医学专业英语 - 2 Unit 2 Medicine

避免中式英语避免中式英语 2 2：The next one will be you.I think the meal is not delicious.I wish you have a nice day.How to spell the word?How to say that in English?Left alone in the dark, she felt very dangerous.MedicineMedicine Medicine is the science and art of diagnosing, treating, and preventing disease and injury. Its goals are to help people have longer, happier, more active lives with less suffering and disability. Medicine goes beyond the bedside of patients. Medical scientists engage in a constant search for new drugs, effective treatments, and more advanced technologies, such as nanotechnology on cancer. However, it is possible to trust in medicine too much. Some types of medicine may harm our bodies if we are ignorant of their side effects. So when we welcome new developments in medical field, we also need to be cautious of the potential danger it may bring.Making a littleMaking a little progress - Nanotechnologyprogress - Nanotechnology takes on cancer takes on cancer In September 2004, the National Cancer Institute announced an initiative to bring new blood to an old and desperate fight. Called the NCI Alliance for Nanotechnology in Cancer, the initiative will wager $144.3 million over the next 5 years that nanotechnology will open entirely new and effective strategies for diagnosing and treating cancer extend to the highest government levels, and it comes at a time when the battle against the disease seems to be at a standstill. Unlike death rates for heart disease and stroke, which have declined drastically, cancer mortality hasnt changed since the 1950s. Nanotechnology, broadly defined as the engineering of devices on the scale of tens to a couple-hundred nanometers(nm), holds promise for cancer detection and therapy for two main reasons: size and function. Nanoscale devices, often referred to as nanoparticles, are small enough to travel through the bloodstream and gain access to tumors. The devices can be designed to specifically target and enter tumor cells. Once inside, they can deliver any number of payloads, from agents that improve cancer detection to treatments such as drugs or genes. “If you want to pick multiple functions into something that can travel in the bloodstream, you have to have nanoparticles.” says Mauro Ferrari, a cancer nanotechnologist at Ohio State University in Columbus and an adviser to NCI.”Everything that will impact cancer in the future, in my mind, will have nanocomponents.” GETTING A GOOD LOOKGETTING A GOOD LOOK A maxim of cancer medicine is that the earlier you can detect and diagnose the disease, the better the chances of a favorable, lasting outcome. One of the researchers applying nanotech principles to this idea is Jinwoo Cheon, a chemist at Yonsei University in Seoul, South Korea. Hes been developing nanopaticles out of iron oxide with the goal of making magnetic resonance imaging (MRI) capable of picking out smaller tumors than it currently can. In MRI, a magnet alters the spin of hydrogen protons, which then emit radio signals as they revert to their original spins. The protons in different tissues of the body revert at different rates, and a computer can assemble those differences into images of organs. Nanopaticles with magnetic properties ,such as iron oxide nanocrystals, usher the protons to their original spins much faster than unmagnetic particles do .This quick return has the effect of adding contrast to the image, says Cheon. He and his group wanted to target the particles to cancer cells, so that small tumors could be distinguished within organs in an MRI image. The researchers report in the Sept. 7 Journal of the American Chemical Society that made 9-nm crystals of iron oxide and then tacked on an antibody that binds specifically to breast cancer cells. The iron oxide-antibody complexes were 28 nm in diameter. The researchers tested these targeted contrast agents by injecting them into the tail veins of mice that had human breast cancer cells implanted in their thighs. Unlike the MRI images of mice that received untargeted nanoparticles, the image of animals getting targeted nanoparticles revealed the cancer. Quantum dots are another type of nanoparticle poised to provide vivid pictures of cancer. These nanoscale semiconductor particles have such a tiny volume that theyre governed by quantum mechanical effects. The energies of the dots electrons become “quantized”, explains Shuming Nie, a biomedical engineer and a chemist at Emory University and the Georgia Institute of technology, both in Atlanta. Adjusting the particles sizes creates probes that, when stimulated by light, emit distinct amounts of energy, or different colors of light. Targeting the different-size quantum dots to various types of cancer cells raises the possibility of “detecting multiple tumor cells by using multiple colors labeled with different cancer-seeking antibodies.” Nie adds. The probes are bright enough to shine through the skin. In the August 2004 Nature Biotechnology, Nie and his team reported on their quantum dot-probes made of cadmium selenide decorated with antibodies that bind to prostate cancer cells. The probes revealed the cancer in mice as red blobs. Cadmium is a poisonous metal, however, so until long-term toxicity studies of the nanoparticles are conducted, use of quantum-dot probes will be limited to animals and tissue samples. http:/ PLANSBATTLE PLANS While researchers are pursuing a number of nanotechnology treatments, they are all variations on a theme: targeted cancer killing. “If you can kill cancer cells without affecting normal cells,” says Hongjie Dai, a chemist at Stanford University, “that is the Holy Grail.” Among the cast of nanoparticle characters in this work are dendrimers, carbon nanotubes, and liposomes.Dendrimers 树枝高分子聚合物Carbon nanotubes 碳纳米管Liposomes 脂质体 James R. Baker Jr., a physician and biomedical engineer at the University of Michigan in Ann Arbor, works with dendrimers, spherical polymer particles less than 5nm in diameter. They have many chemically active branches emanating from their cores structures that are perfect for holding drugs and other molecules. To target dendrimers to cancer cells, Bakers group attached the vitamin folic acid to the particles. Cancer cells need a large supply of the vitamin to maintain their rapid growth, explains Baker, so they have many folic acid receptors on their membranes. Breast, Kidney, lung, and several other types of cancer cells are particularly rich in these receptors. Bakers team also added the chemotherapy drug methotrexate to the folio acid-loaded dendrimers. The researchers then injected the targeted drug-dendrimer complexes intravenously into mice riddled with human epithelial-cell cancer. As reported in the June 15 Cancer Research, the scientists found that the complexes, which are less than 20 nm in diameter, homed in on the cancer cells. This improved the drugs efficacy: The tumors in the mice receiving the targeted therapy grew much more slowly than did those in mice given only methotrexate or an untargeted drug-dendrimer combo. The homing effect also appeared to reduce the drugs side effects, such as appetite loss. Baker says that his group is hoping to begin trails of the complexes in people during the spring of 2006. Carbon nanotubes, which are indeed tiny tubes of carbon, follow a different therapeutic path. They burn their way through cancer. The 150-nm-long, 2-nm-diameter tubes strongly absorb near-infrared light and quickly turn the energy into heat, explains Dai. Focusing a near-infrared laser on a solution containing nanotubes brought the water to a boil in 4 minutes, he reports. Because flesh is transparent to light in this wavelength range, targeting nanotubes to cancer cells and then hitting them with a near-infrared laser could turn the tubes into weapons that kill the cells with heat. The same laser light would pass through the normal tissue without harm. “Its a new type of radiation therapy.” says Dai. Dais group also turned to folic acid molecules for their cancer-seeking talents. The team fastened the molecules to carbon nanotubes and then tested the targeted tubes lethality on a cancer cell line and a normal cell line. The cancer cells took up folic acid-bearing nanotubes, but the normal cells didnt. A subsequent 2 minutes of radiation with a near-infrared laser killed only the cancer cells, the researchers report in the Aug.16 Proceeding of the National Academy of Sciences(PNAS). http:/www.pnas.org/content/102/33/11600.full Liposomes, tiny lipid sacs, can also be designed to target cancer cells. For the past 9 years, Esther Chang and Kathleen Pirollo, molecular oncologists at Georgetown University Medical Center in Washington D.C , and their colleagues have been developing a tumor-specific liposomal-delivery system, and the team is about to begin testing it in cancer patients. The researchers use liposomes to deliver a gene called p53 to tumor cells. Normally, if a healthy cell acquires too many mutations to develop properly, the p53 gene will initiate cellular suicide. If this gene stops working, however, the cell keeps growing and can become malignant. The absence of a functioning gene can also make tumor cells resistant to radiation and chemotherapy. Adding functioning p53 to cancer cells can resensitize tumors to these cancer treatments, says Chang. “If you can make the conventional therapies more effective, you may be able to reduce the amount of radiation or chemo you give to a patient.” she says. Thats a longstanding goal for oncologists because the treatments side effects can be severe.“p53是一种肿瘤抑制基因，在所有恶性肿瘤中，50%以上会出现该基因的突变。” Chang, Pirollo, and their coworkers attached to liposomes an antibody fragment thats similar to transferrin, a molecule that normally carries iron into cells. Tumor cells need a great deal of iron to fuel their rapid growth, so many types of cancer cells carry abundant receptors for transferrin, says Pirollo. Since the receptors usher iron into the cells, the action carries the liposomesload of working p53 inside. In mouse studies over almost a decade, a combination therapy of such p53 delivery and radiation treatment eliminated prostate tumors and head-and-neck tumors. “The mice died of old age, cancer-free.”says Pirollo. She and Chang recently received Food and Drug Administration approval to do preliminary tests of the liposomes in patients with advanced solid tumors.SAFE AND SOUND SAFE AND SOUND Despite progress, cancer nanotechnology still has many issues to address. For one thing, researchers say, there is a need for standardized techniques that can produce nanoparticle-based complexes that are uniform in size and structure. Only then could researchers be confident that data from various studies of a particular nanodevice are comparable. “Nanoparticles also pose a tricky problem,”says Ferrari. They could be considered drugs, biological agents, or medical devices, which complicate the approval process.“NCI is working with FDA to figure out how nanotech diagnostics and treatments for cancer should be approved.”says Grodzinski. If cancer nanotechnology does live up to its promise, the greatest impact the field may have is in how society views cancer. “Whatd like to do is to turn cancer into a controllable disease like diabetes.”says Baker. Added Ferrari, “I really think we have the ability to turn any cancer into something that we can live with for a long time without a significant loss to quality of life. Turning cancer into a chronic, manageable disease is a realistic expectation in the next decade.