A Blog devoted to progressive politics, environmental issues, LGBT issues, social justice, workers' rights, womens' rights, and, most importantly, Cats.

Wednesday, November 07, 2007

Science - Snippets From Science News

When politics just makes you too furious for your own good health, turn to Science News, I say. Whether it's the magazine itself (an excellent summation of work going on in all the different fields) or to any other source of news about the culmination of human endeavour in scientific fields, it will fill you with renewed hope for the human species. Caveat: Not all articles are available in the online edition. However, you can't go wrong subscribing to the magazine. It's well-written, a succinct and elegant compilation of science facts. Besides, you can do the rest of the world a favour and either hand them over to your sprog or someone else's sprog, or, if you're sprogfree, leave them in your doctor's or dentist's waiting room. Think of it as saving the masses from the brain-rot induced by People magazine.

Further caveat: These are my own precis of the articles I've read, containing only the information that I found useful or informative. For the full article, please see Science News.

Nanotechnology joins the fight against cancer The National Cancer Institute has established funding to create the NCI Alliance for Nanotechnology in Cancer ( an initiative to add nanotechnology to the arsenal of tools for diagnosing and treating cancer. Nanoparticles, which are small enough to travel through the bloodstream and gain access to tumours, can enter tumour cells and deliver agents to improve cancer detection or treatments such as drugs or genes. Cheon Jinwoo, a chemist at Yonsei University in Seoul, South Korea, has been developing nanoparticles out of iron oxide. Such nanoparticles could help MRI detect tumours at a much earlier stage of development. Early detection makes all the difference in treating cancer. Quantum dots (nanoscale semiconductor particles) change energy levels in discrete steps, and can be made to emit different colors, according to Nie Shuming, a biomedical engineer and chemist at Emory University and the Georgia Institute of Technology in Atlanta. Nie and his gteam have made quantum dot-probes of cadmium selenide decorated with antibodies that bind to prostate cancer cells. The probes effectively revealed cancer in the mice as red blobs.

James R. Baker Jr., a physician and biomedical engineer at the University of Michigan in Ann Arbor, uses dendrimers (spherical polymer particles under 5 nm in diameter) with multiple chemically active branches emanating from their cores. Folic acid is attached to the particles. This makes them attractive to cancer cells, which need large supplies of the acid to fuel their growth. Baker and his team also added the chemotherapy drug methotrexate to the dendrimers and injected them into mice with human epithelial-cell cancer. The dendrimers homed in on the cancers, retarding their growth significantly, compared to mice given either only methotrexate or given an untargeted drug-dendrimer. The homing effect also appeared to reduce the drug's side effects, such as appetite loss. Epithelial ovarian cancer is the most lethal gynecologic cancer accounting for more deaths than endometrial and cervical cancers combined. Ovarian cancer is especially difficult to diagnose as it is not associated with any specific signs or symptoms; the vast majority of women are diagnosed in an advanced stage. The American Cancer Society estimated that 22,220 new ovarian cancer cases would occur in 2005 (equivalent to 1 new case every 23 minutes) with an overall mortality rate of 6 percent. The 5-year survival rate for women who are diagnosed with an advanced stage ovarian cancer is only 15 to 20 percent, whereas the 5-year survival rate for women who are diagnosed in an early stage of the disease approaches 90 percent.

Dai Hongjie, a chemist at Stanford University, is working with carbon nanotubes that burn their way through tumours. Using near-infrared lasers to heat the tubes after targeting them to cancer cells using folic acid, Dai's team found that they could kill the cancer cells without damaging nearby normal cells. Flesh is transparent to light at the wavelength range used by Dai's team, so no adverse reaction occurred.

Esther Chang and Kathleen Pirollo, molecular oncologists at Georgetown University Medical Center in Washington, D.C., have developed a tumour-specific liposomal delivery system. They use liposomes (tiny lipid sacs) to deliver a gene called p53 to tumour cells. The p53 gene induces apoptosis. If it stops working, the cell grows abnormally and can become malignant. A dysfunctional p53 gene can also render tumour cells resistant to conventional cancer treatments. Adding a working p53 gene to a tumour can cause the tumour to respond to conventional cancer therapy. Chang and Pirollo used an antibody fragment similar to transferrin to target the cancer cells. Transferrin carries iron to cells. Cancerous cells need large supplies of iron (as well as folic acid) to fuel their growth.

Ram Sasisekharan, a biological engineer at the Massachusetts Institute of Technology, used a two-part nanoscale liposome, 80-200 nm in diameter, to transport both a chemotherapy drug and an anti-angiogenesis drug into tumour cells. Angiogenesis is the process of growing new blood vessels that is carried out by tumours to enable their rapid growth. Sasisekharan's liposome comprised an inner polymer nanoparticle that linked to the chemotherapy drug, encapsulated in a liposome, with the anti-angiogenesis drug occupying the space between the two. The liposome releases the anti-angiogenesis drug into the tumour, shutting down its vascular system. The inner core of the liposome is now trapped in the tumour and releases its chemotherapy drug, killing the tumour.

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