Worried about a heart attack? You should exercise, eat right and keep your teeth clean, according to a team from the University of Minnesota. They reckon that the bacteria found in plaque can cause blood platelets to clump up - the first stage toward a blood clot that could cause a heart attack or stroke. Gum disease then offers those bacteria a good route into the bloodstream; and several researchers have reported recently finding bacteria in the atherosclerotic plaque that clogs diseased coronary arteries.

Dr Mark Herzberg of the University of Minnesota, found that germs taken from dirty and diseased gums and infused into rabbits led to abnormal electrocardiograms and faster heart and breathing rates. Using a different bacterium did not have these effects.

Why? Some bacteria found in plaque and gum disease produce a protein called platelet aggregation associated protein or PAAP. This could be the key to the problem, Dr Herzberg said.

Spun but not shaken: that was John Glenn, soon to be the oldest astronaut, after he had a session in the training centrifuge at Brooks Air Force Base in Florida last Thursday. The whirling arm, intended to simulate the intense gravitational experience of a Space Shuttle launch, generated forces of up to 3g (three times the force of gravity). Officials had an ambulance standing by, "just to make sure", though they also insisted that they were "not at all worried" that the former and future astronaut would have any problems.

Glenn, who is now a senator, was the centrifuge's oldest rider: the former record-holder was aged 64. Taking a ride on the machine is a training requirement for all first-time space shuttle fliers, to acquaint them with the rigors of launch.

Building nanometre-scale machines could become easier using a technique devised by Israeli scientists, who have used DNA to grow wires just a few nanometres wide between two electrodes. Each electrode had a DNA "anchor" at the end: a "bridge" of DNA which would attach to those anchors was then added, and selected those electrodes to connect itself.

After that the researchers, at the Technion-Israel Institute of Technology, Haifa, added positively-charged silver ions, which attached to the negatively charged DNA. According to their report in Nature, the ions were then chemically turned into silver atoms, leaving a silver bridge just 12 micrometres long. It's a technique which could be used to build the chips of the future: "Self-assembly is well-developed in nature," said one researcher. "The whole toolbox is there."