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Public release date: 20-Oct-2009ARTICLE HIGHLIGHTS
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"Superspreaders" may trigger hospital outbreaks
Health-care workers (HCWs) who roam from patient to patient in a hospital ward may play a disproportionate role in spreading pathogens. Laura Temime and colleagues used a mathematical model of a hypothetical intensive care unit to determine how easily common hospital-based infections, including antibiotic-resistant enterococci or Staphylococcus aureus, spread. The researchers separated HCWs into three groups: a "nurse-like" group, which made frequent visits to a small number of assigned patients; a "physician-like" group, which made infrequent visits to a larger number of patients; and a "peripatetic" group, which, like a physical therapist or radiologist, visited all patients daily. The authors found that infection outbreaks increased when HCWs failed to follow standard hand washing procedures. However, the infection rates increased by up to three times more when a peripatetic HCW failed to wash his or her hands compared with a HCW from the other groups. The infection rate from a single peripatetic HCW failing to wash their hands was equivalent to the infection rate when 23 percent of all HCWs on the ward failed to hand wash. The researchers suggest that the unusual profile of peripatetic HCWs makes them potential "superspreaders," indicating that hygiene measures in hospitals may need to be done individually rather than globally.
Article #09-00974: "Peripatetic health-care workers as potential superspreaders: An agent-based modeling study," by Laura Temime, Lulla Opatowski, Yohan Pannet, Christian Brun-Buisson, Pierre Yves Boëlle, and Didier Guillemot
MEDIA CONTACT: Laura Temime, Conservatoire des Arts et Métiers, Paris, FRANCE; tel: +33-1-53-01-80-11; e-mail: laura.temime@cnam.fr
Sensitive test for prostate cancer recurrence
Researchers have developed a test that can spot the recurrence of prostate cancer earlier than conventional tests, which could allow physicians to identify warning signs that the disease may return following prostate surgery. Chad Mirkin and colleagues used gold nanoparticles to detect prostate specific antigen (PSA), a marker of prostate cancer found in the blood, in 18 men. The researchers found that the test is nearly 300 times more sensitive than current commercially available assays. With their measurement technique, low levels of PSA, which would likely have been missed using existing measures, could be detected in samples from every patient following surgery, according to the authors. In some samples, the authors associated a rise in the patient's PSA levels and a recurrence of the cancer, whereas in others, low levels of PSA were connected with the cancer's non-recurrence. The researchers suggest that their test may be able to help physicians determine which prostate cancer patients are likely to stay cancer-free after surgery and which are relapsing. The method may also help monitor the effectiveness of post-surgery therapies such as chemo- or radiation therapy, according to the authors.
Article #09-04719: "The nanoparticle-based bio-barcode assay redefines 'undetectable' PSA and biochemical recurrence following radical prostatectomy," by C. Shad Thaxton, Robert Elghanian, Audrey D. Thomas, Savka I. Stoeva, Jae-Seung Lee, Norm D. Smith, Anthony J. Schaeffer, Helmut Klocker, Wolfgang Horninger, Georg Bartsch, and Chad A. Mirkin
CONFLICT OF INTEREST REPORTED: Chad A. Mirkin, C. Shad Thaxton, and Norm D. Smith are shareholders in Nanosphere, Inc., the company which licensed the bio-barcode assay from Northwestern University.
MEDIA CONTACT: Chad Mirkin, Department of Chemistry, Northwestern University, Evanston, IL; tel: 847-491-2907; e-mail: chadnano@northwestern.edu
On target to prevent cocaine relapse
A compound developed to have a shorter duration of activity than existing chemical treatments for drug abuse may help prevent cocaine relapse caused by stress. Current medications that target the brain's kappa opioid receptors (KOR) can last for weeks, during which time they prevent classic opioid effects and elicit antidepressant and antianxiety activity. However, existing KOR antagonists are thought to have several drawbacks, including neurochemical modulation, which makes the long-term activity of the compounds potentially detrimental in patients. To produce antagonists with a shorter duration of activity, Jane Aldrich and colleagues looked to peptides, which are quickly chewed up by enzymes in the body. The researchers added a chemical ring to a KOR-selective peptide to keep the peptide from being inactivated too quickly. The resulting compound, zyklophin, can cross the blood-brain barrier, block KOR, and was shown to reduce stress-induced cocaine-seeking behavior in mice. With activity lasting less than 12 hours and the ability to be administered by subcutaneous injection, zyklophin shows promise as a potential therapeutic KOR antagonist that could potentially be used to help people resist relapse to cocaine abuse.
ARTICLE #09-10180 "Zyklophin, a systemically active selective kappa opioid receptor peptide antagonist with short duration of action," by Jane V. Aldrich, Kshitij A. Patkar, and Jay P. McLaughlin
CONFLICT OF INTEREST REPORTED: The authors have filed a U.S. patent application on using zyklophin entitled "Method for Treating and/or Preventing Drug Seeking Behavior."
MEDIA CONTACT: Jane Aldrich, Department of Medicinal Chemistry, University of Kansas, Lawrence, KS; tel: 785-864-2287 (day), 785-764-0016 (evening); e-mail: jaldrich@ku.edu
MEDIA CONTACT: Jay McLaughlin, Torrey Pines Institute for Molecular Studies, Port St. Lucie, FL; tel: 772-345-4715 (day), 772-812-7448 (evening); e-mail: jmclaughlin@tpims.org
Stretched DNA melts apart
Researchers have discovered that double-stranded DNA, when stretched beyond its limits, melts apart as if under high temperatures. These results could provide a basis for the understanding of DNA-protein interactions and the thermodynamics of DNA, which are crucial to a number of cellular processes including cell division and transcription. Erwin Peterman and colleagues investigated the elasticity of DNA by "overstretching" the nucleic acid spiral, attaching one end of each molecular strand to a solid microsphere. The researchers indicate that the stretching was likely initiated from adenine and thymine-rich regions, and that the double-stranded DNA required a minimal amount of force to begin coming apart. This overstretching initiated with fraying at the extremities and moved consistently in both directions until the two helically wound DNA strands pulled apart to form single strands. When both strands of the DNA were fixed to a solid substrate, however, the force required to melt the strands nearly doubled, according to the authors.
Article #09-04322: "Unraveling the structure of DNA during overstretching using multicolor, single-molecule fluorescence imaging," by Joost van Mameren, Peter Gross, Geraldine Farge, Pleuni Hooijman, Mauro Modesti, Maria Falkenberg, Gijs J. L. Wuite, and Erwin J. G. Peterman
MEDIA CONTACT: Erwin Peterman, Department of Physics and Astronomy, VU University Amsterdam, Amsterdam, NETHERLANDS; tel: +31-20-598-7576 (day), +31-65-386-0894 (evening); e-mail: erwinp@nat.vu.nl
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Nitric oxide key to survival of "world's toughest" bacterium
Nitric oxide is likely the key to the bacterium Deinococcus radiodurans' ability to withstand doses of radiation that would kill larger organisms. The hardy prokaryote is being exploited for remediation of radioactive waste sites and some Deinococcus species are found in canned food products. The organism has been called the "world's toughest bacterium" because it can withstand extreme temperatures, severe dehydration, and lethal doses of radiation. Brian Crane and colleagues investigated the bacterium's radiation-survival ability and discovered that ultraviolet light exposure increased Deinococcus' production of nitric oxide synthase, the enzyme responsible for creating nitric oxide. In animals, nitric oxide has been shown to play a role in a number of biological processes, including protection from pathogens, regulation of vascular tension, hormone release, and neuronal signaling. The authors used a genetically modified version of D. radiodurans with the synthase enzyme removed and found that, although the bacteria survived other stressors, including exposure to free radicals, they fared poorly after radiation exposure.
Article #09-07262: "Endogenous nitric oxide regulates the recovery of the radiation-resistant bacterium D. radiodurans from exposure to UV light," Bhumit A. Patel, Magali Moreau, Joanne Widom, Huan Chen, Longfei Yin, Yuejin Hua, and Brian R. Crane
MEDIA CONTACT: Brian Crane, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY; tel: 607-254-8634; e-mail: bc69@cornell.edu
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Greenland ice core offers paleo-record contrast
Evidence from well-preserved, organic-rich interglacial lake sediments found in Greenland may provide a paleo-perspective for lake sediment records from the Canadian Arctic.
Article #09-07094: "Recent changes in a remote Arctic lake are unique within the past 200,000 years," by Yarrow Axford, Jason P. Briner, Colin A. Cooke, Donna R. Francis, Neal Michelutti, Gifford H. Miller, John P. Smol, Elizabeth K. Thomas, Cheryl R. Wilson, and Alexander P. Wolfe
MEDIA CONTACT: Yarrow Axford, Institute of Arctic and Alpine Research (INSTAAR), University of Colorado, Boulder, CO; tel: 716-380-5027; e-mail: axford@colorado.edu
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