February 2007

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Research

David Ludwig, MD, PhD

Nutrition studies too often follow the money
Studies funded by the beverage industry tend to reach conclusions in synch with industry interests. That's the finding of an analysis by Children's Hospital Boston researcher David Ludwig, MD, PhD, published online in the January 9 issue of PLoS Medicine.

Ludwig and colleagues began with a Medline search of scientific articles about soft drinks, juice and milk published from 1999 to 2003. They found 111 articles that looked at human health effects and declared financial sponsorship. To guard against bias themselves, they carved up the work: One investigator, with no knowledge of those studies' conclusions, ascertained the funding source; others, knowing nothing of the funding, classified the articles' conclusions as "favorable," "neutral" or "unfavorable."

As was widely reported by the media, the researchers found was that studies funded solely by industry were four to eight times more likely than non-industry-funded studies to reach conclusions that were favorable to the sponsors' financial interests. Findings were especially striking for intervention studies, such as those that directly gave people beverages and examined the effects: No studies funded solely by industry had unfavorable conclusions, compared with 37 percent of independent studies.

The bias may take several forms, including framing research questions in slanted ways or simply not publishing unfavorable results, says Ludwig, who directs Children's Optimal Weight for Life program. The implications are serious, he believes, since nutrition studies influence dietary guidelines, nutrition intervention programs, and government regulation of food and beverage health claims. "If the science is compromised by conflict of interest, that's a top-order threat to public health," he says.

George Daley, MD, PhD

Customized embryonic stem cells from eggs alone
Patients might someday be able to be treated with embryonic stem cells created from female eggs alone, suggests a new study. The cells, capable of creating any tissue in the body, would be genetically matched to their immune system, so could be transplanted without risk of rejection, say Children's Hospital Boston researchers George Daley, MD, PhD, associate director of Children's Stem Cell Program, and Kitai Kim, PhD, a research fellow in Hematology/Oncology.

This idea, reported online in the journal Science on December 12, is based on research in mice. If proven to work in humans, it would eliminate tissue matching and tissue rejection problems that often prevent successful transplantation, says Daley.

The work is based on a method of reproduction called parthenogenesis, in which females generate offspring without the contribution of a male. Though parthenogenesis doesn't normally happen in mice, Daley, Kim and colleagues chemically induced unfertilized mouse eggs to develop into embryos. They then collected embryonic stem cells, singling out those whose major histocompatibility complex genes (responsible for tissue matching) were identical to those of the mice. Injected back into the mice, stem cells formed a variety of tissues and weren't rejected by the immune system. Daley's laboratory is now trying to accomplish the same feats with human eggs.

Embryonic stem cells can also be created through somatic cell nuclear transfer, in which an egg's nucleus is removed and replaced with the nucleus of a donor cell. This method, which Daley's lab is working to perfect, creates a completely genetically matched embryonic stem cell, but is cumbersome and inefficient. "Generating embryonic stem cells from unfertilized eggs may allow us to move toward human applications sooner," Daley says.

He cautions, however, that tissues derived from parthenogenetic stem cells might have subtle abnormalities. "We'll have to demonstrate the safety and durability of these cells before we imagine any clinical use," he says.

:: Erin Graham, Editor :: Masthead ::

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