※ [本文转录自 NTUmed91work 看板] 作者: montein (嘿，终於考完了) 看板: NTUmed91work 标题: [勘误] 流病III 3/14第三节 时间: Mon Apr 4 21:01:18 2005 其实严格说起来应该算补充 Dear Students: The Answers: A. 第一个不懂处:老师讲义上有提到Post hoc ergo propter hoc这句话, 能否请问老师一下这句话究竟是什麽意思呢? CCKing Answers: 1. Wordings: Those are from Latin words Post Hoc : After the Event Ergo: Therefore Propter Hoc: Because of this 2. True meaning and Definition: Coincidental Correlation (post hoc ergo propter hoc ) ----------------------------------------------------------------------------- Definition: The name in Latin means "after this therefore because of this". This describes the fallacy. An author commits the fallacy when it is assumed that because one thing follows another that the one thing was caused by the other. 3. Examples: (i) Immigration to Alberta from Ontario increased. Soon after, the welfare rolls increased. Therefore, the increased immigration caused the increased welfare rolls. (ii) I took EZ-No-Cold, and two days later, my cold disappeared. 4. Proof: Show that the correlation is coincidental by showing that: (i) the effect would have occurred even if the cause did not occur, or (ii) that the effect was caused by something other than the suggested cause. 5. References (Cedarblom and Paulsen: 237, Copi and Cohen: 101) B. 第二个有问题处:老师上课时有说到当初SARS事件爆发时为了找etiology, 於是开始把感染者的各组织去作细胞培养分析， 结果在病人的肺泡细胞周围发现有许多muti-nuclear giant cell. 老师上课时说这是一个个细胞融合在一起变成的, 然而相关的机转与这现象代表着什麽意义? CCKing Answers: 1. They found that Multi-Nuclear Giant Cells( MNGC) have the staining of SARS-coronavirus. In other words.this virus caused the cell pathology that the cytoplasm of each cells were destroyed so that you can find the NGC under the microscope to prove the CAUSAL relationship between the agent and the pathology. 2. The 2nd example is AIDS that HIV also caused MNGC which can be found in demantia patients that also explains why some AIDS patients showed up CNS problems later on. This is from the findings of UC San Francisco. In other words, MNGC demonstrated a type of pathology in the process of viral pathogenesis.Is it clear to you now? The interesting part is that numerous HIV virus particles accumulated in those MNGC under electronic microscope that might be the part of the reasons to lead pathology. C. 第三个不清楚处:也是老师上课时讲SARS时提到的,SARS发病後第四天、第十一天、 第十三天采集到的血液检体，所做的一些检测其反应逐渐由阴性到 阳性，这是证明引起ＳＡＲＳ的是冠状病毒的最好证据.在这里关於 老师提的检测我有些地方不是很懂,能否请老师为我们解说一下这些 检测阴阳性与冠状病毒之间的关系呢? CCKing Answers 1. If you like to show one microbe is an etilogical agent, two major scientific proof thinking pathway and methods you can do: (a) To directly detect microbial Nucleic acid or antigen (b) To detect the immune response of this etiological agent such as the antibody because of the "specificity" of immune responses - only respond to A for producing Anti-A antibody 2. If the serum of SARS patients showed "negative" antibody around day 2 of the onset of fever but turned to positive on day 20, this patient must acquried SARS-Coronavirus. The key point is that you need to collect the serum samples at DIFFERNT TIME POINTS to show the CAUSAL relationship. 3. The problem, also the best teaching example, that Chinese Hong Kong University made the mistake to think metapneumovirus was the etiological agent is that they only one time point without temporal relationship (ie. coincidentally happened rather than true cause). Is that clear to you. 4. To prove what is the true cause for the diease in infectious disease epidemic is very important because the prevention and control strategy might be differnet and you can save many numbers of more precious life if your Cause is the True Cause. I will put more slides on Tuesday beause I was too busy in one paper revision for one young professor this weekend but I have NOT forgot the slides that I will revise and put them on the web for you. THanks for your learning and reaching our educational goal to have more scientific discovery in the future. --

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