The Latest in ...
RESEARCH ETHICS By Kristie Stoick, M.P.H., and John J. Pippin, M.D., F.A.C.C.
ALTERNATIVES TO ANIMAL RESEARCH
Engineered Human Cartilage Implant Successful
Since cartilage is one of the few tissues that does not regenerate after injury, scientists have been working on a way to implant cartilage from other sources—including animals. Now, however, tissue engineers at the University of Bristol in the United Kingdom have succeeded in growing a patient’s own cartilage in vitro on a protein scaffolding. Twenty-three patients with torn knee cartilage received the engineered cartilage tissue as an implant directly into their torn cartilage. After one year, the healthy engineered cartilage had knitted itself into the surrounding tissue, fixing the tears in almost half the patients. This technique could also offer hope to osteoarthritis sufferers, whose cartilage slowly degenerates.
Hollander AP, et al. Maturation of tissue engineered cartilage implanted in injured and osteoarthritic human knees. Tissue Eng. 2006;12(7):1787-1798.
Hepatitis Research Goes In Vitro
Scientists at Rockefeller University in New York have succeeded in developing a test-tube model for the hepatitis C virus (HCV) cultured in human cells. This model will permit research into how the virus infects human cells, as well as ways to prevent this infection and further spread of the disease.
Experiments on chimpanzees, monkeys, and mice have proven largely unhelpful in elucidating how hepatitis C causes disease or how to treat it. Aside from humans, only chimpanzees can naturally contract HCV, yet they do not develop the liver damage characteristic of humans with HCV.
Lindenbach BD, et al. Complete replication of hepatitis C virus in cell culture. Science. 2005;309:623-626.
Tetsuro Matsuzawa, a researcher who studies chimpanzees at Japan’s Kyoto University, is uncovering evidence that indicates that for specific tasks, chimpanzees are more intellectually developed than humans. Matsuzawa has found that chimpanzees have better short-term memory skills than humans and can recognize the upside-down faces of other chimpanzees they know, while humans cannot do the same with familiar human faces. Finally, Matsuzawa has found that chimpanzees in the wild have a “botanist’s memory” for as many as 200 plants in their surrounding habitat, keeping track of what each plant is used for, where it is located, and when it is in season.
New Scientist 2006;2555:48.
“A Critical Look at Animal Experimentation”
The latest edition of this well-researched and extensively referenced 34-page brochure is authored by six physicians and scientists with knowledge and personal experience in medicine, animal and human research, and drug testing. It is published by the Medical Research Modernization Committee and is offered free of charge. It critically examines the limitations of animal “models” of human diseases and the human health risks that result from unreliable animal research.
Illustrative examples of the authors’ critiques are provided, including the failures of more than 80 HIV/AIDS vaccines, more than 150 stroke treatments, and more than 90 percent of drugs that looked safe in animals. This valuable brochure is also available in French and German.
NUTRITION By Dulcie Ward, R.D., and Susan Levin, M.S., R.D.
Pima Study Points Finger at Diet—Not Genes—in Diabetes Risk
The Pima Indian population that resides in the Sierra Madre Mountains of Mexico is one-fifth as likely to have type 2 diabetes as the Pima Indian population living in the desert regions of Arizona, which has the world’s highest recorded prevalence and incidence of type 2 diabetes, despite a similar genetic background. Obesity was more than three times as frequent in the U.S. Pima women and 10 times more frequent in the U.S. Pima men than their Mexican counterparts. This large-scale health examination, which analyzed the prevalence of diabetes, obesity, dietary intake, and physical activity in 743 non-Pima Mexicans, Mexican Pima, and U.S. Pima Indians, suggests that Westernized diet and lifestyle, rather than genetic tendencies, are responsible for the global type 2 diabetes epidemic. American Indians living on reservations are more likely to have a diet composed of high-fat U.S. Department of Agriculture commodity foods, whereas Mexican Pimas’ simple diet is based on high-fiber beans, wheat and corn tortillas, and potatoes. Mexican Pima Indians had much greater physical activity levels than their U.S. counterparts as well.
Schulz LO, Bennett PH, Ravussin E, et al. Effects of traditional and western environments on prevalence of type 2 diabetes in Pima Indians in Mexico and the U.S. Diabetes Care. 2006;29:1866-1871.
Vegetarians: Better Insulin Sensitivity, Less Diabetes Risk
A recent study compared the health of 49 Taiwanese vegetarian women with that of age-matched omnivores. The vegetarians had significantly greater insulin sensitivity, putting them at lower risk of developing type 2 diabetes and cardiovascular disease. Diets high in fat and saturated fat decrease insulin sensitivity, putting the omnivores at greater risk.
Hung C, Huang P, Li Y, Lu S, Ho L, Chou H. Taiwanese vegetarians have higher insulin sensitivity than omnivores. Br J Nutr. 2006;95:129-135.
Dramatic Rise in Overweight and Obesity in China
A recent review of China’s 2002 national nutrition and health survey showed a dramatic increase in the prevalence of overweight and obesity. In a society where people have traditionally been slim, China now has 184 million overweight and 31 million obese citizens. The prevalence of overweight and obesity is 14.7 percent and 2.6 percent, respectively. That’s still low compared with Western countries, such as the United States, where more than 60 percent of the population is overweight or obese. However, in Chinese boys aged 7 to 18, the prevalence of overweight and obesity has increased by 28 times since the last census in 1985. Causes for the sudden epidemic are not hard to find: The percentage of the diet coming from animal sources increased from 8 percent to 25 percent during that same 20-year span.
Wu Y. Overweight and obesity in China. BMJ. 2006;333:362-363.