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American Chemical Society's Weekly PressPac

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IMAGE: Scientists report that mouth bacteria are responsible for creating the distinctive flavors of certain foods, including some fruits and vegetables. view more

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Here is the latest American Chemical Society (ACS) News Service Weekly PressPac with news from ACS' 36 peer-reviewed journals and Chemical & Engineering News.


New insights into thalidomide-birth defect episode
Molecular Pharmaceutics

Scientists in Germany have discovered why the medication thalidomide appeared safe in animal tests before going on the market 50 years ago, only to cause perhaps the most extensive outbreak of drug-induced birth defects in medical history. Their study is scheduled for the December 1 edition of ACS' Molecular Pharmaceutics, a bimonthly journal.

Jurgen Knobloch, Ulrich Ruther and colleagues note that more than 10,000 children were born with severe birth defects after drug regulators in Europe approved the medication for treating nausea and vomiting in pregnant women. The drug, never approved for that use in the United States, is available for certain conditions, including multiple myeloma and leprosy. The birth defects outbreak puzzled scientists because pre-marketing tests in lab mice and rats showed no sign of a birth defect risk.

The researchers point out that those animals proved to be resistant to thalidomide's adverse effects, and in the new study they describe discovery of the biochemical basis for that resistance. It involves a key difference between human embryonic cells and those of mice. They found in mice cells advanced antioxidant defenses compared to those in humans and other thalidomide-susceptible species. Therefore, thalidomide is not able to induce the generation of large quantities of damaging free radicals called superoxides in mouse embryonic cells as it does in human embryonic cells (where subsequent cell death is believed to be responsible for birth defects.) -- JS

"Thalidomide Resistance Is Based on the Capacity of the Glutathione-Dependent Antioxidant Defense"


Jurgen Knobloch, Ph.D.
University of Cologne
Medical Clinic III
Department of Pneumology
Cologne, Germany
Phone: 49-221-4784191
Fax: 49-221-87031


Chemical magic in the mouth
Journal of Agricultural and Food Chemistry

Scientists in Switzerland are reporting that bacteria in the human mouth play a role in creating the distinctive flavors of certain foods. They found that these bacteria actually produce food odors from odorless components of food, allowing people to fully savor fruits and vegetables. Their study is scheduled for the November 12 edition of the ACS bi-weekly Journal of Agricultural and Food Chemistry.

In the study, Christian Starkenmann and colleagues point out that some fruits and vegetables release characteristic odors only after being swallowed. While scientists have previously reported that volatile compounds produced from precursors found in these foods are responsible for this 'retroaromatic' effect, the details of this transformation were not understood.

To fill that knowledge gap, the scientists performed sensory tests on 30 trained panelists to evaluate the odor intensity of volatile compounds - known as thiols - that are released from odorless sulfur compounds found naturally in grapes, onions, and bell peppers. When given samples of the odorless compounds, it took participants 20 to 30 seconds to perceive the aroma of the thiols - and this perception persisted for three minutes. The researchers also determined that the odorless compounds are transformed into the thiols by anaerobic bacteria residing in the mouth - causing the characteristic 'retroaromatic' effect. "The mouth acts as a reactor, adding another dimension to odor perceptions," they explain. However, the authors conclude, it is saliva's ability to trap these free thiols that helps modulate the long-lasting flavors. -- KSD

"Olfactory Perception of Cysteine - S-Conjugates from Fruits and Vegetables"


Christian Starkenmann, Ph.D.
Corporate R&D Division
Firmenich SA
Geneva, Switzerland
Phone: +41 22 780 34 77
Fax: +41 22 780 33 34


"Liquid mirror" advance may lead to better eye exams, improved telescopes
Chemistry of Materials

Scientists in Canada are reporting progress toward a new type of "liquid mirror" -- mirrors made with highly reflective liquids -- whose shape can be changed to provide superior optical properties over conventional solid mirrors. The advance could lead to improved instruments for diagnosing eye disease, more powerful telescopes, and other applications, the researchers say. Their research will be described in the November 25 issue of ACS' Chemistry of Materials, a bi-weekly journal.

In the report, Anna Ritcey, Jean-Philippe Dery, and Ermanno Borra note that "liquid mirrors" are not new. Scientists have long recognized that these liquids could provide a low-cost, easy-to-use alternative to solid mirrors for a variety of optical applications while offering the potential for less image distortion. Researchers have recently developed liquid-mirror telescopes that use mercury as the reflective material. Mercury, however, is toxic and the shape of the surface can't be deformed or adjusted.

The scientists describe development of a new type of deformable "liquid mirror" composed of magnetic iron particles, ethylene glycol (a component of automotive antifreeze), and a coating of silver nanoparticles. These materials form a highly reflective mirror whose shape can be changed by adjusting the voltage applied to electromagnets placed below the liquid, allowing the user to fine-tune the mirror's optical properties. In lab studies, the new material showed better reflectivity and stability than current liquid-mirror materials, the scientists say. -- MTS

"Ethylene Glycol Based Ferrofluid for the Fabrication of Magnetically Deformable Liquid Mirrors"


Anna M. Ritcey, Ph.D.
Departemente de Chimie
Universite Laval
Quebec, Canada
Phone: 418-656-2368
Fax: 418-656-7916


A new way to remove unwanted heparin from blood

Scientists in Poland are reporting development of a potential new way to quickly remove the anticoagulant heparin from patients' blood in order to avoid unwanted side effects that can happen with the current use of that blood thinner. Their new polymer material will be described in the December 8 issue of ACS' Biomacromolecules, a monthly journal.

In the new study, Krzysztof Szczubialka and colleagues point out doctors often want to remove heparin from the blood of patients undergoing surgery or other procedures immediately after completing the procedure. Leaving the heparin alone could lead to unwanted bleeding. Doctors now eliminate heparin by giving patients protamine, a drug that stops heparin's anticoagulant effects. However, they are seeking a better drug because protamine carries a risk of serious side effects.

The scientists describe development of a potential new approach that involves use of microscopic beads of a polymer made from modified chitosan, a material obtained from shellfish. In laboratory tests, the beads reduced concentrations of heparin to nearly zero within 10 minutes. -- MTS

"pH-Sensitive Genipin-Cross-Linked Chitosan Microspheres For Heparin Removal"


Krzysztof Szczubialka, Ph.D.
Jagiellonian University
Kraków, Poland
Phone: 48-12-6632020


Terrorism crackdown threatens chemisty hobbyists
Chemical & Engineering News

Laws and regulations intended to crack down on terrorists, illicit drug manufacture, and other criminal activities are stifling an elite cadre of individuals who pursue chemistry as a hobby and have a home chemistry lab, according to an article scheduled for the Nov. 10 issue of Chemical & Engineering News, ACS' weekly newsmagazine.

In the article, C&EN Associate Editor Bethany Halford notes that having a lab in the basement, garage, or backyard shed was once a rite of passage for scientifically minded kids and a relatively common hobby for science curious-adults. Some of these labs have even produced significant contributions to chemistry, including vulcanized rubber and aniline dyes, the article notes.

Now, in an ongoing battle against bomb-makers and illegal methamphetamine labs, home-based chemistry is increasingly coming under attack. Thousands of people who want to pursue chemistry as a do-it-yourself hobby or home-school lesson must navigate through a maze of federal, state, and local laws that target hazardous substances -- or run the risk of fines or laboratory shutdowns, the article notes. "Not all of us are mad bombers or drug makers and we would like to be able to practice our hobby in peace if there's a reasonable way for us to figure out the guidelines," says one authority on hobby chemists.

"Underground Science"

This story will be available on Nov. 10 at:

Michael Bernstein
ACS News Service
Phone: 202-872-6042
Fax: 202-872-4370

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