The amount of lead particulates in air has decreased significantly as the U.S. began adopting the use of unleaded gasoline and lead limits in the 1970s. Yet, because of the serious health hazards even very small amounts of lead pose to children, some experts believe no amount of lead in our environment is safe. Last year the EPA lowered the allowable lead level in the air by a factor of ten and some have called for an even lower limit. A recent study suggests that to do this one must not overlook the source of lead contamination beneath our feet. The soil serves as a reservoir for lead from the days of leaded gasoline and unregulated manufacturing and may determine a lower limit on the amount of airborne lead.
Approximately 1,700 scientists visit SSRL annually to conduct experiments in broad disciplines including life sciences, materials, environmental science, and accelerator physics. Science highlights featured here and in our monthly newsletter, Headlines, increase the visibility of user science as well as the important contribution of SSRL in facilitating basic and applied scientific research. Many of these scientific highlights have been included in reports to funding agencies and have been picked up by other media. Users are strongly encouraged to contact us when exciting results are about to be published. We can work with users and the SLAC Office of Communication to develop the story and to communicate user research findings to a much broader audience. Visit SSRL Publications for a list of the hundreds of SSRL-related scientific papers published annually. Contact us to add your most recent publications to this collection.
May 2009
In a similar way to your old pick-up truck rusting in the driveway, your body experiences a continuous battle against the elements. A constant barrage of oxidative stress attacks your cells and their constituent parts, including proteins. Like rust-proof paint on your vehicle, you have defense mechanisms that seek to prevent damage before it starts. But also like your trusty truck, once a weakness in the armor presents itself, it can spread rapidly — and often unnoticed — until you suddenly discover significant damage. Numerous diseases, as well as aging itself, are linked to uncontrolled oxidative processes that lead to irreversible damage and ultimately death. Understanding these oxidative processes may lead toward stopping and possibly even reversing damage.
X-ray Absorption Spectroscopy
BL6-2
May 2009
The tips of crab pincers are made of a very hard material, allowing the crab to fight and forage for food without wearing down their tools. Made mostly of proteins, the tip is known to be bromine-rich instead of calcium-rich, but the biochemical structure and mechanical properties were mostly unknown. Understanding this hard material made by crabs may lead to development of materials made by humans for use in a variety of purposes that require a small, fracture-resistant tool.
BL9-3
May 2009
Metals such as iron, copper, and zinc are critical for brain function, where they serve various roles, such as enzyme cofactors or neurotransmitters. Because the metal atoms can be reactive and cause cell damage, their locations and concentrations are tightly controlled. This control can be lost in some neurodegenerative diseases. Diseases like Alzheimer's dementia and Parkinson's disease are either caused by or lead to increased metal in areas of the brain, while others, like Menkes disease, are characterized by decreased concentrations of metals.
BL10-2
April 2009
Medications can be rendered ineffective through cells developing multidrug resistance. This is the case in many forms of cancer cells that fail to respond to chemotherapy. The ability of these cells to avoid the effects of drugs can be due to the actions of P-glycoprotein (P-gp). This protein sits in the membranes of cells and acts like a pump. It ushers a wide range of potentially harmful molecules from inside the membrane to outside the cell. Unfortunately, it can also mediate the removal of life-saving medications.
Macromolecular Crystallography
BL9-2, BL11-1
April 2009
Before DNA is made, the subunits composing DNA must be made. The essential process of making one of these subunits, thymidine monophosphate (TMP), was thought to be similar for most living things, but scientists recently discovered that some bacteria and viruses use a different type of enzyme to perform this reaction. The discovery might result in new antibiotics that would be effective against human pathogens, but not affect human cells.
Macromolecular Crystallography
BL9-2
April 2009
Nitric oxide (NO) is one of very few gaseous signaling molecules in humans. NO causes smooth muscles to relax and blood vessels to open. Its deficiency leads to disorders such as hypertension and impotence, but too much NO can lead to rheumatoid arthritis, stroke, cancer, and other diseases. Three distinct but related enzymes (called nitric oxide synthases) make NO from an arginine molecule. One of the nitric oxide synthases, iNOS, creates localized, high concentrations of NO as part of the body's immune response. Because it is this elevated activity of iNOS that can cause disease, scientists would like to specifically inhibit the action of iNOS without interfering with the activity of the other two enzymes, eNOS and nNOS. Since the three enzymes have identical active sites (i.e. where NO is made), finding an inhibitor that will bind in this site for iNOS but not eNOS nor nNOS has proved challenging.
Macromolecular Crystallography
BL7-1, BL9-1, BL9-2
March 2009
One of the strangest consequences of quantum mechanics is the seemingly instantaneous communication of subatomic particles over long distances. Known as quantum entanglement, pairs or groups of particles can become linked so that any changes made to one will cause the others to respond quicker than the time it takes for light to travel between them.
Angle-resolved photoelectron spectroscopy
BL5-4
March 2009
Scientists have recently identified a family of human antibodies that can take out an unprecedented number of different types of flu viruses, including H5N1 'bird flu' and the 1918 H1N1 'Spanish flu', which killed millions around the world during World War I, as well as seasonal flu. Using SSRL's Beam Line 9-2, Dr. Robert Liddington from the Burnham Institute for Medical Research led a team of scientists that determined the crystal structure of one such antibody, F10, in complex with the hemagglutinin H5 to unveil the molecular mechanism of virus neutralization. Results were published online 22 February 2009 in the journal Nature Structural and Molecular Biology.
Macromolecular Crystallography
BL9-2
February 2009
Organomercury is a well-known poison, and the potential for exposure worries many communities worldwide. Developing embryos are especially susceptible to mercury poisoning, which can result in serious birth defects. Despite the awareness of mercury's adverse health affects, little is known about the mechanisms for mercury toxicity.
BL2-3, BL9-3
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