Virologists at Duke University Medical Center have discovered that, under the right conditions, a common cold virus closely related to poliovirus can cause polio in mice, Science Daily said.
The researchers injected a cold virus called Coxsackievirus A21 into mice that were engineered to be susceptible to this particular virus. However, instead of developing a cold, the mice unexpectedly displayed paralytic symptoms characteristic of polio. The researchers determined that administering the virus directly into muscles, instead of the virus's normal home in the nasal cavity, was critical for development of polio.
The findings challenge traditional views as to what defines a poliovirus, said Matthias Gromeier, M.D., a Duke virologist and senior author of the study.
"In principle, Coxsackieviruses could cause polio in humans," said Gromeier. Results of the study will be published in the Sept. 6, 2004, issue of the Proceedings of the National Academy of Sciences.
Until now, it has been widely accepted that Coxsackievirus and poliovirus cause distinct illnesses because they bind to different docking sites, called receptors, on host cell surfaces.
Poliomyelitis has long been regarded as the signature of poliovirus, a virus that recognizes and binds to the CD155 receptor. However, the mice were genetically engineered to have only the Coxsackie A21 receptor, called ICAM-1, and they did not have the poliovirus receptor.
In studying the virus' action within infected mice, they found that the virus traveled from the calf muscle where it was injected to the central nervous system along "motor neuron axons.
Such axons extend from the central nervous system to muscles throughout the body and convey commands for muscle movement. The site in the muscle where axons physically attach is called a neuromuscular junction. These junctions likely served as the cold virus' portal of entry into the nervous system.

Theoretical physicists in Italy and France have discovered a new family of "magic" clusters using computer simulations. The clusters, which consist of a nickel or copper core surrounded by silver atoms, display high levels of structural, thermodynamic and electronic stability. The silver-nickel structures are also magnetic.
According to physicsweb.org, magnetic levitation occurs when the force on a diamagnetic object--an object that is slightly repelled by a magnet--is strong enough to balance the weight of the object.
In the past, physicists have levitated a wide range of diamagnetic objects, including frogs, with powerful magnets. Lyuksyutov and colleagues have now extended this approach to much smaller objects by developing micron-sized magnetic traps.
The new device consists of two permanent magnets, 250 microns high and 10 millimetres across, separated from each other by about 80 microns and mounted on a steel plate.
The device creates a region of low magnetic field (the trap) surrounded by a region of high magnetic field. Since the energy of a diamagnetic object is proportional to the magnetic field energy density, it is energetically more favorable for the object to stay in the low field region.
The force on the object is proportional to the gradient of the energy density, which is high because the energy density changes over very short distances.
Liquid droplets are injected into the device from an atomizer and observed with an optical microscope. The Texas physicists found they could move, rotate or even merge droplets by applying electric or magnetic fields, and that they were able to control the potential energy of a droplet on the sub-zeptojoule (10-21 J) scale.
The apparatus could be used to levitate droplets of almost any non-paramagnetic substance and provides a completely new path to making labs-on-a-chip.

The European Space Agency's chief scientist has said that there should be a Noah's Ark on the Moon, in case the Earth was destroyed by an asteroid or nuclear holocaust.
Speaking exclusively to BBC News at the British Association Science Festival, Dr Bernard Foing said that the ark should be a repository for the DNA of every single species of plant and animal.
Dr. Foing is head of Europe's Moon missions, so his thoughts on matters lunar should be taken seriously.
He is concerned that if the Earth were destroyed, there would be little or nothing left of the rich diversity of life on the planet.
His solution is to build a DNA library on the Moon.
For the time being though, Foing is awaiting the arrival of Europe's first probe to the Moon.
That mission is due to arrive ahead of schedule in November.
It is the first of what he hopes will be a fleet of robotic spacecraft sent to the Moon.
They would be used to build a lunar colony.

Nanoscopic dots of nickel that could be used to store terabytes of data in a computer chip just a few centimetres wide have been created by US researchers.
Each "nanodot" consists of a discrete ball of several hundred nickel atoms and can have one of two magnetic states. This allows them hold a single bit of information, as a "1" or a "0".
In a conventional computer hard drive, information is stored on a disk coated with a magnetic material, and bits must be far enough apart not to interfere with each other.
Nanodots should allow bits to be packed closer together as the dots are discrete units that are not structurally linked.
Ashutosh Tiwari and Jagdish Narayan at North Carolina State University have created nickel nanodots measuring about 5 nanometres in diameter--about 10 times smaller than those previously produced.
The researchers used a pulsed laser to heat nickel until it turned into plasma - an amorphous form of matter with positively and negatively charged atoms. In this form, the nickel rearranged itself on two different substrates - aluminium oxide and tin titanium nitrate - as uniform dots.
The dots arranged themselves at a density that would, theoretically, allow about five terabytes of data--five thousand gigabytes--to be packed into computer drive roughly the size of postage stamp. "Now the aim should be to integrate these nanodots with silicon chips," Tiwari told New Scientist.
But others remain more cautious about the potential of the technique.
Narayan concedes that several problems still need to be overcome.
The fabrication technique could perhaps be used in other ways. It was also possible to arrange the dots in three dimensions within a substrate.
The pair found the nanodots could be arranged in a uniform manner within the crystalline structure of tin titanium nitrate.
In theory, this could strengthen the crystal lattice of a molecule, perhaps leading to the development of novel, super-strong materials, Narayan says.

Swiss scientists say they have discovered a cure for hayfever by making hay that doesn't cause an allergic reaction, ananova.com said.
The new treatment was created after a growing number of horses were diagnosed as suffering from hayfever.
But the scientists say the specially treated hay is just as good for hayfever prone humans who have to work with horses and other animals.
The hayfever-free hay is being marketed by businessman Hans Fankhauser who says he cannot produce it quickly enough to meet demand.
The hay is specially treated to remove dust and pollen and stop hayfever, but keeps all the essential ingredients to meet the animals' dietary requirements.
Scientists are at a loss to explain the rise in the number of allergies among horses and cattle, although the growing use of eco hay that has mature plants of different types mixed into it has been blamed.
Fankhauser, who has his own farm, spent five years helping the scientists develop a suction system for cleaning cut grass.
Martin Schaudt, a member of Germany's equestrian team, insisted that his horse, Weltall, be fed exclusively on Fanag's hay during the Athens Olympics.
Weltall and his rider were part of the team that won gold for Germany in the dressage competition.