LITHIUM: NOT SO BAD TO THE BONE
Researchers discovered several years ago that lithium – commonly used in treating bipolar disorder – has a beneficial effect on bone healing.
So scientists at Sunnybrook Research Institute Dr. Diane Nam and Dr. Cari Whyne have been working together to find how lithium can best be used in healing bone fractures.
"As a clinician, I want to know when to give it, how much to give and for how long," explains Dr. Nam. "You have to figure out the practicality of an existing drug if you are going to use it for a different reason."
When a bone breaks, the body immediately starts the healing process. A bridge of cartilage forms, and, soon after, this is replaced with new bone by mature bone-forming cells in order to complete healing.
Lithium seems to have an effect on the Wnt signalling pathway, a biochemical pathway that is activated during fracture repair. "Lithium changes the pathway and speeds up the process of this conversion to mature bone-forming cells, which are the cells that actually create new bone," Dr. Nam explains.
Timing, however, is critical. The Sunnybrook researchers found that starting a two-week treatment with a low dose of lithium seven days after a fracture resulted in a 46 per cent better bone mend.
Dr. Nam and Dr. Whyne will next look at how lithium may also improve healing in bone fractures of elderly patients with osteoporosis, a disease that affects bone density and increases risks of fractures. Statistics show that one in three women experience osteoporosis-related fractures, and one in five men.
"Patients at higher risk of impaired healing, such as those with osteoporosis, could significantly benefit from lithium after a fracture," says Dr. Nam. "Osteoporotic fractures are steadily increasing as our population ages, and this is a very big problem we face." •
ARTERIES KEEP IT FLOWING
Having diabetes puts patients at a higher-than-average risk of developing heart disease. A team at Sunnybrook's Schulich Heart Centre is ensuring that diabetic patients receive the most effective treatment, should they need open heart surgery.
Open heart surgery, or coronary artery bypass grafting, reroutes blood around blocked arteries, increasing blood flow to the heart muscle tissue. There are a couple of ways to approach the surgery: by grafting a healthy artery from the wrist or forearm, or a vein from the thigh, to a blocked heart artery.
Current practice favours using the vein, but new research shows that for diabetic patients with multiple blocked heart arteries, an artery from the wrist or forearm is a much better option. A recent clinical trial showed that five or more years after heart surgery, less than 5 per cent of patients with an artery from their wrist had blocked grafts. In the vein group, it was more than 25 per cent with blocked grafts.
"The artery from the forearm or wrist has a lot of things that make it attractive from a surgical perspective," says Dr. Stephen Fremes, holder of the Bernard S. Goldman Chair in Cardiac Surgery. "It's not delicate. And, as we learned, a significantly better option for diabetic patients."
Dr. Fremes and colleague Dr. Saswata Deb, cardiac surgeon, both hope that the Sunnybrook study will be the push needed for more cardiac surgeons to use arteries over veins in open heart surgery for diabetics. For more than three million Canadians living with diabetes, all facing a greater chance of needing open heart surgery, this is a potentially life-saving game changer. •
UNLOCKING MITOCHONDRIAL MYSTERIES
Studies of our DNA have revealed a lot of useful information about the increased risk a person might have for certain illnesses. Yet much about the genetic nature of illness remains to be discovered.
Researchers at Sunnybrook and the Centre for Addiction and Mental Health are now looking at another piece of the genetic puzzle, the mitochondria. Passed down along our maternal lines, these are the tiny structures present in every cell that turn glucose into the energy our cells need to function. "They are the engine of the body," says Dr. Peggy Richter, head of Sunnybrook's Frederick W. Thompson Anxiety Disorders Centre, "and carry within them their own DNA."
A psychiatrist, Dr. Richter has studied obsessive-compulsive disorder (OCD) – and the genetic mechanisms that could underlie it – for more than 20 years. "Although there is very good evidence to support that OCD is genetically transmitted," she says, "finding major genetic factors has been elusive." That led her to focus on the mitochondria.
"We took another look at genotyping we had done years ago," she explains. Her team looked at markers specifically involved in the energy metabolism systems in human DNA that interact with the mitochondrial genes and found a suggestion of involvement of one gene.
A follow-up study looked at genes involved in energy regulation in greater detail. "We observed a number of minor positive findings for five genes," says Dr. Richter. Encouraged by the results, she will soon start a further study, "where we will look at directly decoding the DNA 'alphabet' in the mitochondria genes letter by letter," she says. "Very few studies have been done like this, and we're very excited."
If specific changes in the mitochondrial genetic code are identified that relate to OCD, it would suggest that the functioning of the body's energy system may be important to developing this chronic illness. •
This content was produced by The Globe and Mail's advertising department, in consultation with Sunnybrook. The Globe's editorial department was not involved in its creation.