Nontoxic Nanotubes
Nanoparticles could perform promising biomedical tasks, such as ferrying drugs to diseased cells or detecting genetic anomalies [see “Less Is More in Medicine”; SciAm, September 2001]. But researchers fret that these tiny tools could poison the body.
A Stanford University team has done an experiment that may help allay those fears. The researchers injected about 20 micrograms of single-walled carbon nanotubes into mice. The rodents showed no signs of ill effects or any deleterious accumulation of the nanotubes in organs. In fact, after three months, the mice excreted the tubes in their feces and urine. The February 5 Proceedings of the National Academy of Sciences USA published the findings.
Seeking New Life
Constructing artificial organisms is a key goal of synthetic biology, because such customized creatures could be made to perform many useful functions [see “Synthetic Life”; SciAm, May 2004]. In January scientists at the J. Craig Venter Institute in Rockville, Md., reported making all 582,970 base pairs that constitute the genome of the bacterium Mycoplasma genitalium. Now the researchers just have to insert this man-made genome into a cell and see if the cell comes to life—a prospect likely to be achieved within a year, given their previous success with genome swapping among bacteria. To prove that the genome is artificial, the team encoded “watermarks” of amino acids whose single-letter abbreviations spell out the names of the institute and the researchers.
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How Your Job Is Killing You
In the early 1970s a project tracking 18,000 male British civil servants found that the lowest-ranking white-collar workers had the highest rates of premature death. The results of the investigation, called the Whitehall Study, were a surprise, because it turned out that workload or responsibility had little relation to stress levels. Rather it was how much control an employee had over the work he did and how he did it.
In January researchers—following up with the Whitehall II study, begun in the 1980s—unveiled fresh details about the mechanisms underlying the now firmly established links among low job control, stress and high cardiovascular disease. They found that fully a third of an individual’s total risk for heart disease stemmed from stress-related unhealthy behaviors, such as poor diet, smoking and lack of exercise, as well as lifestyle-influenced conditions such as high blood pressure and blood glucose. The other two thirds of risk was attributable to direct biological wear and tear from living constantly in fight-or-flight mode.
Workers with the highest stress levels, for instance, had the lowest heart-rate variability, a measure of heart rhythms controlled by the body’s autonomic nervous system. Chronic exposure to stress hormones weakens the heart’s ability to respond to changing demands, and low heart-rate variability is associated with greater risk of heart attack and lower survival rates afterward. The European Heart Journal published the findings online January 23.
Windy Green Light
The U.S. may finally get its first offshore wind farm. The Cape Wind project, which would place 130 3.6-megawatt wind turbine generators five miles off the coast of Cape Cod, Mass., has endured years of political and environmental opposition [see “Blowing Out to Sea”; SciAm, March 2002]. It recently cleared its biggest hurdle when it got a clean bill of environmental health from the Department of the Interior’s Minerals Management Service. The agency concluded that the farm will have minimal impact on the population of migratory birds, the activity of local sea life and the ocean views of the politically powerful. (It might moderately affect an annual yachting event, however.) Barring unforeseen regulatory obstacles, the turbines could be spinning by 2011.