Tuesday, August 23, 2011

New Treatment for Chronic Lymphocytic Leukemia

Researchers at the University of Pennsylvania have recently reported a potential breakthrough in the treatment of chronic lymphocytic leukemia (CLL), a cancer of B-cells of the immune system. The researchers removed some T-cells from three patients with CLL and genetically modified them to recognize the leukemic tumor cells. When the modified cells T-cells were re-infused into the patients they vigorously attacked the leukemic tumor cells, sending the cancer into complete remission in two patients and significantly improving the condition of the third patient. Significantly, the genetically modified T-cells underwent clonal expansion within the patients, leading to over a 1000-fold expansion of activated T-cells that lasted more than six months.

These results should be viewed as preliminary. Only three patients have been treated so far and the long-term efficacy of the technique is not yet known. Nevertheless, the idea of activating a patient’s own immune system to attack specific cancer cells is extremely attractive, and might be applicable to other cancers as well. We’ll be keeping an eye on this.

Sunday, August 21, 2011

Tall Women and Cancer Risk

Tall women are at increased risk for cancer, according to the results of a recent study of over a million middle-aged women. The overall risk of cancer is about 16% higher for every 4-inch increase in height over 5’0”. The relationship between height and cancer is independent of socioeconomic status, alcohol intake, level of physical activity, and body mass index. No one knows what IS causing the increased risk for taller women, but researchers speculate that it may have something to do with hormonal influences early in life or with the fact that taller women have more cells (and more stem cells) than shorter women, leading to more opportunities for cellular mutations. But that’s just speculation.

Before you taller women get too concerned by these findings, understand that the study reports relative risk – the risk for taller women compared to the risk for the shortest group of women. For most cancers, the actual number of cases per year is fairly low. For example, I calculate that in this study there were about 7 cases of cancer per year per 10,000 women who were under 5’1”, versus about 8 cases per year per 10,000 women who were four inches taller –- there’s your 16% increase.

Thursday, August 11, 2011

Fetal Gender Determination

The gender of a fetus can be determined fairly accurately using only a small sample of maternal blood, according to an analysis published recently in JAMA. But it's only about 95% accurate after seven weeks and 99% accurate after 20 weeks. That's a far cry from the 99.9% accuracy by five weeks of pregnancy claimed by Acu-gen Biolabs, the makers of the now discredited Baby Gender Mentor, back in 2005.

Fetal gender determination before 20 weeks of pregnancy relies on analyzing the small amount of fetal DNA that appears in maternal blood. If Y-chromosomal material is present then the fetus must be a male (XY); if not, then the fetus must is a female (XX).

One note of caution; the fetal DNA in maternal blood must be amplified before testing because it is present in such small quantities in early pregnancy. The authors found that one of several DNA-amplification methods, called “real-time quantitative polymerase chain reaction” (RTQ-PCR), gave the most reliable results by 7 weeks.

Ultimately, DNA testing of maternal blood will probably supplant ultrasound (a.k.a. sonography) for gender testing, because ultrasound isn’t even very reliable until fairly late in gestation. However, DNA testing is still new and not yet reimbursed by insurers. Perhaps that will change with time.

Monday, August 8, 2011

The Human Population

When in history did the human population begin to increase rapidly? Which countries are now encouraging their citizens to have more babies rather than fewer, and why? How does population age structure affect a country’s economic wellbeing? What affect does level of educational attainment have on human population trends? What are the advantages and the disadvantages of current trends toward urbanization in many countries?

These and other interesting questions are explored in a special section of the July 29th issue of Science. It’s a great resource for those interested in trends in human population and how those trends may affect our quality of life in the coming century.

Reference: Special Section: Population. Science July 29, 2011, pp. 538-594.

Friday, August 5, 2011

Biofuels – Not Yet Ready for Prime Time

There’s a lot of interest in the possibility of producing fuels from plant materials (biofuels) as a substitute for fossil fuels. Unfortunately, it’s proven to be more difficult to accomplish than anticipated, according to an article in Scientific American this month. The only so-called “success” so far is ethanol derived from corn, but that’s because corn-based ethanol production is highly subsidized by the government. More than a quarter of the U.S. corn crop now goes to ethanol production. Nevertheless, corn-derived ethanol is not going to solve our energy problem – it diverts too much corn from food products, it is not particularly energy-efficient, and it is not capable of matching the sheer volume of gasoline the U.S. uses per year. At best, corn-derived ethanol is likely to remain a fuel supplement, capable of supplying only a fraction of our fuel requirements. Several attempts to produce ethanol from biomass waste material or wood chips on a commercial scale have failed – the technology just isn’t good enough yet. And the production of fuel oils using algae or bacteria have also proven to be too costly yet - fuel oil at over $400 a gallon, anyone?

This does not mean we should give up. Most advances in science are incremental – one little step at a time. Perhaps there will even be a major breakthrough, like a bacterium specifically engineered to make and excrete fuel oil. Just don’t expect to see a biofuel-powered car in your local showroom any time soon.

Reference: Biello, David. The False Promise of Biofuels. Scientific American Aug. 2011, pp. 58-65.