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The Sleeping Beauty tranposon (SB-Tn) system, a gene therapy technology that avoids the pitfalls of transferring genes with viruses, shows promise in laboratory experiments for correcting the gene defect responsible for sickle cell disease (SCD), scientists in Minnesota are reporting.
In the study, scheduled for the June 12 issue of ACS’ Biochemistry, a weekly journal, Clifford J. Steer and colleagues note that viruses have gotten most attention as possible vectors, or delivery vehicles, for replacing defective genes with normal copies. In SCD, a mutation in the gene that encodes for beta globin results in abnormal hemoglobin that gives red blood cells a sickle shape. Concerns about potential risks and other problems with viral vectors, however, have become barriers to use of gene therapy.
Using laboratory cell cultures, the researchers showed that SB-Tn system could transfer normal beta globin genes into cells. The system, named for a fish gene reawakened by other researchers in 1997 after 15 million years of dormancy, fulfills essential requirements for gene therapy, the report states. Cells take up genes transferred with SB-Tn technology, the genes produce beta globin in stable fashion for long periods, and the genes are inherited and passed along as cells reproduce. Scientists term Sleeping Beauty as a transposon, or a “jumping gene” because it can jump from one location on a piece of DNA to another.
The first systematic study of a new group of explosives has concluded that the materials are so shock sensitive — apt to detonate if struck or heated — that the legendarily touchy nitroglycerin seems a pillar of stability by comparison. Conducted by Thomas M. Klapötke and colleagues in Germany, the study is scheduled for the May 30 issue of the Journal of the American Chemical Society, a weekly publication.
In the study, researchers focus on newly developed chemical analogues, or variants, of two common high explosives in which carbon atoms have been replaced by atoms of silicon, the element in ordinary beach sand. Because of the extreme sensitivity of the compounds, which the researchers did not expect, only a limited number of tests could be performed before samples exploded.
A sample of one compound, for instance, exploded when touched gently with a small plastic laboratory spatula. Another sample exploded under a microscope. Measurements showed that the silicon analogue was more than 3 times more sensitive to impact than the parent compound. The report states that the compound is “one of the most dangerous materials, and tends to explode on the slightest impact.”
Journal: American Chemical Society
Journal Article: “The Sila-Explosives Si(CH2N3)4 and Si(CH2ONO2)4: Silicon Analogues of the Common Explosives Pentaerythrityl Tetraazide, C(CH2N3)4 and Pentaerythritol Tetranitrate, C(CH2ONO2)4”
Scientists in Indiana are reporting progress toward development of low glycemic and slowly digestible starch, a form of starch that would be less apt to cause the spike in blood sugar — and perhaps sharp hunger pangs — that many individuals experience after eating bread, baked goods, and other high-carbohydrate foods.
In a study scheduled for the May 30 issue of ACS’ Journal of Agricultural and Food Chemistry, a bi-weekly journal, Bruce R. Hamaker and colleagues note that “starch with a slow digestion property would provide for extended glucose release along with a low glycemic response and, thus, may have commercial application as a healthy ingredient of processed foods. There are no commercial slowly digestible starch-based products available in the current food market to our knowledge.”
The study describes an enzyme treatment used in laboratory experiments to modify the structure of corn starch. It increased the amount of slowly digested starch by up to 13.5 percent while reducing the levels of rapidly digested starch by up to 19.7 percent. The next step will be to test these materials in human trials.
Journal: Agricultural and Food Chemistry
Journal Article: “Starch with a Slow Digestion Property Produced by Altering Its Chain Length, Branch Density, and Crystalline Structure”
Scientists in California are reporting an advance toward one of the futuristic goals nanobiology and nanomedicine ¬ developing technology for “wiring” together individual cells and connecting cells via nanowires to external sensors and other devices.
In a study scheduled for the June 20 issue of Journal of the American Chemical Society, a weekly publication, Bruce R. Conklin and Peidong Yang and colleagues report what they term the first demonstration of a direct nanowire connection to individual mammalian cells without the use of force that can damage or kill cells. They connected human embryonic kidney cells and mouse embryonic stem cells to silicon nanowires, using an approach in which the wires penetrated into cells naturally as the cells grew in cultures. The cells survived for days, and researchers were able to derive and maintain heart muscle cells from the mouse embryonic stem cells.
“Direct interconnection of the cells to the external world by interfacing nanomaterials may afford great opportunities to probe and manipulate biological processes occurring inside cells, across membranes, and between neighboring cells,” their report states. “Our results suggest that the nanowires can be potentially utilized as a powerful tool for studying intra- and inter-cellular biological processes.”
When considering perceived obstacles to coveted achievements — the four minute mark when running a mile or the speed of sound in aviation — a biological barrier that frustrates efforts to develop critically-needed new drugs for brain diseases makes many others pale in comparison. That security-minded firewall in the brain, called the blood-brain barrier, is the topic of a fascinating story scheduled for the June 4 issue of Chemical & Engineering News, ACS’ weekly newsmagazine.
The article, written by C&EN Associate Editor Sarah Everts, explains that the blood-brain (BBB) is a tightly knit layer of cells lining the 400 miles of blood vessels in the brain. Intended to protect delicate nerve cells from potentially toxic compounds in the blood, and assure a steady-state chemical environment, the BBB also prevents most actual and would- be drugs from entering the brain.
In doing so, the BBB frustrates efforts by scientists to develop new drugs that could benefit millions of people with clinical depression, stroke, Parkinson’s disease, and a range of other conditions. The article describes research efforts to develop medications that are better at penetrating the barrier.
This pioneering conference on one of the hottest topics in chemistry will be held June 26-29, 2007 at the Capital Hilton hotel in Washington, DC.
News media registration is now open for the 234th ACS national meeting, which will be held in Boston, MA on August 19-23, 2007 at the Boston Convention and Exhibition Center and more than a dozen hotels across the city. More than 16,000 scientists and others are expected to attend this scientific extravaganza. There will be more than 9,500 presentations on new discoveries in chemistry, health, medicine, energy, environment, food, and other fields. The theme: “Biotechnology for Health and Wellness.”
The American Chemical Society — the world’s largest scientific society — is a nonprofit organization chartered by the U.S. Congress and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.
Journal: Chemical & Engineering News
Journal Article: “Brain Barricade: Tackling the grueling challenge of getting brain therapies across the blood brain barrier”