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Unit 2 Medicine （第二单元 医学） 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.医学是一种关于诊断,治疗,预防疾病和伤害的科学和艺术。它的目标是帮助人们减少疾病和残疾并拥有更长,更快乐,更积极的生活。医学是从患者的临床表现积累形成的。医学方面的科学家致力于不断寻找新的药物，有效的治疗方法和更先进的技术,比如癌症纳米技术。然而,它是可能的信任在医学上太多了。某些类型的药物可能会伤害我们的身体如果我们无知的副作用。所以当我们欢迎医学领域的新发展,我们还需要谨慎的它可能带来潜在的危险。 Making a little progress（更上一层楼）-Nanotechnology takes on cancer纳米技术用于癌症治疗 By Aimee Cunningham 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.在2004年9月，美国国家癌症研究所宣布了一个重大举措，给这场古老而顽强的战斗注入了新的活力。这个被称为国家癌症研究所癌症纳米技术联盟将在未来5年投资一亿四千四百三十万美元使得纳米技术能开辟一个全新、有效的诊断及治疗癌症的途径。这是一个资金雄厚的标志，也显示出人们对纳米技术治疗癌症的关注程度已上升到最高等级的政府层面，在抗击癌症之战几乎陷入停顿之时，它来得正是时候。与近来死亡率处于下降趋势的心脏病和中风不同，自从二十世纪五十年代起，癌症的死亡率变化不大。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.”纳米技术，广义上指在0.1100纳米（即十亿分之一米）尺度上对装置结构的工程设计技术。这个技术对于癌症的发现和治疗具有广阔前景，原因有二：大小及功能。纳米大小的装置，也就是我们通常所指的纳米颗粒，能小到穿过血流直达肿瘤。这种纳米装置可以被设计用来靶向并进入肿瘤细胞。一旦进入，它们就可以携带提高癌症检测的制剂及癌症治疗的药物或基因等许多有效载荷。“如果你想将许多功能打包成能穿过血流的某样东西，你只能选择纳米颗粒。”毛罗.法拉里说，他是一位哥伦布市俄亥俄洲立大学的一名癌症纳米技术专家，同时也是国家癌症研究所的顾问。“在我脑海里，任何在将来能对癌症产生影响的都会含有纳米成分。”GETTING A GOOD LOOK （进行仔细查看）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.在癌症医药领域有这么一条原则：你发现诊治得越早，就更有机会获得良好而持久的效果。其中一位将纳米技术体现于这一原则的研究人员就是在韩国首尔延世大学工作的化学家jinwoo 郑。他一直在氧化铁中提取纳米颗粒，目的是使磁共振成像能识别出比现在发现的肿瘤更小的肿瘤。In MRI, a manager 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.在磁共振成像中，磁铁改变了氢质子的自旋，在氢质子回复到初始的自旋状态的过程中，它们发射出无线电信号。身体不同部位组织质子回复的速度不同，计算机就能将这些不同收集起来绘制成器官图像。诸如氧化铁晶体等具有磁性的纳米颗粒比无磁性的颗粒能更快地引导氢质子回到初始的自旋状态。郑说，这种快速回复就能对影像产生像增添了对比度一样的效果。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. 7Journal 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.他和他的团队意在将纳米颗粒靶向肿瘤细胞，以便于在磁共振成像中能在器官内识别小型肿瘤。在9月7日美国化学学会期刊的报告中，研究人员介绍说他们已制成了9纳米大小的氧化铁晶体，把它们附着在特异性抗乳腺癌细胞的抗体上。这个氧化铁抗体的联合体直径28纳米。研究人员向大腿部已植入人类乳腺癌细胞的小鼠尾部静脉注射靶向“造影剂”，以此来检验这种靶向“造影剂”的效果。与带有非靶向纳米颗粒的小鼠磁共振成像不同，带有靶向纳米颗粒小鼠磁共振成像显示出了癌症所在。 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.量子点是另一种类型的纳米颗粒，它们也可提供生动清晰的癌症图像。这些纳米大小的半导体颗粒体积如此之小以至于它们受到量子机械效应的控制。这些点的电子能量变得量子化。这是在亚特兰大的Emory University和乔治亚理工大学工作的生物医学工程师兼化学家聂淑明（音译）做出的解释。 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.调整纳米颗粒的大小就形成了探针，当光束照射探针时，它就会放射出大量清晰可见的能量，或者是不同颜色的光。将量子点靶向不同种类的癌细胞提高了“发现多种肿瘤细胞的可能性”，聂补充道，“这是通过使用代表不同（癌症搜寻）抗体的多种颜色来实现的”。探针的亮度足以透过皮肤发出光亮。 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.在2004年8月的自然生物技术杂志上，聂和他的团队介绍了硒化镉量子点探针，它们附着在带有前列腺癌细胞的抗体上。探针在小鼠体内以红点的方式展示了癌症所在。然而，镉是一种有毒金属，所以，在对纳米颗粒的长期毒性进行研究之前，量子点探针仅限于使用在动物及组织标本上。 BATTLE PLANS （作战计划）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. 尽管研究人员在不断探索许多纳米治疗的方法，但他们的方法万变不离其宗：针对杀死癌症。“如果能在不影响正常细胞（生长）的情况下杀死癌细胞，那就是圣杯。”斯坦福大学的化学家代宏杰（音译）说。在众多纳米颗粒中，用于这项工作的主要有三种：树枝状聚合物（树枝状纳米球）、纳米碳管及脂质体。 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.詹姆斯 R.小贝克，密歇根大学的一位内科医生，同时又是一位生物医学工程师，一直在研究树枝状聚合物直径不到5纳米的球形颗粒。它们（树枝状聚合物）有许多从内核部放射出的化学成分活跃的枝状物，其内核部能完美地结合药物及其它分子。为了将树枝状聚合物靶向癌细胞，贝克的工作小组将维生素叶酸附着在这些颗粒上。癌细胞需要大量维生素来维持其快速生长，贝克解释说，因此，癌细胞膜上有许多叶酸接收器。乳腺癌细胞、肾癌细胞、肺癌细胞及其他类型的癌细胞尤其富含这些接收器。 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.贝克的团队还把化疗药物氨甲叶酸添加进载有叶酸的树枝状聚合物中。研究人员接着将靶向药物树枝状聚合物通过静脉注射到移植了人类上皮细胞的小鼠身上。正如6月15日的癌症研究所描述的那样，科学家们发现这些直径不足20纳米的聚合物自动跟踪直捣癌细胞。这提高了药物的疗效。接受了靶向治疗的小鼠肿瘤比没有接受载有药物聚合体或只用了氨甲叶酸的小鼠肿瘤生长得慢得多。这种自我引导的功效也似乎降低了药物的副作用，比如食欲不振。贝克说，他的小组希望2006年春天能将这种聚合体在患者身上试验。 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. 纳米碳管是一种微小的碳管，它治疗癌症的途径不同。代宏杰说，它们使癌细胞燃烧。这种长150纳米，直径2纳米的管子能强有力地吸收近红外线光束并迅速将能量转变为热能。将一束近红外线激光集中照射装有溶液的纳米碳管上，不到4分钟，溶液就达到了沸点。由于肌肉在这个波长内具有透光性，将纳米管靶向癌细胞并用近红外线激光照射，就能将纳米管变成用高温杀死癌细胞的武器。同样的激光光束在穿过正常的组织时不会带来伤害。代宏杰又说：“它是一种新型的放疗。” 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. 16Proceeding of the National Academy of Sciences.由于叶酸分子的癌症搜寻功能，代宏杰的小组就利用了叶酸分子。他们将分子附着在纳米碳管上，然后测试靶向碳管对癌细胞系及正常细胞系的破坏性。癌细胞接受了带有叶酸的纳米碳管，而正常细胞却没有。随后的两分钟近红外线激光辐射只杀死了癌细胞。这是研究人员在8月16日的美国国家科学院学报中的报告。 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.脂质体是一种微小的脂质囊。它也可以被设计用来靶向癌细胞。在过去的9年中，两位华盛顿特区乔治敦医学中心的分子肿瘤学家Esther Chang and Kathleen Pirollo及他们的同事一直在研发特异性肿瘤脂质体载体系统，而且他们准备在癌症患者中展开试验。 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.研究人员将脂质体作为载体，将p53基因转染给肿瘤细胞。正常情况下，如果一个健康的细胞发生了许多突变而不能继续正常生长，p53基因就会诱发细胞自杀。然而，假如这个基因停止作用，细胞就会持续生长，最终可能变为恶性肿瘤细胞。缺少了这个功能基因还会使肿瘤细胞对放疗及化疗有抵抗力。 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.向癌症细胞转染p53基因能增加肿瘤对癌症治疗的敏感性。Esther Chang说，“如果你能使传统疗法更为有效，你或许能减少对患者的放疗或化疗量。”由于这些治疗的副作用巨大，因此对于肿瘤学家来说，这是个长期的目标。 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 liposomes load of working p53 inside.Chang， Pirollo及他们的同事将脂质体附着在一个类似于转铁蛋白的抗体碎片上。转铁蛋白是一种正常情况下向细胞输送铁的分子。肿瘤细胞需要大量的铁来给其快速生长提供能量，因此许多类型的癌细胞都携带有充足的转铁蛋白接收器，Pirollo说道。由于接收器将铁引入癌细胞，因此就将带有p53功能基因的脂质体药物载体放入细胞内。 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.在对小鼠的十余年研究中，p53基因转染与放疗的结合疗法消除了前列腺肿瘤和头颈部肿瘤。Pirollo说：“小鼠因年老而死，与肿瘤无关。”她和Chang最近得到了美国国家食品药品管理局的认可，可以在患晚期实体肿瘤的患者中进行脂质体的初步试验。 SAFE AND SOUND （安全和可靠） Despite progress, cancer nan