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Archive - Jan 23, 2012


Patterns of Chromosome Abnormality Seen in Cancer

A healthy human genome is characterized by 23 pairs of chromosomes, and even a small change in this structure — such as an extra copy of a single chromosome — can lead to severe physical impairment. So it's no surprise that when it comes to cancer, chromosomal structure is frequently a contributing factor, says Professor Ron Shamir of the Blavatnik School of Computer Science at Tel Aviv Universitu (TAU). Now Professor Shamir and his former doctoral students Dr. Michal Ozery-Flato and Dr. Chaim Linhart, along with fellow researchers Professor Shai Izraeli and Dr. Luba Trakhtenbrot from the Sheba Medical Center, have combined techniques from computer science and statistics to discover that many chromosomal pairs are lost or gained together across various cancer types. Moreover, the researchers discovered a new commonality of chromosomal aberrations among embryonic cancer types, such as kidney, skeleton, and liver cancers. These findings, published on June 29, 2011 in Genome Biology, could reveal more about the nature of cancer. As cancer develops, the genome becomes increasingly mutated — and identifying the pattern of mutation can help us to understand the nature and the progression of many different kinds of cancer, says Professor Shamir. As cancer progresses, the structure of chromosomes is rearranged, individual chromosomes are duplicated or lost, and the genome becomes abnormal. Some forms of cancer can even be diagnosed by identifying individual chromosomal aberrations, notes Professor Shamir, pointing to the example of a specific type of leukemia that is caused by small piece of chromosome 9 being moved to chromosome 22. When analyzing many different kinds of cancer, however, the researchers discovered that chromosomal aberrations among different cancers happen together in a noticeable and significant way.

Compounds in Mate Tea Kill Colon Cancer Cells In Vitro

Could preventing colon cancer be as simple as developing a taste for yerba mate tea? In a recent University of Illinois study, scientists showed that human colon cancer cells die when they are exposed to the approximate number of bioactive compounds present in one cup of this brew, which has long been consumed in South America for its medicinal properties. "The caffeine derivatives in mate tea not only induced death in human colon cancer cells, they also reduced important markers of inflammation," said Dr. Elvira de Mejia, a University of Illinois associate professor of food chemistry and food toxicology. That's important because inflammation can trigger the steps of cancer progression, she said. In the in vitro study, Dr. de Mejia and former graduate student Sirima Puangpraphant isolated, purified, and then treated human colon cancer cells with caffeoylquinic acid (CQA) derivatives from mate tea. As the scientists increased the CQA concentration, cancer cells died as a result of apoptosis. "Put simply, the cancer cell self-destructs because its DNA has been damaged," she said. The ability to induce apoptosis, or cell death, is a promising tactic for therapeutic interventions in all types of cancer, she said. Dr. de Mejia said they were able to identify the mechanism that led to cell death. Certain CQA derivatives dramatically decreased several markers of inflammation, including NF-kappa-B, which regulates many genes that affect the process through the production of important enzymes. Ultimately cancer cells died with the induction of two specific enzymes, caspase-3 and caspase-8, Dr. de Mejia said. "If we can reduce the activity of NF-kappa-B, the important marker that links inflammation and cancer, we'll be better able to control the transformation of normal cells to cancer cells," she added.

New Biochip Measures Glucose in Saliva

For the 26 million Americans with diabetes, drawing blood is the most prevalent way to check glucose levels. It is invasive and at least minimally painful. Researchers at Brown University are working on a new sensor that can check blood sugar levels by measuring glucose concentrations in saliva instead. The technique takes advantage of a convergence of nanotechnology and surface plasmonics, which explores the interaction of electrons and photons. The engineers at Brown etched thousands of plasmonic interferometers onto a fingernail-size biochip and measured the concentration of glucose molecules in water on the chip. Their results showed that the specially designed biochip could detect glucose levels similar to the levels found in human saliva. Glucose in human saliva is typically about 100 times less concentrated than in the blood. “This is proof of concept that plasmonic interferometers can be used to detect molecules in low concentrations, using a footprint that is ten times smaller than a human hair,” said Dr. Domenico Pacifici, assistant professor of engineering and lead author of the paper published online on December 26, 2011 in Nano Letters, a journal of the American Chemical Society. The technique can be used to detect other chemicals or substances, from anthrax to biological compounds, Dr. Pacifici said, “and to detect them all at once, in parallel, using the same chip.” To create the sensor, the researchers carved a slit about 100 nanometers wide and etched two 200 nanometer-wide grooves on either side of the slit. The slit captures incoming photons and confines them. The grooves, meanwhile, scatter the incoming photons, which interact with the free electrons bounding around on the sensor’s metal surface.