Deadly Feasts - Case Notes

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Author - Linda Hensel - Spring 2000--Updated Fall 2003
 

Materials for Mad Cow Case

A simple view of the science:

The current model is that Mad Cow Disease results from an infectious particle called a prion. Prions are infectious particles made of proteins. They are not viruses or bacteria because they do not contain a nucleic acid component. How do they replicate then? They do not. They do turn good protein into a form that results in plaque and eventually leads to cell death i.e. holes in brain tissue. The analog model that I use to explain the phenomena to students is rock candy formation. Rock candy is made from a sugar solution by putting a sugar cube on a stick and allowing the sugar in the solution to precipitate onto the sugar on the stick. Imagine that the intracellular fluid in nerve cells is filled with a good protein and that good protein is in solution. When a bad form of that protein enters the cell it can cause the good protein to crystallize like rock candy formation (like Mertz’s fibrils—see page 158 in Rhodes). If plaques form in the nerve cells, the cells can no longer function and die.

Case Plan:

The video, Foreign Body, is a good introduction to the case. The narrator interviews friends and families of a few of the 25 young British folks that died of the new variant Creutzfeldt Jakob Disease (nCJD). The video talks about the epidemiological study that led to the hypothesis that the infectious agent might be in the beef. The experiment that shows a correlation between Mad Cow Disease and nCJD is shown. Scientists test this by injecting brain extracts from infected cows and infected patients into separate groups of laboratory mice. The mice from both groups demonstrate similar diseases and die.

Deadly Feasts complements the objectives of the course. Giere’s exercises 2.3 and 2.4 (page 48-49) introduce the subject matter. The text is an easy read, and students enjoy the book if the reading is spaced over a 2 to 2 ½ week segment. A summary of the text is attached. The text demonstrates the following:

    1. the process of continual discovery, one experiment leading to another and another
    2. scientists using patterns to uncover hidden likeness (Giere, Bronowski)
    3. social interaction of scientists and how relevant the interaction is to discovery (Giere, Bronowski, a wonderful complement to the Double Helix case)
    4. lives of scientists (Carlton Gajdusek is enchanting; Stanley Prusiner’s character can be compared to Jim Watson’s and other Nobel recipients)
    5. vivisection

 

The video, Brain Snatchers: Mad Cow Disease, is a wonderful summary to the case. The students get to see Joe Gibbs (the scientist that did the chimpanzee studies), Bill Hadlow (the veterinarian that noticed that scrapie in sheep resembled Kuru in the Fore tribe), and Michael Alpers (one of the scientists that worked with the Fore). The narrator does a good job of discussing the government’s role in regulating the meat industry. The presentation of the slaughterhouses is graphic—those with weak stomachs should shut their eyes!! Stanley Pruisner is mentioned, but not interviewed.

Teaching Notes:

I use reading quizzes to encourage student preparedness. After the quizzes, the groups work through the material with directed questions (see group-directed reading assignment below). Students complete the case by writing an essay that synthesizes the extended case material with the material from Giere, Lee, or Carey. Sample quizzes, group worksheets, and exam questions are attached below.

Reading Quiz 1 on Deadly Feasts--Chapters 1-3

  1. Who is Carleton Gajdusek?
  2. What/who are the Fore?
  3. In what continent was Kuru first diagnosed?
  4. Scientists look for patterns. What patterns are apparent in kuru, Creutzfeldt-Jakob disease, and scrapie?
  5. What are the three species that had the kuru-like symptoms?

Reading Quiz 3 on Deadly Feasts

  1. RNA, DNA, protein order (1/2 point for reverse)
  2. Tissues that transmit: muscle, blood, pituitary
  3. What is scrapie made of?
  4. What is iatrogenic? (1)Give Example: Cornea transplant (1)Human growth hormone (is 2, a bonus point)

Group  Reading Worksheet for Chapters 1 – 6

  1. List the patterns (and page numbers) that were seen by scientists trying to understand kuru.
  2. Track the interactions between scientists who learned what from whom?
  3. What are Koch’s Postulates? Why are they important?
  4. Was the research fast/slow? Why?
  5. How are "anthropological studies" different from "infectious disease" studies?
  6. Why were primate studies deemed necessary?

Group  Reading Worksheet for Chapters 7-13

1. What are the steps and the evidence at each step for uncovering the molecular nature of the infectious agent in TSE (transmission spongiform encephalopathy)?

2. Give examples of science interfacing with politics. Are the interactions positive, harmful or both? (What does this question have to do with the purpose of this course?)

3. Using the entire text, list some of the examples of cross-species infection. Why is this of scientific interest?  . . . of interest to government officials?

Bonus Point Assignment: Find a primary research article on prions or TSE.  Work the six steps that are described in Giere's Chapter 6.

The final exam consists of two parts. Part I is worth 80 % of the final, and Part H is worth 20 % of the final. The exam consists of two essays. The essays should be double-spaced and @. There is no limit on the length of the essays.