Larry Lack, San Rafael (CA) H.S.
Intro: Use the Gulf War incident in which 2 Marine LAV's (Light Armored Vehicles) were destroyed by friendly fire from a pair of AH-64 Apache gunships because the LAV's had not placed the large inverted V's of reflective tape on the sides of their vehicles which would have been picked up by the gunships' infrared Target Acquisition Systems and identified them as "friendly".
Correlation with Birding, Animal recognition systems, etc.
INQUIRY: How can a human create the billions of antibodies (when their numbers of total genes available is only a small fraction of that) to provide for the genetic specificity of the multitude of potential pathogens in nature?
Have pairs of students develop at least 2 yes/no questions designed to gather background data on the question. After sufficient background info has been developed, the pairs conference to define what it is they know, what further questions they need to ask for clarification, or whether they are ready to propose and test a hypothesis. [Several hundreds of gene sequences mix and match to provide antibody response to a particular antigen.] Antibodies, it turns out, are composed of four small proteins called chains. Each antibody possesses two identical heavy chains and two identical light chains. An intertwining light chain and heavy chain form an active site capable of recognizing an antigen, so each antibody molecule has two identical recognition sites. The code for the heavy chains resides in four sets of mini-genes located in widely separated parts of the nucleus. Antibody diversity springs from the size of these mini-gene families and their ability to mix a variety of gene sequences to provide almost limitless antibody response. After a correct hypothesis has been proposed, have students debrief the thinking process they used. [Metacognition; thinking about how they were thinking] What kind of thinking process did you use? Deductive? Inductive? What Yes questions were most helpful, what No questions were helpful, what hypotheses had to be discarded, what were your responses to having to discard a hypothesis, etc?
CONCEPT ATTAINMENT: Diseases for which we have assistance.
Tell the class that you have a concept in mind and will give them several clues which contain all the traits and characteristics of the concept, as well as some clues which do not have the traits of the concept. They are to consider the clues and develop as many hypotheses about what the concept is as they can. They can test their hypotheses only by supplying more clues to either column.
Ask students to look at the clues, develop their multiple hypotheses, and invite them to test their ideas by suggesting another clue for either column. Then provide more clues such as the following:
| Polio || Potassium|
| Smallpox || Asteroids|
Inquire as to how many students have had to abandon their hypotheses and then remind them to look again at all the clues and compare what the exemplars have in common that the non-exemplars do not.
| Typhoid fever || Influenza|
| Tuberculosis ||AIDS|
Continue until it is obvious, based upon their supplying more clues correctly, that most of the class has "attained" the concept, then invite a students to state their specific hypothesis. Ask for confirmation by soliciting further clues for both columns; then proceed with a metacognitive analysis, or "unpacking", of the things they thought about in solving the problem. Which clues were most helpful; which clues caused them to have to reject their favorite hypotheses, how did they respond to having to start anew, etc.?
COOPERATIVE LEARNING: Jigsaw I--Components of the Immunological Reaction System
Each of the four students of each Home Team will volunteer to take on the responsibility for learning all about one of the following four topics:
T & B Cells
All the Antigen "specialists" from each Home Team then gather together, as do all the "specialists" from each of the other three areas, where they study the relationships of their area to immunity, prepare to teach their Home Team colleagues about their specialty, then reconvene in their Home Teams, where they will have 3 minutes each to teach the essentials of their area. They then check for understanding by asking a question, pausing, then calling on a colleague to respond.
Administer a short quiz containing at least one key question from each area. Students will receive credit for their individual score as well as the team average, thus placing an emphasis on each student taking the responsibility for ensuring each of their teammates is well informed.
Set up a "Country Fair" of Apple II and Macintosh computers to have the students use the following programs:
LAB: Use of lectins for recognition of cells
- Using Heath BIOSOLVE software; Infectious Disease program, proceed with the following scenario: You are a team of physicians working in a clinic. A patient comes to your office with a fever and additional symptoms that lead you to a preliminary diagnosis of bacterial infection. Blood, urine, and stool specimens are taken and cultured. A decision needs to be made about the appropriate antibiotic for the patient's infection. The team must consult the Infectious Disease Data Base to get answers.
- Another Heath, Infectious Disease program. A patient comes to your office complaining of chills and fever every 36 to 48 hours that is accompanied by profuse sweating and asks for your help. Consult the Infectious Disease Data Base to solve this problem.
- Using the Heath BIOSOLVE program Toxicology, solve the following scenario: A farm worker is rushed to the emergency room where you are the medical team on duty. The patient shows symptoms of poisoning, included elevated methemoglobin levels and partial paralysis. Consult the Toxicology Data Base to help get answers.
- Using the Heath BIOSOLVE program Internal Medicine, You are a team of physicians in the Peace Corps in Southeast Asia. A woman brings her infant to your office for a checkup. You are immediately struck by the puffiness of the baby's body and the skin lesions you observe. The mother says her baby will not eat. Consult the Internal Medicine Data Base to help resolve this case.
- Using the CD Rom disk A.D.A.M. Essentials, have each subsequent team research a different one of the following list of problems:
Chicken pox virus
Splinter in the finger
Have each team choose one and write a health report to include; how the agent enters the body, how it spreads in the body (and to another person). Describe the body reaction, treatment, and prevention.
- Use the Macintosh program Life & Death from The Software Toolworks, a highly motivating simulation program in which the surgeon and two or three assistants work feverishly to battle the infection which often sets in after their diagnosis and treatment efforts.
Have the teams of students rotate each half hour to the next computer/problem, or (to reduce the time for this activity) have each team give a report to the class concerning what their problem was and how they went about the process of solving it.
Lectin Agglutination Lab
Make a crude extract of a lectin (a glycoprotein found in seeds which acts like an antibody of non-immune system origin). Can use Ulex europeus (Gorse - a very common plant in Scotland).
In a mortar and pestle, grind 10 g of the seeds in 100 ml of 0.9% NaCl solution. Spin down in a centrifuge until pelletized at the bottom of the tube. Aspirate any lipid layer off the top and decant the supernatant into a 250 ml beaker or flask. Add ammonium sulfate to 70% saturation (based upon ammonium sulfate saturation chart). Stir constantly w/magnetic stir bar until (NH4)2SO4 is completely dissolved. Remove stir bar, let sit 24 hrs.; then swirl flask to resuspend the precipitated protein; then spin down in centrifuge at as fast a speed as possible until pelletized. Decant and throw away the supernatant. With a Pasteur pipette, resuspend the pellet in a minimum amount of deionized water and transfer to a dialysis bag. Dialyze several times against a solution of 20mM phosphate buffered saline (PBS) to remove the (NH4)2SO4. After all the ammonium sulfate has been dialyzed out you will have an off-colored clear solution (any "junk" left is denatured protein that didn't re-nature). Spin down and save the supernatant. This can then be frozen (although you will lose some protein each time the lectin solution is frozen). It's better to preserve it with thimersal (from Sigma) and refrigerate. This preparation of lectins can be used to distinguish O blood types from A or B (or even samples of saliva as 78% of the population are "secretors" who give off the recognition molecules in their saliva) since it only recognizes and agglutinates Type O. It specifically recognizes the sugar L-fucose (like it would an antigen) which is the terminal sugar on Type O blood cells. (Type O blood can also be obtained from out-dated blood bank sources) Adding gluteraldehyde - which students cannot be allowed to handle - allows the blood samples to be kept for many years. Use a microtiter plate with 50 ul of 0.9 NaCl solution and 50 ul of blood, or other sample, in each well. Then add 50 ul of lectin to the first well using a micro diluter tu
be (which holds exactly 50 ul in its tip). After spinning the tube in the well, pick up 50 ul of that mixture and place in the next well, again spinning to mix. Repeat this through the series of perhaps 8-10 wells, then set aside and allow agglutination to occur. The end mark is the last well in which agglutination occurred, as noted by the confluent spread of the "locked" cells across the entire bottom of the slightly conical well, as opposed to non-agglutination which will appear as a tiny clump of cells right in the center of the conical well.
WRITTEN ASSIGNMENT (SYNECTICS): Explore the use of metaphor in having students respond to the question -
In what way might the recent emerging viruses from the tropical biosphere (Ebola, Monkeypox, Dengue, Lassa, Rift Valley, HIV, Marburg, Sindbis, the hantaviruses, etc.) be like the EarthÕs immunological response to an extreme amplification of the human species just as the human body mounts a response to invading foreign species?
[from implications suggested by the book The Hot Zone by Richard Preston, Random House, N.Y., 1994]
Possibilities for consideration include:
PROJECT - Have partners or teams of students select one of the following four choices for a project:
- Nearly all these viruses are coming from the declining rain forest biomes, or from the tropical savannah that is being rapidly settled by people. In tropical Africa, source of the scariest of these hypermutating viruses, the recent paving of the Kinshasa Highway (or "AIDS Highway"), bisecting Africa from Congo to Kenya, was followed by the emergence of AIDS and even more lethal viruses.
- Tropical rain forests contain most of the world's plant and animal species. The rainforests, then, are also the largest reservoirs of viruses, since all living things carry viruses.
- Emerging viruses, most of which mutate rapidly, are surfacing from these ecologically damaged regions of the earth, and are finding that the recent extreme amplification of the human race has suddenly produced a very large quantity of meat, which is sitting everywhere in the biosphere and may not be able to defend itself against a life form that might want to consume it.
- Perhaps the earth's immune system has recognized the presence of the human species and is starting to kick in to rid itself of an infection by the human parasite???
- SKIT: RECOGNITION OF SELF vs. NON-SELF. Have pairs of students script a skit (with roles for all the members of class) which will portray the elements of immunological response to a specific situation.
- MULTIMEDIA PRESENTATION: Use HyperCard or HyperStudio to create a multimedia presentation to show the effects of antigen-antibody relationships. Students can work in partners and should have at least 12 cards in their stack. Extra credit will be given if the following are incorporated: Laser disk or CD Rom segments, Quicktime movie clips, scanned in images, etc.
- POETRY OR PROSE: Write a work of poetry or prose (fictional) using metaphor, analogy, or simile to convey an immunological concept. (this should be a major work of at least 5-15 pages in length double spaced)
- MODEL: Build a 2 or 3-dimensional physical model (of non-edible materials) to convey the principles of immunological recognition.
THE BODY'S REACTION TO SERIOUS ATTACK
Sometimes cuts can go 'bad' because microbes get into the blood. The accompanying Student Information Sheet gives details of how the body defends itself against such infections. Read this information then answer the questions below.
- What can you see in the area of an infected cut that tells you the body is trying to deal with infection? [Pus.]
- Which type of blood cell attacks invading bacteria? [White blood cells.]
- How do these blood cells deal with microbes? [They engulf and 'digest' them.]
- Why does pus form in an infected wound? [Pus is a collection of dead white cells, damaged in the fight against infection.]
- Explain the meaning of the following terms:
- antigen; [an antigen is a "foreign body" which is recognized as an invader]
- antibody; [an antibody is a substance which is used to 'label' an antigen so that it can be destroyed by the immune defense system.]
- lymphocyte. [a lymphocyte is a white blood cell which can destroy labeled antigens.]
The body provides ideal conditions for bacteria to grow and multiply. If they were not checked, any invading bacteria could soon multiply to the stage where they interfere with the normal working of the body and cause illness.
The white cells in blood provide one of the body's main defenses against microbes which gain entry.
White cells can filter through the walls of blood vessels into the surrounding tissue, where they surround or 'swallow' the microbes which are then broke up or 'digested'.
White cells are often killed in the process of destroying microbes. Pus contains plasma and dead white cells, so if pus develops in a wound it is evidence that some infection has occurred.
The white cells need to be able to recognize unwanted invasions, so that they only destroy invaders and do not harm substances which are a healthy part of the body.
'Foreign' materials, such as microbes, pollen grains or the toxins (poisons) made by some bacteria, are called antigens. The presence of antigens in the body stimulates special organs in the body (the lymph nodes) to produce special proteins called antibodies. Each type of antigen causes the production of a new antibody.
These antibodies circulate in the blood. When they encounter the particular type of antigen which they have been produced to react with, they join onto the antigen, forming an antigen/antibody complex. These complexes can now be destroyed in one of three ways. In some cases, the complex breaks down, destroying the antigen.
In some cases, the antigen/antibody complex is recognized by the white cells and is engulfed and destroyed by them.
Finally, in some cases, the antibodies cause the antigens to stick together (agglutinate) into clusters which can then be attacked by the white cells.
Use the GSE Biology Test (from California) from 1994 which is a performance assessment tool to determine which potential kidney donor would be the best match; using density, agglutination, and the result of graph analyses of Age, Weight, and Physical Activity to determine whether students have acquired the concept of how the immune system works.