SHOW 301: Botulin Toxin: Rx For Dystonia
A lethal toxin injected in just the right muscle turns out to be an effective medical treatment for two people who suffer from a severe muscle disorder called dystonia. The manager of an R&B band can no longer control her voice, and finger muscle spasms have effectively ended the professional career of a promising violinist. For both patients, the prescription is surprising -- a minute dose of Clostridium botulinum, the deadliest poison in the world.
Activity: Cultured Bacteria
Notes & Discussion
Report From the Field: Ed Schantz, Biochemist from the Food Research Institute at the University of Wisconsin at Madison
ACTIVITY: CULTURED BACTERIA
The bacteria that produce the deadly botulin toxin have certain needs that must be met in order for it to survive. These needs include food, moisture and an oxygen-free environment. In Part 1, you'll grow bacteria found in your surroundings. In Part 2, you'll observe the effectiveness of tap water and bouillon as a culture medium. You'll also make some inferences about how bacteria can travel.
PART 1: POTATO, POTATO...
- 3 metal can lids
- aluminum foil
- 3 raw potato pieces
- wax marker
Note: Although these bacteria are not deadly like botulinum, it's still a good idea to observe caution when handling any unknown substance. For a guaranteed bacteria-rich contamination, try using a wet cotton swab to transfer bacteria from souring milk or the bottom of a shoe to potato pieces.
- Because bacteria grows well in warm, moist, airtight containers, you'll need to prepare culture chambers. Clean, rinse and dry three metal container lids to use as the chambers.
- Use a marker to label the bottoms of the chambers as 1, 2, 3. Include the name of your lab group.
- Place one small piece of potato in each of the three chambers.
- Cut out three circles of aluminum foil, each about 12 cm in diameter. Place a circle of foil over each of the chambers and crimp down the sides to form an airtight seal. Present these sealed chambers to your instructor for sterilizing.
- When the sterilized chambers are returned, set chamber #1 aside.
- Open chamber #2, and touch the potato with your finger tip (this is one time dirty hands are encouraged). Reseal the chamber and set it aside. Make sure that the foil does not touch the potato.
- Open chamber #3, and leave it unopened for an hour. Then reseal it and set it aside, making sure the foil does not touch the potato.
- Store chambers in a warm place, out of direct sunlight.
- After three days, open each of the chambers.
- Caution: Do not touch the potato or remove the bacteria colonies!
- Count the number of small bacteria colonies (lightly-colored dots) found on the potato's surface.
- Which potato had the most colonies?
- What was the source of the colonies that were observed?
- What was the role of chamber #1?
- Why was a potato needed for the growth of these organisms?
- Why were the culture chambers sterilized?
- Answers all will vary, but most likely it will be chamber #2.
- Chamber #1, accidental contamination; chamber #2, bacteria living on skin surface; chamber #3, bacteria transported by air
- A source of nutrition
- Remove any pre-existing bacteria in the chamber or on the potato.
PART 2: BACTERIA FROM BOUILLON
- prepared bouillon soup
- 4 test tubes
- test tube rack
- wax marker
- Form a lab team of four students.
- Student A assembles the needed materials at the activity desk.
- Student B labels the test tubes 1, 2, 3 and 4. Mark the halfway level on each of the four test tubes.
- Student C fills tubes 1 and 2 to the halfway level with the cooled bouillon solution.
- Student D fills tubes 3 and 4 to the halfway level with tap water.
- Student A places a small cotton plug in the mouths of tubes 2 and 4. Leave the mouths of tubes 1 and 3 unobstructed.
- Student B places the tubes in a test rack and stores the setup in a location where the tubes will not be disturbed. After one week, examine the tubes.
- Which tubes appear cloudy?
- Which tubes appear clear?
- What might account for the cloudy appearance of some of the tubes?
- Where did the microbes come from?
- Was the bouillon necessary for microbe growth? Explain.
- How did the cotton plug affect microbe growth?
- Tube 1
- Colonies of microbes
- The air
- Yes; it was a food source for the microbes.
- It prevented the airborne microbes from infecting the solutions.
Part 1: In this experiment, students construct a culture chamber and use it to grow bacteria found in their surroundings.
- You may wish to substitute petri dishes for the classroom-made culture chambers.
- Prior to the activity, cut the raw potato into pieces that can fit inside the culture chambers without touching the aluminum foil cover.
- To sterilize the chambers, place them in an autoclave of 15 lbs. of pressure for ten minutes. The culture chambers also can be sterilized in a pressure cooker for 20 minutes.
Part 2: Students observe the effectiveness of tap water and bouillon as a culture medium.
- Prepare a supply of bouillon ahead of time. Use several different kinds of bouillon and have students compare the effectiveness of each medium.
- Divide the class into cooperative learning groups of four students each. Assign specific roles as described in the activity.
- If a test tube rack is not available, have students set test tubes in a sturdy beaker or can.
- Caution students against removing the cotton plugs in the tubes in which microbe growth is observed.
- It's a killer: If one ten-thousandth of a milligram of the botulin toxin is the fatal dose for one person, how many people could one milligram kill? (10,000)
- One gram? (10 million)
- If 10 million people could die from one gram, and 28.3 grams are equivalent to one ounce, about how much toxin (in ounces) would it take to kill a population the size of the U.S., which numbers about 250 million? (less than one ounce -- 10 million x 28.3 = 283,000,000)
- How many people could 8 oz. (1 cup) kill? (about 2,264,000,000)
- Given a world population of 5.5 billion, about how many cups would be needed to eliminate the entire population? (a little over 2 cups)
NOTES & DISCUSSION
- Botulism is a type of food poisoning caused by the botulin toxin, produced by the bacterium Clostridium botulinum. The word botulism comes from the Latin word botululs (sausage), derived from the early association of sausage with this type of food poisoning. Although these bacteria are common in soil, they are harmless inhabitants of an oxygen-saturated environment. However, under conditions that include oxygen-free surroundings, the bacteria grow and release several types of neurotoxins.
- When injected in minute amounts into the contracting muscle, the botulin toxin blocks the nerve impulses transmitted from the nerve endings of the targeted muscle, thereby weakening or paralyzing it. For certain kinds of muscle disorders, botulin toxin is the treatment of choice. But the method is still only a treatment, not a cure, and must be repeated when the dose wears off.
REPORT FROM THE FIELD: ED SCHANTZ, BIOCHEMIST FROM THE FOOD RESEARCH INSTITUTE AT THE UNIVERSITY OF WISCONSIN AT MADISON
Dr. Ed Schantz and his assistant Eric Johnson have the distinction of manufacturing the most poisonous substance in the world -- botulin, a toxin so deadly that one ten-thousandth of a milligram is enough to kill a human being. Yet Schantz, who has been producing the lethal toxin for almost 50 years, has managed to escape any ill effects. As a precaution, he and others in his lab must first become immunized to the toxin.
How did Schantz get into the unusual job of making botulin toxin? The story begins during World War II, when Schantz was an Army officer with the U.S. biological warfare program at Fort Detrick in Maryland, where he was assigned to find out whether the toxin could be used as an agent of war against U.S. troops (it could not). After the war, Schantz continued to concentrate on research he'd begun on using botulin to treat dystonias. In 1968, Schantz suggested using botulin toxin as an alternative to surgery for strabismus, a condition of crossed eyes caused by overactive eye muscles. This first successful test led to what is now fairly routine treatment for similar muscle disorders. In fact, all of the botulin now administered to treat dystonias was produced using a complex brewing process developed by Dr. Schantz.
Looking to the future, Schantz sees more promising uses for the toxin. Neurologists and other researchers are currently studying the use of the toxin in the treatment of cerebral palsy and multiple sclerosis. Preliminary success has also been reported by a neurologist who is treating patients with severe stuttering by injecting the toxin into their vocal cords.
FOR MORE INFORMATION
Dystonia refers to a disorder characterized by involuntary muscle contractions. Though various muscles may suffer, dystonia more commonly affects those in the neck, eyelids, hand (ex. writer's cramp) or vocal cords (dysphonia).
For information on any of the specific dystonias, or more about this and other treatments, contact the Dystonia Medical Research Foundation, One East Wacker Drive, Suite 2900, Chicago, IL 60601-2098 (phone 312-755-0198).
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