April 18, 2008

Aliquots — Research highlights from VUMC laboratories

Featured Image

We welcome suggestions for research to highlight in Aliquots. The items should be primary research articles (no reviews, editorials or commentaries) published within the last two months in a peer-reviewed journal. Please send the article citation (PDF if available) and any other feedback about the column to: aliquots@vanderbilt.edu.

Stuck in the middle

Certain functions, like language, are localized preferentially to one side of the brain. And the outwardly symmetrical brain conceals a number of structural asymmetries as well.

Joshua Gamse, Ph.D., and colleagues are investigating the origins of left-right brain asymmetry in the zebrafish parapineal organ – a cluster of neurons in non-mammalian vertebrates that normally migrates from the center of the brain to the left side and directs asymmetric development of other nearby brain regions. They recently identified a mutant zebrafish strain, named from beyond, in which the parapineal organ is smaller and remains in the center of the brain.

They report in the journal Development that this abnormal symmetry is linked to a mutation in the T-box2b gene, which encodes a transcription factor expressed in the developing parapineal organ. Identification of genes that underlie the development of asymmetry in this tiny region of the zebrafish brain may help direct the search for the origins of asymmetry in the human brain.

— Melissa Marino

How much radiation?

Image-guided radiation therapy (IGRT) has improved accuracy of radiation delivery to tumors. It is used for positioning patients and modifying treatment plans to reflect tumor changes during therapy. But daily X-ray imaging for IGRT introduces additional radiation exposure, a risk for radiosensitive organs like the lens of the eye, bone marrow and reproductive organs. This increased radiation dose to non-target tissues may be of particular concern for pediatric patients.

George Ding, Ph.D., and Charles Coffey, Ph.D., have now developed a method to accurately predict the additional radiation dose from an imaging procedure that uses X-rays. In the March issue of Medical Physics, they describe the new mathematical algorithm and demonstrate how it calculates exact radiation dose to each organ, including the dose to bone marrow. This new method will provide radiation oncologists with the critical information they need to make educated decisions about using X-ray imaging in IGRT.

— Leigh MacMillan

Clear vision of eye disease genes

Identifying gene variants that influence a person’s risk of developing age-related macular degeneration (AMD), the leading cause of blindness in the elderly, could lead to early risk assessments and tailored preventive treatments. Jonathan Haines, Ph.D., and colleagues previously showed that a particular version of the complement factor H (CFH) gene increases risk for AMD. The CFH gene is part of a DNA region that includes five CFH-related genes, and other variations in this “cluster” of genes have been suggested to reduce risk for AMD.

In work led by Kylee Spencer, Ph.D., the researchers tested whether deletion of two CFH-related genes, CFHR1 and CFHR3, was associated with AMD in a Caucasian population of 780 cases and 265 controls, after adjusting for known AMD risk factors – age, smoking and the presence of risk-increasing genes. They report in the April 15 Human Molecular Genetics that CFHR1/CFHR3 deletion reduces AMD risk, and that there are likely additional protective variants in the CFH gene cluster.

— Leigh MacMillan

Bulking up proteins

Patients undergoing chronic dialysis often suffer muscle wasting that eventually leads to their hospitalization or death. Increased protein breakdown, or catabolism, is one contributor, and recent studies have found that supplementing nutrition in these patients increases protein accumulation and muscle mass.

T. Alp Ikizler, M.D., and colleagues examined whether the addition of resistance exercise to oral nutrition supplementation would allow dialysis patients to increase their skeletal muscle mass even further. They analyzed eight chronic hemodialysis patients during two separate dialysis sessions. Their findings, reported in Nephrology Dialysis Transplantation, show that even one session of resistance exercise training increased the anabolic effects of nutritional supplementation. Patients undergoing resistance training had a significantly higher net muscle protein balance compared to those with nutritional supplementation alone. The findings suggest that, in chronic dialysis patients, offering resistance training in combination with nutritional supplementation may be a practical and accessible method for building up protein and increasing muscle mass.

— Susanne Tranguch

Past Aliquots

June 22, 2012
June 8, 2012
May 11, 2012
April 27, 2012
April 13, 2012
March 30, 2012
March 16, 2012