Research Profile

George McCabe - Bone Resorption in Postmenopausal Women

George_Jackson_Connie_Weaver_George_McCabe-AMS Pictured left to right: Associate Research Scientist George
Jackson, Professor Connie M. Weaver, and Professor George
McCabe in the PRIME Lab at Purdue University standing in
front of the accelerator.
Osteoporosis is a disease that reduces bone mineral density (BMD), which in turn increases the risk of fracture, often in the hip, spine, or wrist [1]. Although osteoporosis can occur in both men and women, it is observed most frequently in postmenopausal women. Such women experience a steady state of decline in bone resorption over time as the ovaries stop producing estrogen. Many alternatives exist to help in the treatment of osteoporosis, but it is of great interest to determine strategies that can prevent osteoporosis from occurring. These strategies can involve pharmaceuticals, dietary supplements, and changes in lifestyle, through exercise and nutrition. Professor George McCabe, with Dr. Connie M. Weaver, Distinguished Professor and Head of the Purdue University Department of Foods and Nutrition, have been working with the support of the Purdue University / University of Alabama Birmingham NIH Botanical Research Center for Age Related Diseases to determine whether botanical treatments can be effective preventative measures against osteoporosis for postmenopausal women.

Professor McCabe, his former graduate student Joe Nolan, and colleagues in the Department of Foods and Nutrition specifically looked at the dose response effect of genistein (an isoflavone found in a number of plants, such as soybeans) and the interaction with other soy isoflavones on calcium absorption and bone resorption in postmenopausal women who produce equol (a non-steroidal estrogen) and those who do not [2]. All subjects were dosed with Calcium-41 (Ca-41), which is used as a biological tracer for bone resorption; this compound is absorbed by the bone and can be separated from other isotopes of calcium. The botanical treatments were assigned to each subject using a crossover design to determine whether the treatments have an effect on the rate of decrease Ca-41 resorption in the bones. After a burn-in period, the researchers were able to detect the levels of Ca-41 present in urine samples from each subject during each treatment using Accelerator Mass Spectrometry (AMS). Results were expressed using the relative resorption, which is calculated as the ratio of the level of urinary Ca-41 in a treatment period divided by the level in a baseline period. In this study, Professor McCabe intends to establish a methodology that could be used to explore other treatments for osteoporosis, regardless of the source. He also hopes to help address the challenge of reporting scientific results to a broader community and the growing need for enhanced communication between statisticians and their audience; this project highlights the importance of presenting statistical results in a clear and understandable way, not only to collaborating scientists in other fields, but also to the general public.

Professor McCabe joined the Department of Statistics in 1970, and is currently the Associate Dean for Academic Affairs in the College of Science. In addition to nutrition, his many research interests include bioinformatics and biologically related disciplines, computer methods for statistical inference, experimental design, modeling and model selection, and statistics education. For more information on Professor McCabe, please visit his homepage.

[1] Wikipedia, Osteoporosis
[2] Purdue Botanical Research Center for Age Related Diseases

December 2007