When bacteria, viruses or parasites attack, immune system cells unleash the soldiers. These "hot" protein compounds kill invaders – but also trigger inflammation, which, if unchecked, can destroy tissue, induce shock and kill the host. So immune system cells let loose another protein compound to cool down the immune response.

The body's spinal cord is like a super highway of nerves. When an injury occurs, the body's policing defenses put up a roadblock in the form of a scar to prevent further injury, but it stops all neural traffic from moving forward.

In a landmark study, biologists at Florida State University have uncovered a specific genetic and molecular mechanism that causes cell polarity -- the asymmetric shape or composition critical to a cell's proper functioning. Their findings in fruit fly eggs may help to clarify how muscular dystrophy and some cancers develop in humans.

The internal body clock, or circadian rhythm, seems to influence the timing of different types of stroke, suggests research published ahead of print in the Journal of Neurology Neurosurgery and Psychiatry.

An international, multi-institutional research consortium is seeking to discover how a few HIV-infected individuals are naturally able to suppress replication of the virus. The Elite Controller Collaborative Study (http://www.mgh.harvard.edu/aids/hiv_elite_controllers.asp), the first large-scale haplotype-mapping study in people infected with HIV, is searching for genetic factors that may explain these individuals' unique ability to control the virus without treatment, sometimes as long as 25 years after infection.

Since completing the sequencing of the chimpanzee genome last year, geneticists have spent many hours comparing human DNA sequences to those of our closest evolutionary relative, looking for the differences that distinguish the two species. Now a team of researchers has found the human DNA sequence with the most dramatically increased rate of change.

A genetic analysis of soil samples indicates that a group of microorganisms called crenarchaeota are the Earth's most abundant land-based creatures that oxidize ammonia, according to an international team of researchers from Norway, Germany, United Kingdom and the United States.