China's Future Water Shortage

China is depleting its underground water reserves in an effort to increase its agricultural productivity, according to a news article in Science magazine. Hundreds of thousands of wells were drilled in the North China Plain over the past 40 years, turning the plain into a fertile corn- and wheat-farming region. But the water table in the North China Plain is now falling at an alarming rate. Many of the wells are expected to run dry within the next couple of decades, putting at risk China’s ability to feed its growing population.

Water in deep underground aquifers exchanges only slowly with surface water. According to experts, some of the water now being drawn out in the North China Plain aquifer has been underground for 30,000 years. It might be that long again before it could be replaced naturally. In other words, water in deep underground aquifers should be thought of as a non-renewable resource, like coal, oil, and gas.

Reducing the Duration of Muscle Cramps

The cause of muscle cramps during extreme exercise is somewhat of a mystery. The usual explanation is that dehydration-induced electrolyte imbalance leads to inappropriate firing of the motor neurons to the muscle. The usual treatment is physical stretching until the cramping stops, followed by rehydration with salts and water to restore fluid and electrolyte balance.

Is there anything that can shorten the duration of a cramp? Apparently there is – pickle juice! A recent study shows that the duration of cramps deliberately induced in a muscle in the big toe is reduced 37% by drinking about 2 ½ tablespoons of pickle juice as soon as the cramp starts. (Cramps were induced in a muscle in the big toe, because deliberately inducing muscle cramps in a larger muscle was thought to be too painful.)

Interestingly, the pickle juice worked within 1 ½ minutes – too fast to be due to replenishment of body fluids or salts. Researchers speculate that the acetic acid in pickle juice triggers a neural reflex originating in the esophagus or stomach, which somehow inhibits the excessive firing rate of motor neurons to the cramping muscle.

Whether pickle juice will reduce the duration of cramps in major muscle groups in athletes remains to be seen.

Teens and the Rhythm Method of Birth Control

According to a recent government survey of teen sex entitled “Teenagers in the United States: Sexual Activity, Contraceptive Use, and Childbearing, National Survey of Family Growth, 2006-2008”, teens aged 15-19 increasingly are relying on the rhythm method for birth control. Among sexually active teens, 17% reported using the rhythm method in 2006-2008, compared to just 11% in 2002.

The rhythm method, also known as periodic abstinence, is moderately effective as a birth control method. Approximately 25% of women who rely on the rhythm method will become pregnant in a year. (Approximately 85% of women who use no birth control method at all will become pregnant in the first year.) However, the rhythm method is much less effective than birth control pills or condoms, which have failure rates of less than 5% per year if used properly.

The new findings coincide with both an increased number of teen pregnancies and an increased acceptance of unwed pregnancy by teens. In the survey, 2/3 of all teens said they agreed or strongly agreed with the statement, “It is OK for an unwed female to have a child”. Sex-education messages to teens may have to change if this trend is to be reversed.

For more on birth control methods, see a previous blog post titled "Birth Control Method Failures."

Do Skin Sutures Need to be Kept Covered and Dry?

I’ve always heard that skin sutures should be covered and kept dry for a couple of days in order to prevent infections – at least that’s the usual standard medical advice. But does getting recent sutures wet really lead to more infections?

To answer that question, a couple of years ago a team of Australian researchers randomly assigned over 850 patients who needed skin sutures into one of two groups. Patients in one group were asked to keep their sutures dry and covered, while the patients in the other group were allowed to remove their bandages and get their sutures wet within the first 48 hours.

The results of the study indicated that there were no differences in the incidences of infection between the two groups. The results indicate that it would be perfectly okay to take a shower without increasing the risk of infection of recent skin sutures. But I wouldn't suggest going swimming in a scummy lake or river....

Improving Rice Yields, Feeding the World

Two groups of scientists working independently have identified a variant of a gene in rice that can increase rice crop yields by 10%, according to a news report in Science. Neither group knew of the other’s work until their work was near completion, but when they learned of each other’s work they agreed to publish simultaneously.

Rice is a staple of a large fraction of the world’s population. Breakthroughs such as this one will help improve crop yields and feed the still-rising world population. They’re made possible by modern DNA technology and genetic engineering – techniques that allow crop scientists to sequence genomes, identify specific genes with specific actions, and then splice the genes into other plants of interest.

Beating the EPO Blood Doping Test

Synthetic erythropoietin, called EPO, was widely used by endurance athletes in the 1990s to boost red blood cell production and blood oxygen carrying capacity. The use of EPO declined after 2000 when the World Anti-Doping Agency (WADA) developed a test to detect EPO in urine.

But now, WADA believes that athletes could be beating the current EPO urine tests by “microdosing” – injecting very small (micro) doses of EPO at night. EPO is excreted so rapidly into the urine that most of an injected dose will be eliminated from the body within eight hours. Thus, microdosing is likely to go undetected as long as urine samples are not demanded in the middle of the night.

Microdosing works because the effects of the erythropoietin outlast the hormone itself. Researchers now know that even such small, intermittent doses of EPO will boost the body’s production of red blood cells significantly over time. They aren’t publishing their dosage information to avoid providing a recipe for blood-doping, but they suspect that athletes already know.