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Zebrafish Provide A Model For Cancerous Melanoma In Humans
In a new study published in Disease Models & Mechanisms, scientists use the zebrafish to gain insight into the influence of known cancer genes on the development and progression of melanoma, an aggressive form of human skin cancer with limited treatment options.
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Washington, D.C., Officials Expand STI Testing Program To All Public High Schools
Washington, D.C., officials are planning to make testing for sexually transmitted infections available at all public high schools in the coming school year, adding D.C. to a growing list of cities that test students for STIs, the Washington Post reports. All 50 states and the district allow minors older than age 12 to be tested for STIs without parental consent.The new program requires all students to attend a lecture about STIs, after which they are escorted into restroom areas in groups of 15 to 20. They are then given paper bags with urine collection cups and go into the stalls, at which point they can decide whether to provide a sample. All students return the paper bags, regardless of whether they provided samples. Students give a password and can call a week later to receive their confidential results and, if necessary, treatment at the school or an STI clinic, which is paid for by the city. The district first offered the program two years ago at two charter schools, and eight high schools were included during the past school year.A 2007 study by the D.C. public school system found that 60% of high school students and 30% of middle school students reported having sex. According to the study, 20% of high school students reported having sex with four or more partners and 12% of middle school students reported having three or more partners.According to the D.C. Department of Health, the program at eight high schools last year found that 13% of 3,000 students tested positive for an STI, most commonly chlamydia or gonorrhea. Fifty percent of the chlamydia and gonorrhea cases in the district are among teenagers.According to the D.C. Appleseed Center for Law and Justice, the new program is an important step toward curbing the district"s HIV/AIDS rate, which is among the highest in the U.S. Walter Smith, executive director of D.C. Appleseed, said, "If 13% of these students are testing positive for [STIs], those same kids could get HIV," adding, "A lot needs to be done to get the message out to the schools, ... and this very high [STI] rate is an indication that what we"ve been doing is not effective" (Fears/Hernandez, Washington Post, 8/5).
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Health Undermined By Divorce In Ways Remarriage Doesn't Heal
Divorce and widowhood have a lingering, detrimental impact on health, even after a person remarries, research at the University of Chicago and Johns Hopkins University shows.
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Nonstick And Laser-safe Gold Aids Laser Trapping Of Biomolecules

Biophysicists long for an ideal material - something more structured and less sticky than a standard glass surface - to anchor and position individual biomolecules. Gold is an alluring possibility, with its simple chemistry and the ease with which it can be patterned. Unfortunately, gold also tends to be sticky and can be melted by lasers. Now, biophysicists at JILA have made gold more precious than ever - at least as a research tool - by creating nonstick gold surfaces and laser-safe gold nanoposts, a potential boon to laser trapping of biomolecules. JILA is a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder. JILA"s successful use of gold in optical-trapping experiments, reported in Nano Letters,* could lead to a 10-fold increase in numbers of single molecules studied in certain assays, from roughly five to 50 per day, according to group leader Tom Perkins of NIST. The ability to carry out more experiments with greater precision will lead to new insights, such as uncovering diversity in seemingly identical molecules, and enhance NIST"s ability to carry out mission work, such as reproducing and verifying piconewton-scale force measurements using DNA, Perkins says. (A one-kilogram mass on the Earth"s surface exerts a force of roughly 10 newtons. A piconewton is 0.000 000 000 001 newtons. See "JILA Finds Flaw in Model Describing DNA Elasticity" NIST Tech Beat, Sept. 13, 2007.) Perkins and other biophysicists use laser beams to precisely manipulate, track and measure molecules like DNA, which typically have one end bonded to a surface and the other end attached to a micron-sized bead that acts as a "handle" for the laser. Until now, creating the platform for such experiments has generally involved nonspecifically absorbing fragile molecules onto a sticky glass surface, producing random spacing and sometimes destroying biological activity. "It"s like dropping a car onto a road from 100 feet up and hoping it will land tires down. If the molecule lands in the wrong orientation, it won"t be active or, worse, it will only partially work," Perkins says. Ideally, scientists want to attach biomolecules in an optimal pattern on an otherwise nonstick surface. Gold posts are easy to lay down in desired patterns at the nanometer scale. Perkins" group attached the DNA to the gold with sulfur-based chemical units called thiols (widely used in nanotechnology), an approach that is mechanically stronger than the protein-based bonding techniques typically used in biology. The JILA scientists used six thiol bonds instead of just one between the DNA and the gold posts. These bonds were mechanically strong enough to withstand high-force laser trapping and chemically robust enough to allow the JILA team to coat the unreacted gold on each nanopost with a polymer cushion, which eliminated undesired sticking. "Now you can anchor DNA to gold and keep the rest of the gold very nonstick," Perkins says. Moreover, the gold nanoposts were small enough - with diameters of 100 to 500 nanometers and a height of 20 nanometers - that the scientists could avoid hitting the posts directly with lasers. "Like oil and water, traditionally laser tweezers and gold don"t mix. By making very small islands of gold, we positioned individual molecules where we wanted them, and with a mechanical strength that enables more precise and additional types of studies," Perkins says. The research was supported by a W.M. Keck Grant in the RNA Sciences, the National Science Foundation, and NIST. * D.H. Paik, Y. Seol, W. Halsey and T.T. Perkins. Integrating a high-force optical trap with gold nanoposts and a robust gold-DNA bond. Nano Letters. Articles ASAP (As Soon As Publishable) Publication Date (Web): June 3, 2009 DOI: 10.1021/nl901404s. Laura Ost National Institute of Standards and Technology (NIST)


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