utah researcher, Kevin Uno, on the project. A report about the new method is scheduled for online publication July 1 in the Proceedings of the National Academy of Sciences.

Fisher studies mammoths and mastodons, and over several decades has developed techniques to interpret the life histories of those prehistoric pachyderms by analyzing growth layers within their tusks. He shared those techniques with Cerling and Uno, who then applied them to modern-day elephant tusks and teeth.

“Not only can this method help wildlife forensics to combat poaching, but it’s also provided conclusive validation of earlier work that had suggested that tusks and many teeth are made of layers that reflect consecutive years in the life of the animal that grew them,” said Fisher, co-author of the paper and a U-M professor of paleontology and of Earth and environmental sciences.

“Whether we’re dealing with animals from today’s ecosystems or fossils from the remote past, we can study these layers and extract information on climate, diet and conditions of g

Community-based lifestyle program improves diets of pregnant women

A healthy lifestyle intervention program tailored to Spanish-speaking pregnant Latinas significantly increased their daily consumption of vegetables and fiber.

The program also led to a decreased intake of added sugar, total and saturated fat, and the percentage of calories from solid fats and sugars compared to a control group, according to a new U-M study.

Researchers evaluated the effectiveness of Healthy Mothers on the Move (MOMs), a Detroit-based intervention program designed to reduce risk factors for type 2 diabetes in pregnant and postpartum Latinas.

The study demonstrates how pregnancy is an important time for interventions to improve dietary behavior that has consequences for the mother and the child, said Edith Kieffer, an associate professor of social work and study’s lead author.

Community health workers held two home visits and nine group meetings during pregnancy. The MOMs meetings offered a place for moms-to-be to get information about nutrition, discuss issues and learn how to exercise regularly and reduce stress. A key component of the MOMs intervention was informational and emotional support from the peers and community health workers who encouraged women to share strategies and to recognize each other’s efforts.

Added sugar and saturated fat consumption during pregnancy may increase the risk of gestational diabetes, weight retention after pregnancy and development of type 2 diabetes. The successful reduction of these dietary components by women participating in MOMs could help reduce their risk of developing diabetes.

The study’s other authors were Diana Welmerink, Brandy Sinco, Kathleen Welch, Erin Rees Clayton and Virginia Uhley — all from U-M — and Christina Schumann of the Community Health and Social Services Center in Detroit.

The findings were published in the American Journal of Public Health.

Influenza infection increases likelihood of bacterial pneumonia 100-fold, study finds

It’s been known for more than two centuries that pneumonia cases increase during flu epidemics.

But population-level epidemiological studies looking at seasonal patterns of influenza and pneumococcal pneumonia incidence have revealed either a modest association or have failed to identify any signature of interaction between the two.

These seemingly inconsistent observations at the personal and population scales have puzzled public health officials. Now a team of U-M researchers and their colleagues have used a novel approach that they say resolves the dichotomy and shows that influenza infection increases susceptibility to pneumococcus, the most common bacterial cause of pneumonia, by about 100-fold.

An accurate characterization of the influenza-pneumococcal interaction can lead to more effective clinical care and public health measures, including influenza pandemic preparedness, according to the authors.

“The results concerning the nature of the interaction between influenza and pneumococcal pneumonia were unequivocal in our study,” said U-M population ecologist and epidemiologist Pejman Rohani, senior author of a paper published in Science Translational Medicine. “Simply put, our analyses identified a short-lived but significant — about 100-fold — increase in the risk of pneumococcal pneumonia following influenza infection.”

The researchers also looked at the fraction of pneumonia cases that could be attributed to interaction with influenza. They found that during the peak of flu season, interaction with the influenza virus accounted for up to 40 percent of pneumococcal cases. But on an annualized basis, the fraction was between 2 percent and 10 percent of cases, a relatively subtle signature that could help explain why previous epidemiological analyses failed to detect the connection, Rohani and his colleagues concluded.

Rohani said the results suggest that the best way to reduce the incidence of bacterial pneumonia is to encourage the public to receive both pneumococcal and influenza vaccinations.

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FACULTY SPOTLIGHT

Stephen Stefanac, associate dean for patient services at the School of Dentistry, on what inspires him: "I am genuinely inspired by our students. They are extraordinary people — talented, motivated and eager to learn."

EVENTS

Noam Chomsky: “Language Use and Design: conflicts and their significance,” 7 p.m. July 11, Rackham Auditorium, part of the 2013 Linguistics Institute.

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