Sound Medicine -- February 8, 2003

Gene therapy from a vector lab

Cancer diagnosis with combined PET/CT scans

Our most basic biological clock

Gene therapy from a vector lab

For patients with a genetic immune disorder or cancer, gene therapy is the miracle they've hoped for. So it was bad news last month when the Food and Drug Administration suspended 27 gene therapy clinical trials after a second child who had participated in a French clinical trial developed a leukemia-like condition.

We talk about this suspension and hear the current status of gene therapy research from Dr. Kenneth Cornetta, coordinating director of the National Gene Vector Laboratories, an important body in the gene therapy field based quietly on the Indiana University School of Medicine campus. Dr. Cornetta's lab -- along with two others at Baylor University in Texas and City of Hope National Medical Center in California -- creates vectors, altered viruses which act as transport mechanisms necessary for gene therapy. Dr. Cornetta also is chairman of the department of medical and molecular genetics and professor of medicine at the IU School of Medicine.

Gene therapy works for a variety of diseases using the same principal: the transport of genetic material into a cell so the body can manufacture the correct protein and remedy a disease. Dr. Cornetta describes a "vector" as a modified virus -- one in which the disease-causing genes have been replaced with therapeutic genes. The vector functions to transfer healthy genetic material into cells with defective or missing genes. The "bubble baby syndrome" is one condition treated with gene therapy, he says, but it's also used in cancer and HIV treatments.

Dr. Cornetta discusses in detail the French trial, which used the well-known retroviral mediated gene therapy technique, and why its results are so puzzling. He talks about regulations for running gene therapy trials and the research in blood and bone marrow diseases underway at the National Vector Lab.

Resources:

The Human Genome Project offers an excellent primer on gene therapy.

Read the New York Times article on the FDA's suspension of gene therapy trials. (Registration required.)

The NIH provides a good description of the work being done at the National Vector Lab.
For researchers, the National Gene Vector Lab provides vectors and other support.

Find out how clinical trials work at the NIH's ClinicalTrials.gov Web site.

Cancer diagnosis with combined PET/CT scans

Medical imaging technology now combines two familiar systems -- positron emission tomography and computed tomography -- to give physicians the closest thing to 20/20 diagnostic vision. The IU School of Medicine was one of the first three institutions in the U.S. to install a PET/CT fusion-imaging system. We learn how the device works from James Fletcher, MD, director the Clinical PET Imaging Center at IU.

Dr. Fletcher provides a little history on PET and CT technology, explains how the technologies safely use radiation, and differentiates their purposes -- the CT for imaging human structure and anatomy and the PET for biochemical functions and metabolism. The combined device fuses images that provide more precise and accurate diagnoses. Cancer diagnosis and management are the primary applications, he explains, but PET/CT scans can also be useful in diagnosing neurological disorders, dementia and coronary disease.

Resources:

To see how PET and CT images are combined, click here to view image samples.

Dr. Fletcher has prepared a concise primer on PET/CT technology. Find it here.

Siemens AG, manufacturer of PET/CT devices, provides photos of the machinery as well as sample tissue scans.

Read about the combined PET/CT scanner now housed at the IU School of Medicine.

Our most basic biological clock

The term "biological clock" is usually used metaphorically in reference to a woman's childbearing years. But in actuality, everyone may have an internal timer for regulating the body's reproductive, health and survival instincts. A husband-and-wife team at Purdue University say they have proof that people have such a a biological clock. It's a protein that determines periods of activity and inactivity for every cell in our bodies. Dr. James Morre is a distinguished professor of medicinal chemistry in Purdue's School of Pharmacy and Dr. Dorothy Morre is professor of foods and nutrition in Purdue's School of Consumer and Family Sciences.

James Morre says the protein is analogous to the pendulum of the biological clock, something that drives the gears for every individual cell. Understanding this protein allows researchers to "reset" or synchronize cells in culture.

A simple application might be to reset our clock to overcome the effects of jet lag. More formidably, this novel protein could be exploited to treat cancer cells "at the right time," when cancerous tissue is susceptible to a drug, for example, and healthy cells are resistant. The Morres are currently trying to answer many basic scientific questions about this protein, such as how does our body keep running?

Resources:

Read news about the Morre's research, including an abstract of the published article, from the Purdue news service.

The Morre's article "Biochemical Basis for the Biological Clock" is published in the journal Biochemistry.

 

Is there a medical topic you'd like us to cover? Reach us by email: soundmed@iu.edu
or by phone:
(317) 274-4848.

Medical experts recommend at least 60 milligrams of vitamin C everyday. However, some people require higher quantities of vitamin C, depending on their lifestyle. Which of the following people require higher quantities of vitamin C in their diet?

A. Pregnant women
B. Smokers
C. Laborers

Find out!

Medical mystery — What makes for different eye color?

We all know that eye color is an inherited trait. But what causes people to have different colored eyes in the first place? And why do babies' eyes change color in the first year of life?

Find out!

Did you know that fewer than 10 percent of children who should be restrained in booster seats ride in one? The National Highway Traffic Safety Administration (NHTSA) is campaigning to get all kids restrained properly in cars. NHTSA recommends that children who have outgrown child safety seats be properly restrained in booster seats from about age four and 40 pounds to at least age eight or 4'9". In Indiana, legislation is before the General Assembly that would make it law for children to ride in booster seats until age eight.

A child is ready for standard seat belt use when he can sit all the way back in the seat, his knees bend at edge of seat, and his feet touch the floor. In addition, the shoulder belt should fit across the shoulder and the lap belt should fit low over the hips.

Other statistics from the NHTSA:

• Children age two to five who are prematurely graduated to safety belts are four times more likely to sustain a serious head injury than those restrained in child safety seats or booster seats.
• Research shows child safety seats reduce fatal injury by 71% for infants (under one year old) and by 54% for toddlers (one to four years old).
• In 2001, 84% of infants involved in a fatal crash who were restrained in a child safety seat survived, compared with 42% of those who were unrestrained.

The 4 stages for child restraint are:

1. Rear-facing infant seats in the back seat from birth to at least one year old and at least 20 pounds.
2. Forward-facing toddler seats in the back seat from age one to about age four and 20 to 40 pounds.
3. Booster seats in the back seat from about age four and 40 pounds to at least age eight, unless 4'9".
4. Safety belts at age eight or older or taller than 4'9". All children 12 and under should ride in the back seat.

For more information about safety seats or to find out if you're restraining your child properly, contact the IU School of Medicine's Automotive Safety Program at (800) KID-N-CAR (543-6227).