Adult Weight Gain Tied to Prostate Cancer Risk

Tuesday, September 1, 2009

TUESDAY, Sept. 1 (HealthDay News) -- Men who pack on excess pounds as young adults are at heightened risk of developing prostate cancer, although the risk varies by ethnic group, researchers from the University of Hawaii report.

Obesity is a risk factor for many common cancers, including colorectal cancer and breast cancer in postmenopausal women. However, whether obesity plays a role in prostate cancer risk has been unclear, researchers say.

The new study finds that "body mass in both younger and older adulthood, and weight gain between these periods of life, may influence prostate cancer risk," said study author Brenda Y. Hernandez, an assistant professor at the Cancer Research Center of Hawaii.

The report is published in the September online issue of Cancer Epidemiology, Biomarkers & Prevention.

For the study, Hernandez's team looked at the relationship between weight and prostate cancer in a multiethnic population including blacks, Japanese, Hispanics, Native Hawaiians and whites, all of whom who participated in a long-term study called the Multiethnic Cohort.

The researchers collected data on almost 84,000 men who participated in the study. In all, more than 5,500 men were diagnosed with prostate cancer. Men who were overweight or obese at 21 had a lower risk of localized and low-grade prostate cancer, the researchers found.

When men put on weight seemed to matter, as did race and ethnicity. For example, "higher weight in older adulthood was associated with increased risk of prostate cancer among white and Native Hawaiian men and a decreased risk of prostate cancer among Japanese men," Hernandez said.

And excessive weight gain in young adulthood increased the risk of advanced and high-grade prostate cancers (the more dangerous kind) for white men, the report found. For black men, excessive weight gain as a young adult upped risks for less hazardous, localized and low-grade forms of the disease.

Genes and lifestyle may account for these differences in risk, Hernandez speculated. "The relationship of certain characteristics, such as body size, with cancer risk may vary across ethnic groups due to the combined influence of both genes and lifestyle," she said. "This study underscores the importance of investigating cancer etiology in diverse populations."

Victoria Stevens, strategic director of laboratory services at the American Cancer Society, said the study shows there are differences in ethnic groups, but these differences are not straightfoward.

"Their findings aren't definitive," Stevens said. "They are just not clear-cut, you don't see a simple linear relationship."

"The paper is very suggestive, but it is not clear in prostate cancer whether weight gain is as important" as it is for other malignancies, she said. "Exactly what that risk is, we still don't know."

SOURCES: Brenda Y. Hernandez, Ph.D., M.P.H., assistant professor, Cancer Research Center of Hawaii, University of Hawaii, Honolulu; Victoria Stevens, Ph.D., strategic director, laboratory services, American Cancer Society; September 2009 Cancer Epidemiology, Biomarkers & Prevention, online

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The Path to New Antibiotics

LA JOLLA, Calif., August 27, 2009 -- Researchers at Burnham Institute for Medical Research (Burnham), University of Texas Southwestern Medical Center and University of Maryland have demonstrated that an enzyme that is essential to many bacteria can be targeted to kill dangerous pathogens. In addition, investigators discovered chemical compounds that can inhibit this enzyme and suppress the growth of pathogenic bacteria. These findings are essential to develop new broad-spectrum antibacterial agents to overcome multidrug resistance. The research was published in the Cell journal Andrei Osterman, Ph.D., an associate professor in Burnham’s Bioinformatics and Systems Biology program, and colleagues, targeted the bacterial nicotinate mononucleotide adenylyltransferase (NadD), an essential enzyme for nicotinamide adenine dinculeotide (NAD) biosynthesis. NAD has many crucial functions in nearly all important pathogens and the bacterial NadD differs significantly from the human enzyme.

“It’s clear that because of bacterial resistance, we need new, wide-spectrum antibiotics,” said Dr. Osterman. “This enzyme is indispensable in many pathogens, so finding ways to inhibit it could give us new options against infection.”

According to the National Institutes of Health, drug resistance is making many diseases increasingly difficult—and sometimes impossible—to treat. They point to tuberculosis and methicillin-resistant Staphylococcus aureus (MRSA) as two pathogens that pose a serious threat to human health.

Using a structure-based approach, the team searched for low-molecular-weight compounds that would selectively inhibit bacterial NadD, but not the human equivalent, by screening, in silico, more than a million compounds. Experimental testing of the best predicted compounds against Escherichia coli and Bacillus anthracis (anthrax) led them to a handful of versatile inhibitory chemotypes, which they explored in detail. Using protein crystallography, a 3D structure of the enzyme in complex with one of the inhibitors was solved providing guidelines for further drug improvement.

“This is proof-of-concept that NadD is a good target to create antibacterial agents,” said Dr Osterman. “This knowledge will be useful for both biodefense and public health. The next step is to find better inhibitors. We do not have a silver bullet yet, but we are certainly hitting a golden target.”

This research was supported by a grant from the National Institute of Allergy and Infectious Diseases.

About Burnham Institute for Medical Research
Burnham Institute for Medical Research is dedicated to discovering the fundamental molecular causes of disease and devising the innovative therapies of tomorrow. Burnham, with operations in California and Florida, is one of the fastest-growing research institutes in the country. The institute ranks among the top four institutions nationally for NIH grant funding and among the top 25 organizations worldwide for its research impact. For the past decade (1999-2009), Burnham ranked first worldwide in the fields of biology and biochemistry for the impact of its research publications (defined by citations per publication), according to the Institute for Scientific Information.

Burnham utilizes a unique, collaborative approach to medical research and has established major research programs in cancer, neurodegeneration, diabetes, and infectious, inflammatory, and childhood diseases. The Institute is especially known for its world-class capabilities in stem cell research and drug discovery technologies. Burnham is a nonprofit public benefit corporation.

People who drink alcohol are likely to exercise more than teetotalers

Drinkers aren't just bending their elbows: according to a new study, the more alcohol people drink, the more likely they might be to exercise.

"Alcohol users not only exercised more than abstainers, but the differential actually increased with more drinking," said lead author Michael French, Ph.D. "There is a strong association between all levels of drinking and both moderate and vigorous physical activity. However, these results do not suggest that people should use alcohol to boost their exercise programs, as the study was not designed to determine whether alcohol intake actually caused an increase in exercise."

French is a professor of health economics at the University of Miami. The study appears in the September/October issue of the American Journal of Health Promotion.

French and colleagues analyzed data from the 2005 Behavioral Risk Factor Surveillance System, a yearly telephone survey of roughly 230,000 Americans. They uncovered a strong statistical association between measures of both alcohol use and moderate to vigorous exercise.

Among women, those currently using alcohol exercised 7.2 minutes more per week than those who abstained. Relative to abstainers, the more alcohol used, the longer the person exercised. Specifically, light, moderate and heavy drinkers exercised 5.7, 10.1 and 19.9 minutes more per week. Overall, drinking was associated with a 10.1 percent increase in the probability of engaging in vigorous physical activity. The results for men were similar.

French said that the health problems associated with heavy drinking may outweigh the benefits of more exercise. "While those who are at risk for problem drinking should minimize or curtail their consumption of alcohol, light to moderate drinking may be health-enhancing for some people. If responsible drinkers are using exercise to partially counteract the caloric intake from alcohol, that is not such as bad thing."

To Bethany Garrity, director of corporate fitness management at the National Institute for Fitness and Sport in Indianapolis, these results challenge the status quo assumption that healthy people make all the right choices.

"We don't often associate an unhealthy behavior such as moderate to heavy drinking with healthy behaviors in the same individual," she said. "Sometimes people tend to forget that we are not all healthy or all unhealthy in how we behave. This is a good reminder that people choose many kinds of health behaviors across the spectrum from healthiest to unhealthy."