September 16, 2002

In This Issue:
	‘Double Knock-Out’ Pigs Score TKO for ATP Project
	Idaho Educator Learns ‘On the Job’ About Environmental Monitoring
	Study Finds NIST Gas Standards Yield Substantial Benefits
	NIST Gets the Drop on Fire Quenchers
	NIST Research Finds Waveguide Lasers Offer Advantages

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Genetics

‘Double Knock-Out’ Pigs Score TKO for ATP Project

On Aug. 22, 2002, researchers at PPL Therapeutics Inc. (Blacksburg, Va.) announced a significant milestone in the campaign to produce genetically altered pigs whose organs and tissues can be transplanted into humans with a significantly reduced probability of rejection. In a project co-sponsored by the National Institute of Standards and Technology (NIST) Advanced Technology Program (ATP), PPL scientists successfully cloned four piglets that have been genetically modified to “knock out” or silence both copies of a key gene tied to the acute rejection of pig organs by the human immune system.

Pigs long have been eyed as a possible source of transplant organs for humans. Their organs are approximately the same size as human equivalents and they have a similar physiology; indeed, pig heart valves treated to remove any actual pig cells have been used in humans for two decades. For many, the question is not academic—more than 85,000 patients on waiting lists for transplant organs spend billions of dollars annually on treatments that would be unnecessary with a suitable transplant. An estimated 16 people die each day in the United States for lack of suitable transplant organs.

Xenotransplants (the transplantation of an organ from an individual of one species into an individual of another species) of major organs are currently impossible. Unlike the vast majority of mammals, humans (and other primates) lack a particular sugar attached to the surface of cells, and the presence of this sugar on pig cells triggers an immediate, acute immune-system response by the human body that kills the transplanted tissue in a matter of minutes. Last year, PPL researchers successfully used genetic engineering techniques to “knock out” one copy of the gene responsible for the sugar complex in five piglets. However, every animal carries two copies of every gene.

Now, in a significant advance, the PPL research team has produced animals lacking both copies of the key gene, known as alpha 1,3 galactosyl transferase (GGTA1). Safe, practical xenotransplants face several other major technical and regulatory hurdles, but the PPL accomplishment is a critical step in the development of a technology that could revolutionize transplant therapies for a wide variety of diseases, including cell-level therapies for diabetes, Parkinson’s Disease and Alzheimer’s Disease.

The project at PPL Therapeutics is one of several ongoing ATP projects in xenotransplantation research, including additional work at PPL, and projects at Alexion Pharmaceuticals Inc. (Cheshire, Conn.) and Immerge BioTherapeutics Inc. (Charlestown, Mass.).

Details of the ATP project are available within the “Project Briefs” section of the ATP Web site, www.atp.nist.gov.

The PPL Therapeutics news release may be found at
www.ppl-therapeutics.com/news/news_1_content_51.asp.

Media Contact:
Michael Baum, (301) 975-2763

 

Physics

Idaho Educator Learns ‘On the Job’ About Environmental Monitoring

Linda Selvig, an earth science teacher at Centennial High School in Meridian, Idaho’s Joint School District No. 2, is now working at the National Institute of Standards and Technology (NIST) under the auspices of the Albert Einstein Distinguished Educator Fellowship Program. The program offers elementary and secondary science and mathematics teachers year-long fellowships to serve on Capitol Hill and in federal agencies. It is administered by the U.S. Department of Energy and the Triangle Coalition for Science and Technology Education.

Selvig, a resident of Boise, Idaho, and a past president of the National Earth Science Teachers Association, has a strong interest in issues involving radioactivity and the environment. Her classes over the years have included studies on how the environment can become contaminated with radioactivity and the potential paths by which that contamination might reach the public.

During her year at NIST, Selvig will work with the NIST Radiochemistry Intercomparison Program (NRIP). The NRIP is responsible for making precise measurements of low-level radioactivity in a variety of samples (water, soil, sediment, air filter, synthetic feces and synthetic urine) and then having university, federal, national, interest group and contract laboratories assess their measurement capabilities using the NIST values.

Selvig will learn how to prepare environmental test samples (primarily water) and take measurements; conduct statistical evaluations of the measurement data; and report on her findings. She also plans to tie in her interest in geology by working on the Radionuclide Speciation Project, where she will investigate the uptake of radioactive materials in the minerals found in soils and sediments.

Information about the Einstein Fellowships is available at www.triangle-coalition.org/ein.htm.

Media Contact:
Michael E. Newman, (301) 975-3025

 

Economics

Study Finds NIST Gas Standards Yield Substantial Benefits

Accurate, real-time monitoring of polluting gases emitted by electric utilities, automobiles and other sources depends heavily on equipment calibration standards made by or traceable to the National Institute of Standards and Technology (NIST). A new study now available from NIST, The Economic Impact of the Gas-Mixture NIST-Traceable Reference Materials Program (NIST Planning Report 02-4), found that the gas-mixture NIST-Traceable Reference Materials (NTRM) program—an innovative mechanism for meeting a high demand for standards—returns between $21 and $27 in benefits for every dollar spent, with substantial benefits extending into the future.

The NTRM program was created in the early 1990s by NIST, the U.S. Environmental Protection Agency (EPA), and specialty gas companies to increase the availability of NIST-certified reference materials needed to monitor compliance with environmental regulations. Most EPA regulations for stationary source, mobile source and ambient air monitoring require that measurements be traceable to NIST. Under the program, gas companies manufacture standards according to NIST’s technical specifications and submit these mixtures to NIST for certification. (NIST also produces a smaller number of its own gas-mixture Standard Reference Materials, the benefits of which were not evaluated in the study.)

In addition to greatly increasing the supply of gas-mixture standards, the NTRM program, after an initial start-up investment by NIST, minimizes on-going costs to taxpayers because it is now supported by industry fees. According to the study, benefits of the program include reduced measurement uncertainty, helping users of the reference materials to avoid some operations and maintenance costs and reducing credit expenditures in emissions trading (an innovative approach to environmental regulation that is generally believed to reduce total pollution-abatement costs). The program enables NIST to meet the needs of these impacted industries, while freeing up its resources to solve other critical standards issues.

Copies of NIST Planning Report 02-4 are accessible at www.nist.gov/director/prog-ofc/report02-4.pdf, or in printed format by sending a request to denise.herbert@nist.gov.

Media Contact:
Michael E. Nemwan, (301) 975-3025

 

Fire Research

NIST Gets the Drop on Fire Quenchers

The behavior of tiny droplets of new liquid fire suppressants may play a big role in fire-fighting effectiveness. The new suppressants are proposed to replace halon suppressants now being phased out because they cause damage to stratospheric ozone.

The effectiveness of a suppressant depends on many factors. Do the droplets evaporate quickly or cling to a hot surface? Do they spread, shrink, splash or levitate? Liquid droplet interactions with surfaces have been studied for more than 100 years, but the complicated fluid mechanics process is still not well understood. Moreover, few studies have addressed what happens to water droplets containing fire-suppressing additives.

National Institute of Standards and Technology (NIST) researchers are studying the collision dynamics of single droplets, about 2.7 millimeter (0.1 inch) in diameter, as they strike a heated stainless steel surface. In one set of experiments, the behavior of pure water was compared to that of a solution with salt-containing additives (30 percent sodium acetate trihydrate). The researchers recorded what happened to the droplets at different impact energies and at different surface temperatures using a high-speed digital camera.

Among the findings—for both water and additive-containing droplets—the disk-shaped liquid film formed on the surface after impact grew in diameter at higher impact velocity, possibly providing increased surface cooling. The presence of the additive influenced the collision dynamics greatly at low impact energy, but less so as the velocity increased. This suggests that for high-velocity impact, knowing the evolution of liquid film diameter for water impact may be sufficient to determine the amount of surface cooling. These findings are important in fire suppression because droplets impinging on surfaces from sprinklers and pressure nozzles are expected to have relatively higher impact energies.

For more information, contact Samuel Manzello, (301) 975-6891, samuel.manzello@nist.gov.

Media Contact:
Jan Kosko, (301) 975-2767

 

 

Optoelectronics

NIST Research Finds Waveguide Lasers Offer Advantages

Waveguide lasers will fill an important niche as optical sources in communication, RF photonics, and optical metrology, according to research recently completed at the National Institute of Standards and Technology (NIST) Optoelectronics Division. NIST and the Defense Department’s Defense Advanced Research Projects Agency funded the research.

Waveguide lasers are compact with low noise, relatively high output powers, and long upper-state lifetimes, allowing them to be easily integrated with optical-fiber-based systems. Although NIST scientists do not expect waveguide lasers to replace fiber and semiconductor lasers in communication applications, waveguide lasers provide a number of advantages over traditional laser sources.

For example, single-frequency waveguide lasers provide narrow linewidth and high-output power in a compact package, which makes them better suited than fiber lasers or extended-cavity semiconductor lasers for applications such as remote sensing, wavelength division multiplexing (WDM), all optical RF photonics, and mobile laser platforms.

Mode-locked waveguide lasers, used in high-data-rate communications and photonic A/D conversion, provide short pulses with low jitter and high-average power and avoid the effects of super-mode and pattern noise found in harmonically mode-locked fiber lasers. Also, mode-locked waveguide lasers operate at repetition rates unsuitable for mode-locked semiconductor lasers.

For more information on NIST research looking at the advantages of waveguide lasers, contact Bert Callicoatt,
(303) 497-5952, bertc@boulder.nist.gov.

Media Contact:
Fred McGehan, Boulder (303) 497-7000