NIST Tech Beat - February 10, 2009

In an unusual intersection of materials science and anthropology, researchers from the National Institute of Standards and Technology (NIST) and The George Washington University (GWU) have applied materials-science-based mathematical models to help shed light on the dietary habits of some of mankind’s prehistoric relatives. Their work forms part of a newly published, multidisciplinary analysis* of the early hominid Australopithecus africanus by anthropologists at the State University of New York at Albany and elsewhere.

In the new study, Albany researcher David Strait and his colleagues** applied finite element analysis—an engineer’s modeling tool that employs an intricate geometric mesh to calculate the stresses and strains at play in complex shapes—to the teeth and jaws of A. africanus, an African hominid that lived 2 to 3 million years ago. Their goal was to determine just how, and with how much force, the animal chomped and chewed its food. Such analyses are of great importance to anthropologists. Teeth are the hardest parts of the body, and so are the parts most likely to be found after millions of years. Careful examination of subtle features of teeth and jaws can reveal what an animal could eat, which implies what it did eat, which implies a host of things about its environment, habits and survival strategies.

A. africanus presented a puzzle. Classical analysis of the skull—large molars and premolars with thick enamel, thick heavy jawbones, strong chewing muscles as evidenced by their anchor points on the bone—pointed to a diet of small, hard seeds. The finite-element analysis threw a spanner in the works. It suggested that A. africanus’s facial and jaw anatomy was optimized to handle stress on the premolars, teeth located farther forward in the mouth and most useful for chewing larger hard objects. But recent studies had shown that the teeth lacked the microscopic wear patterns characteristic of chewing hard objects, a contradiction.

Here, work by NIST researcher Brian Lawn and a group at GWU headed by Peter Lucas came in handy. Driven by an interest in tooth restoration materials, they had been studying teeth using fracture mechanics, a field that considers how materials fail under excessive loads. “Our analytical approach produces equations that predict how each mode of damage will occur under different conditions and this enables us to determine trends for different tooth sizes, different food sizes, different food hardness and so on,” explained Lawn. “What they show is that, under some conditions, teeth will actually fracture before they wear.” This explained the absence of microwear patterns in the teeth, which would normally not be used for chewing small hard seeds. “A lot of people have thought the most important part of the survival of the tooth is wear, but it’s now becoming evident that the fracture properties are also very important because there’s a limit to the force that you can apply. Wear is important, but when you start to bite on harder, larger objects, fracture becomes more important,” Lawn said.

“This is a neat example of how really basic materials science—fracture mechanics—has important implications for biological sciences and anthropology,” Strait observed. In the bigger picture, said Strait, the new understanding about A. africanus’s diet may help to explain its successful adaptation to changing climates. A large hard nut that had to be cracked with the premolars may not have been a preferred meal, but it could be something to fall back on when other foods were scarce.

* D.S. Strait, G.W. Weber, S. Neubauer, J. Chalk, B.G. Richmond, P.W. Lucas, M.A. Spencer, C. Schrein, P.C. Dechow, C.F. Ross, I.R. Grosse, B.W. Wright, P. Constantino, B.A. Wood, B. Lawn, Q. Wang, D.E. Slice, C. Byron and A.L. Smith. The feeding biomechanics and dietary ecology of Australopithecus africanus. Proceedings of the National Academy of Sciences. Published online Feb. 2, 2009, doi:10.1073/pnas.0808730106

** Contributors to the complex effort included researchers from the State University of New York at Albany, the University of Vienna, the Max-Planck-Institute for Evolutionary Anthropology, the Smithsonian Institution, Arizona State University, Baylor College of Dentistry, the University of Chicago, the University of Massachusetts, the Kansas City University of Medicine and Biosciences, the Mercer University School of Medicine and Mercer University as well as NIST and The George Washington University.

The National Institute of Standards and Technology (NIST) has developed a new certified reference material that can be an important quality assurance tool for measuring the amounts of vitamins, carotenoids, and trace elements in dietary supplements. The new Standard Reference Material (SRM) 3280 for multivitamin/multimineral tablets was created in collaboration with the Office of Dietary Supplements (ODS) at the National Institutes of Health (NIH).

Demand from a growing number of Americans concerned that they are not getting all the prescribed nutrients from their food has created a multibillion-dollar dietary supplement industry. Although manufacturers have their own testing methods and materials to ensure that their products contain the nutrients in the amounts listed on their labels, they have had no definitive, independently certified standard with which to verify their testing methods and calibrate their equipment. The new reference standard will help fill that gap.

A manufacturer of multivitamin/multimineral tablets prepared the source material for SRM 3280 as a non-commercial batch of tablets according to their normal procedures. NIST scientists tested and certified the concentrations of 24 elements and 17 vitamins and carotenoid compounds in the tablets.

“We are not saying what a product should contain, but what it does contain,” Sharpless said. “Our SRMs are intended for analytical chemists to use to make sure their methods are working properly, not a benchmark for what a good product should be.”

SRM 3280 is part of a larger ongoing effort the NIST group has undertaken to develop reference materials for fatty acids, caffeine, and a whole host of other dietary supplements including ginkgo, saw palmetto, and bitter orange, and others as they appear on store shelves.

The SRM will also be used to support the efforts of the ODS and the U.S. Department of Agriculture in developing accurate data for the Dietary Supplement Ingredient Database (DSID). Researchers in the academic community will also be able to use the SRM to benchmark their assays for vitamins and minerals just as other SRMs are used to standardize serum cholesterol measurements.

The bacterium behind one of mankind’s deadliest scourges, tuberculosis, is helping researchers at the National Institute of Standards and Technology (NIST) and Brookhaven National Laboratory (BNL) move closer to answering the decades-old question of what controls the switching on and off of genes that carry out all of life’s functions.

In a new paper* the NIST/BNL team reported that it had defined—for the first time—the structure of a “metabolic switch” in its “off” state. The switch, which is found inside most types of bacteria, is in a protein called the cyclic AMP (cAMP) receptor (CRP). CRP is the binding site for cAMP, a small molecule that, once attached, serves as the signal to throw the switch. This “on” state of CRP then turns on the genes that help a microbe survive in a human host.

The researchers hope that once the switching mechanism is understood the data can be used to develop new methods for preventing tuberculosis and other pathogenic bacterial diseases. Additionally, they believe that learning how this specific protein switch works may provide insight into how genes in general are regulated.

The biochemical puzzle surrounding the CRP switch is the mechanism by which the protein binds cAMP at one end and attaches to—and activates—a gene at the other end. Believing that the protein somehow changes its overall shape after binding cAMP, researchers set out 25 years ago to study the structure of CRP in both its active state (with cAMP bound to it) and inactive state (without bound cAMP) to document where the morphing occurs.

Unfortunately, the task proved to be extremely difficult. Protein structures are worked out using a technique called X-ray diffraction, but it requires the protein to be crystallized, and proteins often are very hard to crystallize. Using CRP from the bacterium Escherichia coli, researchers were able to crystallize the protein in its active (“on”) state, but the structure of the inactive (“off”) E. coli CRP eluded them as attempts to crystallize it repeatedly failed. With only the structure of the “on” state defined, the genetic switching mechanism remained a mystery.

The breakthrough was achieved when NIST biochemist Travis Gallagher and colleagues substituted the CRP from Mycobacterium tuberculosis for the E. coli protein.

The team’s initial success—obtaining crystals of CRP in the “off” state—was dramatic given that no one had accomplished the feat in nearly three decades of trying with E. coli. But the real excitement came when the crystals were examined with X-ray diffraction.

“Although the M. tuberculosis protein in the ‘off’ state consists of two subunits that are genetically identical, we were surprised to see that the subunits were not structurally symmetrical as well,” Gallagher says. “In most two-subunit proteins, each subunit has the same conformation as the other.”

Gallagher says that the NIST/BNL team theorizes that it is the asymmetry in the absence of cAMP that prevents the protein from attaching to DNA. This, in turn, keeps CRP from activating genes when they are not needed.

The team’s next step is to crystallize M. tuberculosis CRP in the active state and define its structure, so that the both states of the protein from the same organism will be known.

* D.T. Gallagher, N. Smith, S-K Kim, H. Robinson and P.T. Reddy. Profound asymmetry in the structure of the cAMP-free cAMP receptor protein (CRP) from Mycobacterium tuberculosis. Journal of Biological Chemistry (published online Feb 4, 2009).

Minutes after a two-story townhouse caught fire on Feb. 5, engines and crews raced to the townhouse to extinguish the fire and search for victims. No one was injured, however, because this was one of many fire experiments performed this winter by researchers from the National Institute of Standards and Technology (NIST) and other organizations. The tests with real fires and real firefighters are part of a landmark study examining the effect of firefighter crew sizes and equipment arrival times on fire growth rates and an occupant’s ability to survive a building fire.

One day these experiments may help cut the number of people injured or killed in fires, as well as reduce property damage, by helping governments make more informed decisions that match firefighting resources with risks to the public and firefighters in their communities.

Fire is a costly problem. According to the National Fire Protection Association, in 2007 there were 530,500 structure fires that killed 3,000 civilians and injured more than 15,000 while causing $10.6 billion in property damage. About 100 firefighters die in the United States each year—9/11 being the exception. Many more are injured.

The study focuses on the effects of crew size (two, three, four and five persons per fire engine) and apparatus arrival time (all engines/trucks arrive close together or arrive at longer intervals) on the fire conditions within one 2,000-square-foot two-story townhome specially built to survive the many fires required for these experiments. This “burn house” was instrumented with state-of-the-art equipment to monitor the interior temperatures and toxic gas buildup within the structure. In addition, researchers monitored 22 different firefighting tasks at the site.

Each day over the course of two weeks, about 50 firefighters from Montgomery County, Md., and nearby Fairfax County, Va., participated in the experiments held at the Montgomery County Fire & Rescue Training Center in Rockville, Md.

“Currently local governments rely on trial and error or a qualitative basis to allocate fire-fighting resources,” explains NIST researcher Jason Averill. “When this study is complete, there will objective data on which to base these important decisions.” The study is due to be completed in Fall 2009.

The research is being conducted by a broad coalition in the firefighting community, including national labor and management organizations, and funded by the U.S. Department of Homeland Security, Federal Emergency Management Agency’s Assistance to Firefighters Grant Program. Researchers in NIST’s Building and Fire Research Laboratory planned these experiments with fire researchers from the International Association of Fire Fighters and Worcester Polytechnic Institute.

If the funding is continued, researchers plan to develop and validate a computer model that will allow local government decision makers to conduct “what if” analyses to help them make informed choices about managing resources for public and firefighter safety.

The National Institute of Standards and Technology (NIST) has issued for public comment its first major update of Special Publication 800-53, the catalog of security controls and technical guidelines that information technology professionals use to select appropriate safeguards and countermeasures for protecting federal information and information systems. SP 800-53, Revision 3, Recommended Security Controls for Federal Information Systems and Organizations, is one of the principal security publications in the suite of security standards and guidelines published by NIST in response to the Federal Information Security Management Act (FISMA) of 2002.

Ron Ross, FISMA Implementation Project leader, says, “We have received excellent feedback from our customers during the past three years and have taken this opportunity to provide significant improvements to the security control catalog. We also continue to work closely with the Department of Defense and the Office of the Director of National Intelligence under the auspices of the Committee on National Security Systems on the harmonization of security control specifications across the federal government.”

SP 800-53 Revision 3 incorporates lessons learned since the original publication to update many of the current security controls, adds new security controls and control enhancements to cover advanced cyber threats, and provides a new family of controls to address organization-wide security programs. The revision introduces the concept of an information security program plan, a vehicle to capture organization-wide security program management requirements—such as capital planning and budgeting, enterprise architectures, and risk management. The revision also eliminates redundant or obsolete controls. In addition, the growing sophistication of cyber attacks necessitated specific changes to the allocation of security controls and control enhancements to the minimum baseline controls recommended by NIST.

In addition to the above modifications, Revision 3 incorporates an overview of a revised, simplified six-step risk management framework, provides additional guidance on managing common controls within organizations and adds security controls for supply chain threats. It also introduces a strategy for harmonizing the FISMA security standards and guidelines with international security standards including an updated mapping table for security controls for organizations wanting to comply with both FISMA and the International Standards Organization 27001 security standard.

Representatives from business and government agencies concerned with intellectual property rights, particularly those concerning electronic devices, will gather for a special workshop at the National Institute of Standards and Technology (NIST) to focus on fighting the worldwide problem of counterfeit goods. The Product Authentication Management Workshop will be held on Feb. 17 and 18 at NIST’s main laboratories in Gaithersburg, Md.

Presentations by experts from academia, industry and government will address the root causes of counterfeiting, information management strategies for mitigating and pre-empting counterfeits, and the standards that are being developed to combat the problem. The program will include a presentation by Kevin Kurland, director of the Department of Commerce’s Bureau of Industry Security, Office of Technology Evaluation, concerning the results of a recent extensive survey regarding the incidence of electronic products in the marketplace.

The workshop is being sponsored by NIST and SEMI (Semiconductor Equipment and Materials International).

Media representatives wishing to attend the workshop should contact Chad Boutin at (301) 975-4261, or email boutin@nist.gov.

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Editor: Michael Baum

Date created: February 10, 2009
Date updated: February 11, 2009
Contact: inquiries@nist.gov