Julia Levy

Microbiology and Immunology

Co-discovered photodynamic anti-cancer and ophthalmology drugs, co-founder of the company QLT Inc.

"The most important thing: Never shut off your options. You never know what the next year is going to bring. If you leave your options open, then when something happens you know, ‘That’s where I want to go.’ And you do it! Never box yourself in."

Microbiologists research such areas as bacteria, fungi, viruses, tissues, cells, pharmaceuticals and plant or animal toxins. Julia Levy is a microbiologist and immunologist, someone who studies the human immune system, the collection of molecules and cells that help the body fight off disease. Together with colleagues from UBC she develops drugs that are unique because they are photosensitive, which means that upon being exposed to light they change in some way that makes them toxic to cells. This photodynamic therapy can be used to treat lung cancer and other diseases such as AMD.

AMD affects a very tiny part of the eye called the macula, the “business part of the eye,” as Levy calls it. The eye is like a camera, with a lens at the front and a sort of “film” at the back called the retina. The retina’s job is to convert light into nerve signals for the brain to turn into images. The macula is just a few square millimetres near the middle of the retina, but it has millions and millions of finely tuned light receptor cells — many more per unit area than the rest of the retinal surface. It’s the part of the eye where we turn our focus to read and write, to draw or work with our hands, to watch TV, to prepare and eat food or to recognize faces, among many other activities that require the discrimination of fine detail.

In people with AMD, microscopic blood vessels grow abnormally and invade one of the membranes at the back of the retina, where the vessels start leaking. “The macula is the only part of your body where if even one micron (one-millionth of a metre) of it is hurt, your vision is damaged,” says Levy. Most other parts of your body can sustain damage in large chunks and work just fine, but not the macula. It’s one of the most incredible parts of the body.

For people with AMD, the centre of their vision is blurred or distorted or things appear odd in size or shape. For instance, things that are normally straight, such as doorways or telephone poles, might seem bent or crooked. As the disease gets worse, a blank patch or dark spot forms in the centre of their sight. This makes activities like reading, writing and recognizing small objects or faces very difficult. Nobody knows why AMD occurs, but there seems to be a genetic component; it runs in families. Europeans are more prone to get it than Asians or Africans. It is also related to age; about half of people over 85 have it.

How Visudyne (verteporfin) works. Click to Enlarge.

1. Photodynamic drug Visudyne injected into the bloodstream through the patient’s arm.

2. Low density lipoproteins (LDL) are large molecules that carry fatty material in blood. They form a chemical complex with the drug to take it to all parts of the body.

3. The verteporfin molecule, the active ingredient of Visudyne developed by Levy and other scientists at QLT. This molecule changes when exposed to red light.

4. The drug accumulates in the abnormal blood vessels of the diseased macula, part of the retina at the back of the eye, where new blood vessels are growing improperly, causing the disease. The abnormal vessels attract and absorb the LDL-Visudyne complex.

5. Because new blood vessel cells grow faster than normal cells, they invade one of the membranes of the retina and start leaking. This is the cause of one form of macular degeneration disease. Their faster growth rate also makes them take up verteporfin about 10 times more quickly than normal cells.

6. About 10 or 15 minutes after the injection, doctors shine cool red laser diode light into the eye for about 90 seconds. The light has a wavelength of 690 nanometres, which is the optimum shade of red for activating the verteporfin, creating free oxygen molecules. The oxygen reacts with the abnormal blood vessel cells and effectively “burns” them up.

7. The abnormal vessels are destroyed.

All the science for Visudyne is done in Vancouver, but the active ingredient is made in Edmonton, Alberta, and then modified in Japan to make it soluble. Finally, the product is bottled and labelled in the United States. More of this process will soon be moving to Vancouver.


ACTIVITY

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MYSTERY

Levy says that although researchers know a lot about the biology of cancer cells, how cancer cells develop is still one of the biggest mysteries around.

Explore Further

Wikipedia entry on Macular Degeneration

 

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