MedicalResearch.com Interview with:
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Dr. Xifeng Wu[/caption]
Dr. Xifeng Wu, MD PhD
Department Chair, Department of Epidemiology, Division of OVP, Cancer Prevention and Population Sciences
Director, Center for Translational and Public Health Genomics
Professor, Department of Epidemiology
Division of Cancer Prevention and Population Sciences
The University of Texas MD Anderson Cancer Center, Houston, Texas
Medical Research: What is the background for this study? What are the main findings?
Dr. Wu: Obesity is a well-established risk factor for renal cell carcinoma (RCC), the most common form of kidney cancer. It has been estimated that more than 40% of RCC incident cases in the US may be attributed to excessive body weight. Growing body of evidence suggests that obesity may also influence clinical outcome of RCC; however, the findings are sometimes conflicting. So far, the molecular mechanism linking obesity to RCC risk or prognosis is not well understood. In this study, we evaluated the promoter CpG site methylation of 20 candidate obesity-related genes and their association with RCC risk and recurrence in a two-phase study of 240 newly diagnosed, previously untreated RCC patients. Pyrosequencing was conducted on paired RCC tumor and normal adjacent tissues to measure promoter methylation. Among the 20 markers, we found
NPY,
LEP and
LEPR showed significant differential methylation levels between tumors and normal adjacent tissues, and methylation was significantly higher in tumors in both discovery and validation groups. Consistent with our findings, we also found lower expression of
LEPR in tumor tissues compared to normal adjacent tissues in data obtained from The Cancer Genome Atlas. Additionally, high
LEPR methylation in tumors was associated with more advanced tumor features, such as high pathologic stage, high grade and clear cell RCC histology, and increased risk of recurrence compared to the low methylation group. These results suggest that tissue changes in promoter methylation in obesity-related genes may provide some biological basis for the association between obesity and RCC outcome, and that
LEPR may be an independent prognostic indicator of recurrence in RCC patients. Further research in larger study population and functional studies are warranted to validate our findings and to elucidate the underlying causal mechanisms.
Dr. Albert Roh[/caption]
Albert Roh MD
Radiology Resident
Maricopa Integrated Health System
MedicalResearch.com: What is the background for this study?
Dr. Roh: Obesity is well documented to be associated with many medical conditions. Currently, obesity is defined as body mass index (BMI) over 30 kg/m^2. Although simple to calculate and relatively accurate, BMI has its limitations. BMI does not factor in the subject’s body type or fat distribution pattern. For example, a muscular subject and a fatty subject may both have BMI of 30 and be considered obese, although the muscular subject would not be predisposed to the comorbidities associated with obesity. Similarly, two subjects may have the same BMI but have different fat distribution patterns: “apple” with fat distributed primarily on the chest/abdomen and “pear” with fat distributed on the hips. The “apple” fat distribution correlates better with the comorbidities associated with obesity.
Dr. Jed Friedman[/caption]
Jacob (Jed) E. Friedman, Professor, Ph.D.
Department of Pediatrics, Biochemistry & Molecular Genetics
Director, NIH Center for Human Nutrition Research Metabolism Core Laboratory
University of Colorado Anschutz
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Scientists have long established that children who are breastfed are less likely to be obese as adults, though they have yet to identify precisely how breastfeeding protects children against obesity. One likely reason is that children who are breastfed have different bacteria in their intestines than those who are formula fed.
The study, published Monday in the American Journal of Clinical Nutrition examines the role of human milk hormones in the development of infants’ microbiome, a bacterial ecosystem in the digestive system that contributes to multiple facets of health.
“This is the first study of its kind to suggest that hormones in human milk may play an important role in shaping a healthy infant microbiome,” said Bridget Young, co-first author and assistant professor of pediatric nutrition at CU Anschutz. “We’ve known for a long time that breast milk contributes to infant intestinal maturation and healthy growth. This study suggests that hormones in milk may be partly responsible for this positive impact through interactions with the infant’s developing microbiome.”
Researchers found that levels of insulin and leptin in the breastmilk were positively associated with greater microbial diversity and families of bacteria in the infants’ stool. Insulin and leptin were associated with bacterial functions that help the intestine develop as a barrier against harmful toxins, which help prevent intestinal inflammation. By promoting a stronger intestinal barrier early in life, these hormones also may protect children from chronic low-grade inflammation, which can lead to a host of additional digestive problems and diseases.
In addition, researchers found significant differences in the intestinal microbiome of breastfed infants who are born to mothers with obesity compared to those born to mothers of normal weight. Infants born to mothers with obesity showed a significant reduction in gammaproteobacteria, a pioneer species that aids in normal intestinal development and microbiome maturation.
Gammaproteobacteria have been shown in mice and newborn infants to cause a healthy amount inflammation in their intestines, protecting them from inflammatory and autoimmune disorders later in life. The 2-week-old infants born to obese mothers in this study had a reduced number of gammaproteobacteria in the infant gut microbiome.
Dr. Corby Martin[/caption]
Dr. Corby K. Martin PhD
Department/Laboratory:
Ingestive Behavior Laboratory
Director for Behavioral Sciences and Epidemiology
Pennington Biomedical Research Lab
Baton Rouge, LA
MedicalResearch.com: What is the background for this study? What are the main findings?
Dr. Martin: We know that calorie restriction extends the lifespan of many species and in humans calorie restriction or dieting might extend our healthspan, which is the length of time that we are free of disease. It is possible that more healthy weight or mildly overweight people might calorie restrict to improve their health, and one concern is the possible negative effects of calorie restriction on the quality of life of these individuals.
This study tested if 2 years of calorie restriction affected a number of quality of life measures compared to a group that did not calorie restrict and ate their usual diet and did not lose weight. People who enrolled in the study were normal weight to mildly overweight. The study found that calorie restriction improved mood, reduced tension and improved general health and sexual drive and relationship (a measure of sexual function) over two years. Further, the more weight that people lost, the greater their improvement in quality of life.
Dr. Ashley Kranjac[/caption]
Ashley Wendell Kranjac, PhD
Department of Sociology and
Kinder Institute for Urban Research
Rice University
Houston, Texas and
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Dr. Robert Wagmiller[/caption]
Robert L. Wagmiller, Jr.
Associate Professor
Department of Sociology
Temple University
Philadelphia, PA 19122
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: The Center for Disease Control recently reported a decline in child obesity amongst 2-to5-year old children between 2003/4 and 2011/12 (see, Ogden et al. 2014). We aimed to identify the sources of this decline because this change occurred in a relatively short period of time. What we found is that the decline in obesity did not occur due to the things that you might expect like changes in physical activity or dietary practices (although there were some differences in these factors across years). But, rather, what we found is that because there were differences in obesity rates for the youngest and oldest children in this age range in 2003/4, but not in 2011/12, that the decline in obesity exists. In other words, because the oldest children in 2003/4 had significantly higher obesity rates than the youngest children in this time period, but this effect is not observable in 2011/12, we see a decline in obesity.
Evelyn Parr[/caption]
Evelyn Parr
Research Officer / PhD Candidate | Centre for Exercise and Nutrition
Mary MacKillop Institute for Health Research
Australian Catholic University
MedicalResearch.com: What is the background for this study? What are the main findings?
Response: Results from previous investigations suggest that compared to a healthy 'control' diet, increased consumption of dairy foods in an energy restricted diet lead to improved body composition (i.e., a loss of fat mass and the maintenance of lean mass).
We investigated the effects of manipulating the type of dairy foods (i.e., low- or high fat) within high protein, energy restricted diets on body composition and selected health parameters. Eighty-nine middle-aged (35-59 y), male and females who were overweight or obese completed a 16 week intervention comprising 3 d/wk supervised resistance training and 4 d/wk unsupervised aerobic -based exercise (i.e. walking). During this time they consumed a diet that was energy restricted by 250 kcal/d comprising either
1) high protein, moderate carbohydrate (4-5 normal fat dairy product servings),
2) high protein, high carbohydrate (4-5 low-fat, carbohydrate sweetened dairy product servings or
3) a control diet of moderate protein, high carbohydrate diet (1-2 dairy servings).
We found that in the face of energy restriction, when protein intakes were above the recommended daily intakes (>0.8 g/kg body mass) and regular exercise was completed, there was no difference in the loss of fat mass (~8 kg) when participants consumed 4-5 serves of dairy products in either low- or high-fat. Furthermore, participants maintained lean (muscle) mass throughout the energy restricted period.
