Sunday, December 28, 2008

Exercising Your Head Cold

When you catch cold, should you continue your usual exercise routine or just stay at home and rest?

According to a pair of articles published about 10 years ago, maintaining your usual exercise regimen may be good for you when you have a cold, or at least it will do no harm. A typical head cold with a runny nose and sneezing does not affect lung function or exercise capacity. And although exercise doesn’t actually speed recovery time, people who continue to exercise during a head cold tend to report that they feel better than people who don't exercise. So the next time you catch a cold, go ahead and continue doing whatever exercise you enjoy doing.

"Effect of rhinovirus-caused upper respiratory illness on pulmonary function test and exercise responses". Weidner TG et al. Med. Sci. Sports Exerc. 29:604-609, 1997.
"The effect of exercise training on the severity and duration of a viral upper respiratory illness". Weidner TG et al. Med. Sci. Sports Exerc. 30:1578-1583, 1998.

Friday, December 19, 2008

Detecting Protein Markers of Disease

Certain diseases are characterized as having specific abnormal proteins circulating in their blood. These proteins could serve as markers of the presence of the disease. However, the current clinical laboratory tests for these proteins are expensive, making screening millions of people for these diseases impractical. Generally, the only people who are tested are those who are at risk or who are already suspected of having the disease.

A technique just now being developed would make testing for the presence of abnormal plasma proteins easy, quick and cheap. The technique is based on glass and plastic microfluidic chips that can test for dozens of proteins in a single drop of blood, in just minutes, for pennies per test. The new technique is described in the Dec. 19 issue of Science.

Thursday, December 18, 2008

Incentives for Organ Donations

There are now over 100,000 patients waiting for an organ transplant. Over 6,000 of them will die this year because they will not find a suitable organ in time. The problem, as discussed in Human Biology 5th ed. (pp. 368-369), is simply too few available organs for too many patients. Aside from the fact that finding a good match among unrelated donors is relatively rare, healthy people are often reluctant to donate an organ for emotional reasons and there is no financial incentive for organ donations. In fact, current federal law states that a person can go to jail and be fined $50,000 if “valuable consideration” is given to a donor. The law was meant to discourage commercial trafficking in human organs (considered to be exploitive of the poor), but it has also had a chilling effect on altruistic giving.

But that may soon change. Senator Arlen Specter of Pennsylvania will introduce a bill next year that would allow states to offer certain “incentives” to donors and their families, such as tax credits, contributions to 401K retirement plans, and tuition vouchers. The bill still would still prohibit the direct buying and selling of organs, however, so you won’t be able to buy a kidney on eBay any time soon.

One patient’s emotional odyssey as her kidneys began to fail is described in “Desperately Seeking a Kidney” published two days ago in the New York Times. It might make an interesting additional reading assignment for your students.

Wednesday, December 17, 2008

Frozen Embryo Dilemma

Fertility treatments and IVF procedures generally produce more viable embryos than are needed in order to achieve a successful pregnancy. So after a couple has a child by IVF, they must decide what to do with the “leftover” embryos. There are at least five choices: 1) freeze and save them for several years in case they choose to have more children, 2) discard them, 3) donate them for research, 4) donate them to another couple, and 5) leave them frozen until some other decision is made.

A recent survey published in the journal Fertility and Sterility (online Dec. 5) indicates that the decision is a difficult one, even for couples that do not want any more children. Over 40% would not feel comfortable discarding the embryos. And even though they no longer needed them for themselves, over 50% would not consider donating their embryos to another couple. Common reasons given were because they wouldn’t want their child brought up by another couple or because of the fear that their child might meet an unknown sibling someday. Forty percent would consider donating their unused embryos for research, but that option is not available at all IVF clinics. Faced with what they view as unacceptable options, twenty percent say they will keep the embryos frozen indefinitely. However, frozen embryos may not be viable after several decades, so this may ultimately be a decision to let the embryos die.

There are now more than 400,000 frozen embryos at IVF clinics. The authors of the survey suggest that potential parents need to be counseled thoroughly about the choices ahead of them before they choose IVF, not after.

What would your students choose to do if they had leftover embryos?

Tuesday, December 9, 2008

Alzheimer's Disease Linked to a Virus

Alzheimer’s disease is a debilitating disorder of the elderly characterized by severe, progressive loss of memory, confusion, irritability, and withdrawal. The disease develops because amyloid plaques accumulate in the brain, interfering with neural transmission. But why do these plaques develop in some elderly persons but not others?

A recent paper in the Journal of Pathology (217:131-138, Jan. 2009) offers some tantalizing clues. It appears that two factors may be involved; 1) a genetic predisposition to Alzheimer’s disease, and 2) chronic infection of the brain with the same virus that causes cold sores; Herpes simplex type 1. The herpes virus is present in the brains of a high proportion of elderly persons. In the absence of the genetic predisposition to Alzheimer’s the virus doesn’t seem to do much. But in elderly patients with the genetic risk factor for Alzheimer’s, the virus is associated with amyloid plaque accumulation and may in fact be the cause of the plaque formation. If this turns out to be correct, Alzheimer’s disease may some day be preventable with a vaccine.

I am reminded of another chronic disease - peptic ulcers - that turned out to be caused by an infection, in this case by a bacterium called Helicobacter pylori (see Human Biology, 5th ed., p. 328).