April 14, 2005

New Breast Cancer Treatment on Horizon

Most women are protected from breast cancer by their BRCA genes. But some women have inherited mutations in BRCA genes, giving them about an eighty per cent risk of developing breast cancer. The key to stopping cells with mutated BRCA is a protein called PARP.

Healthy human cells replicate (reproduce); their DNA divides and copies itself. If DNA is damaged before replication, it is usually repaired by PARP. If a cell can't repair it's DNA with PARP, it uses a backup system called combination to fix the damage so it can continue to replicate.

Cells with mutated BRCA genes don't have the backup system of recombination; rely completely on PARP to fix DNA damage. The new treatment uses a chemical that knocks out PARP, making all cells rely on recombination. The breast cancer tumour, that forms from the cells with mutated BRCA cannot perform recombination and is therefore unable to replicate and create new cells. The tumour is then unable to grow and eventually dies.
The other cells in the body are likely to be unaffected by the treatment. Link.

April 12, 2005

Auroras

From the Sun comes an extremely thin electrified gas, known as the solar wind; it blows constantly out from the Sun at 250 miles per second. The Earth's magnetic field provides a shield against the solar wind. Shaped by the solar wind, the magnetic field becomes stretched and pushed into a teardrop-shaped bubble we call the magnetosphere. Some electrically-charged particles from the solar wind penetrate the magnetosphere, collide with the Earth's upper atmosphere, and emit colorful light which we observe as an aurora. The aurora form near-circular bands around both the northern pole (the aurora borealis) and southern pole (the aurora australis).

Recently, researchers were surprised to find that the two aurora are not mirror images of each other, as was once thought. This appears to be caused by fluctations in the tilt of the Earth's magnetic field, and conditions in the solar wind. Link.

April 5, 2005

It depends what you mean by "planet."

In a previous post, I mentioned that astronomers had used an innovative method to, for the first time, observe light from an extra-solar planet. (An extra solar planet is a planet that orbits a star other than our own sun.) This planet orbits the star GQ Lup. There's no question that the object was observed, but there now seems to be a question of whether it's a planet or just a dim star. Why do we think it's a planet? It's 20 times further from it's GQ Lup than Jupiter is from the our sun. It has a mass of 2 or 3 Jupiters, and anything less massive than 13 Jupiters is small enough to be a planet. But here's the problem: the "planet" is bright; GQ Lup is only 156 times brighter than it. And, it's hot; the "planet" is estimated to be 3,000 degrees F. So for now, astronomers are using the term "companion", rather than "planet". Last year, when Sedna was found orbiting our sun out past Pluto, it sparked a debate as to whether Sedna or Pluto were real planets. The whole problem comes back to the basic question that has yet to be answered: what is a planet? Link.