Meteorites, MS and the Mississippi River

• A crater caused by the impact of a meteorite that was about 19 miles across was recently discovered in Greenland. It appears to be the largest and oldest such crater ever found, and it left a dent in the earth 310 miles wide. A meteorite striking the earth today would wipe out all higher life forms – fortunately, this one happened 3 billion years ago. (Science News, Sept. 22, 2012; Earth and Planetary Science Letters, July 1, 2012)

• About 400,000 people in the U.S. have multiple sclerosis (MS), a neurological disorder characterized by loss of the insulating sheath (myelin) around the long extensions (axons) of certain kinds of neurons in the brain and spinal cord. This sheath ensures that signals can be carried uninterrupted from one neuron to another along their long extensions, which may be over a foot long. When the sheath is damaged, the long extensions may short-circuit causing a loss of normal muscle action. There is no cure for MS at this time, but nine different drugs are available to treat the symptoms and slow progression of the disorder.

It is generally believed that the immune system in a person with MS malfunctions, and antibodies are produced against the material making up the insulating sheath. As a result, inflammation and loss of sheath material occurs. No one knows why this happens although at least three factors may play a role. For example, genetic factors can be involved – if a person has a close relative with MS, he or she is at slightly greater risk of developing MS. Environmental factors could contribute, for the disorder occurs more often in people living farther from the equator, which raises the question as to whether vitamin D is a factor, since sunlight is required for skin to produce the vitamin. A third possibility is that an infectious agent, such as a virus or bacterium, might trigger MS. A recent study revealed two distinct sets of certain molecules in the blood of MS patients. One set was linked to patients with a higher risk for relapse, referred to as MSa patients, while the other set was associated with patients where MS symptoms progressed more slowly (MSb patients). Now physicians can better evaluate patients and tailor their drug regimen depending on whether they show MSa or MSb blood. While the search goes on for the cause and cure of MS, the fact is that with the drugs now available, people with MS usually live a normal life span. (Science Translational Medicine, Sept. 26, 2012; Science Daily, Sept. 26, 2012;;; other sources)

• Environmental changes are occurring near New Orleans that have impacts on the delta rivaling those of the BP pollution disaster. Nitrogen and phosphorous from farms of the Midwest are being carried by the Mississippi River into the Gulf of Mexico. These excess nutrients caused algae to bloom to a point where they deplete the oxygen level in the offshore ocean, leading to a “dead zone” that kills off sea life. The ecological disaster zone has now grown to 6,700 miles, an area larger than the state of Connecticut. This is likely the unintended consequence of a too liberal use of crop nutrients. (The Economist, June 23, 2012)