19 July 2006
Listeriosis' path to miscarriage traced to placental infection
For years, doctors have puzzled over why pregnant women are 20 times more likely than others to be infected by the bacterium Listeria monocytogenes. In a study posted in the June issue of the online journal PLoS Pathogens (pathogens.plosjournals.org), Berkeley researchers have shown that the bacteria can invade the placenta, where - protected from the body's immune system - they proliferate rapidly before pouring out to infect organs such as the liver and spleen. The illness they cause often results in miscarriage or infection of the fetus.
The study is the first to trace such a pathway of infection, and it dashes the widely held assumption that immune-system changes during pregnancy are to blame for elevated Listeria infection rates.
"The reason the mother is more susceptible is not necessarily because her immune system is compromised, but because the bacteria that got into her placenta are infecting her," said Anna Bakardjiev, the study's lead author and a postdoctoral researcher with Daniel Portnoy, professor of biochemistry and molecular biology. "The miscarriages that result from these infections may be a natural defense mechanism to dispel this source of infection."
Portnoy and Bakardjiev are now studying how Listeria moves from the digestive tract to the placenta. "An understanding of these mechanisms," Portnoy said, "might contribute to designing methods for prevention and therapy of listeriosis in pregnant women."
- Liese Greensfelder
Effectiveness of No Child act tough to gauge, study finds
Many states provide erratic, exaggerated reports of student achievement trends that make it impossible to determine the effectiveness of the federal No Child Left Behind Act, according to a study released this month led by Berkeley researchers.
The 14-month study by Policy Analysis for California Education (PACE), an independent research center based at Berkeley, UC Davis, and Stanford University, compared state and federal test- score trends for math and reading proficiency across 12 states between 1992 and 2005.
The No Child act required for the first time that all states participate in a federal testing program, enabling analysts to compare any state's claims of progress in test results against the uniform federal standard. Since the act's passage, analysts have worried that states would "dumb down" their tests, making it easier for all students to become proficient by 2013 as mandated by the act.
The PACE researchers found that governors and state school chiefs often do just that. This makes it "almost impossible for parents and local educators to determine whether children's achievement is going up or down," said Fuller.
Researchers also found that many states have continued to report achievement gains that far exceed the rate of progress estimated by federal officials. For example, California has reported a 3.7 percent average annual increase since 2002 in the share of fourth graders proficient in reading, compared with flat test-score performance as gauged by federal standards.
Overall, the study reports that federal reading scores have remained flat in the 12 states examined after No Child Left Behind kicked in, reflecting a nationwide trend. Math scores have inched upward on the national assessment, while states continue to report much higher rates of improvement.
Various steps can be taken to bring more credibility to state testing programs, said the researchers. Those include benchmarking state tests to federal standards, improving tests to better reflect analytical and writing skills as well as higher-ordered thinking, and providing federal support to states to ensure that trends over time can be reported reliably when testing programs change.
The report is online at pace.berkeley.edu/testscoretrends.html.
- Kathleen Maclay