These toxins may destroy oocytes, thereby shutting down estrogen synthesis. This is why women who smoke heavily sometimes have an early menopause and are especially prone to bone loss and vertebral fractures. Another area of research in Dr. Grynpas' laboratory is the effect of microgravity on the skeleton. Working with the Canadian Space Agency, NASA and French collaborators on some Russian satellites, Dr. Grynpas and his associates noted that when an individual goes into space all the body tissues are affected. After a period, all body tissues, except the skeleton, adapt to the space environment.
Russian astronauts continue to lose bone at an accelerated rate up to one year after being in space.
This may be due, in part, to the finding that bone formed in space has an architecture and a mineralization profile that is different to that of bone formed on earth. It is not yet clear what the long-term effect of longer space missions will be on the human skeleton, following the return of the astronauts to earth. Dr. Grynpas is also looking at abnormal mineralization, a key factor in the pathogenesis of human kidney stones. One of his colleagues, Dr. Bushinsky, has bred hypercalciuric rats or rats that excrete a large amount of calcium. These animals constitute the first animal model of spontaneous kidney stone formation or nephrolithiasis.