[36]Pollutants.

感谢收听,期待你对本期节目的评论留言哦～ 2017.5.5 Economist Science and Technology Pollutants Fatal attraction The missing link between pollution and heart disease may have been found. WHY air pollution causes lung disease is obvious. Why it also causes heart disease is, though, a conundrum [kəˈnʌndrəm]谜语; 难解的问题. One suggestion is that tiny particles of soot煤烟 migrate through the lungs, into the bloodstream and thence [ðens]之后 to the walls of blood vessels, where they cause damage. Until now, this has remained hypothetical. But a study published in ACS Nano, by Mark Miller of Edinburgh [ˈednˌbɜ:rə]University, suggests not only that it is correct, but also that those particles are specifically carried to parts of blood vessels where they will do maximum damage—the arterial plaques [ɑ:'tɪərɪəl p'lɑ:k]动脉斑块 associated with cardiovascular[ˌkɑ:diəʊˈvæskjələ(r)] 心血管的disease. One reason the particle-migration hypothesis has proved hard to confirm is that it is tricky to follow soot around the body. Soot is made of carbon, and that element, when finely精细地 divided and at low concentration浓度, is difficult to isolate [ˈaɪsəleɪt]分离 in biological material. Instead, Dr Miller and his colleagues used soot-sized particles of gold for their experiments. These are easy to detect, even at low concentrations, by means such as mass spectroscopy[spekˈtrɒskəpi]光谱学 and Raman spectroscopy拉曼光谱学. Also, gold is chemically inert[ɪˈnɜ:t] [化]惰性的 and therefore unlikely to be toxic. This is important, because some of Dr Miller’s experimental animals were people. The first group of these human guinea pigs实验对象，试验品 were 14 healthy men. Each was asked to exercise for two hours while inhaling[ɪnˈheɪl]吸入 air containing particles of gold. Dr Miller and his colleagues then monitored监控 the volunteers’ blood and urine[ˈjʊərɪn]小便 for 24 hours, and again three months later. As expected, none of the volunteers showed signs of gold in their blood or urine before their exposure to the particles. All but two, however, did so 24 hours later. This proved that tiny particles can indeed migrate from the lungs into the circulation. Moreover, at the three-month recheck, the concentrations of gold in their bodily fluids remained more or less unchanged. Gold, once breathed in, is retained. This experiment did not, however, tell Dr Miller where the particles were going and how they (or, rather, their carbon equivalents) can cause heart problems. He and his colleagues suspected that the culprits['kʌlprɪt]肇事者; 引起问题的事物 were immune-system cells called macrophages[ˈmækrəfeɪdʒ] 巨噬细胞. These exist to engulf吞没 foreign bodies[医] 异物，外物, such as bacteria, and would thus be quite capable of swallowing small particles of carbon or gold. They are also involved in inflammatory[ɪnˈflæmətri] responses炎症反应, which are helpful when short-lived (such as in reaction to a wound) but threatening when chronic[ˈkrɒnɪk]慢性的 (as in the inflammation[ˌɪnfləˈmeɪʃn] associated with arterial plaques). Dr Miller and his colleagues thus wondered if their particles were being carried specifically to those plaques by macrophages. Preliminary[prɪˈlɪmɪnəri]初级的 experiments on mice genetically engineered to be prone [prəʊn]有……倾向的，易于 to vascular [ˈvæskjələ(r)] 血管的disease suggested they were. Dr Miller made these animals breathe in gold particles twice a week for five weeks. Then, a day after the final exposure, he killed and dissected解剖 them. He found that a given mouse’s diseased arteries contained five times as much gold as its healthy ones did. To see if something similar is true in people, the team then recruited three further volunteers. In this case, those signed up were the opposite of healthy. They were patients with plaque-clogged arteries, who were at risk of suffering a stroke. This particular trio三人一组 were asked to breathe in the gold dust 24 hours before they underwent surgery intended to clear their plaques and unblock除去障碍 their constricted[kənˈstrɪkt]收缩 vessels. Dr Miller and his colleagues were thus able to examine the extracted萃取的 plaques for the presence of gold—which they found, as by now they expected to, in abundance. It remains to be determined whether particles of carbon behave in the same way as particles of gold. But, given carbon’s high chemical reactivity化学反应活性 compared with gold’s, it is a fair bet that macrophages will be even more likely to notice and swallow it. So, though Dr Miller’s work does not point towards a better treatment for pollution-induced引起 cardiovascular disease, it does add weight to the arguments of those who worry about levels of air pollution. 1.Where is the love----Justin Timberlake&Black Eyed Peas