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Helenlee9999 Helenlee9999
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Posts: 2
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12 years ago
Could anyone have answers following questions?


Positive and Negative Controls
1. Why are there a number of washing steps in serological tests?

2. Describe how you would know that you had a “false positive” result. What does this mean for the rest of your results?

3. Describe how you would know that you had a “false negative” result. What does this mean for the rest of your results?

Direct Fluorescent Antibody Technique
4. Why is this technique a direct method?

5. What is an elementary body?

6. How do elementary bodies look under the fluorescent microscope?

7. What do you think would happen if you did not fix the sample to the slide with 95% ethyl alcohol?

8. Which patient(s) tested positive for Chlamydia?

9. Was there any nonspecific binding for any of the samples? Explain.

Ouchterlony Technique
10. What is a precipitin line?

11. What is the unknown antigen in the simulation?

12. Considering your results, do you think that human serum albumin and bovine serum albumin have epitopes in common? Explain.

13. What is the process resulting in antigen and antibody moving toward each other?

Enzyme-Linked Immunosorbent Assay
14. In the “sandwich” analogy of the direct ELISA, what is the “bread”?

What is the filling?
15. Describe some advantages of using the ELISA technique to process a large number of samples.

16. Which patient(s) were positive for HIV?

17. Describe what would happen if you skipped the step where the developing buffer was added.

Western Blotting Technique
18. The Western blot technique is used as the confirmatory test for a positive ELISA result because it provides better specificity. How does this technique provide better specificity?

19. If a patient tests positive for HIV using the ELISA test but negative using Western blotting, what can you say about the initial ELISA result?

20. Describe the role of the developing buffer in the Western blotting technique.

21. Which patient(s) tested positive for HIV using the Western blotting technique?
 
22. Using the choices listed below, decide which of the criteria apply to the indirect ELISA, which apply to the Western blotting technique, and which apply to both. Use “E” if it applies to ELISA, “W” for Western blotting, and “B” for both.
Criteria:
_____ 1. It tests for the presence of antibodies in the patient sample.
_____ 2. Electrophoresis is used.
_____ 3. Substrates that change from colorless to colored are used.
_____ 4. An enzyme-linked secondary antibody is used.
_____ 5. Antibodies against individual antigens are detected.
_____ 6. The reaction takes place in a well in a microtiter plate.
_____ 7. An antigen-antibody reacton is detected.
_____ 8. An optical density is read to determine whether or not a sample is positive.

I would appreciate so much for any answers.  Waving Hand Sign
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wrote...
Educator
12 years ago
Please show us your work before we can provide help.
Helenlee9999 Author
wrote...
12 years ago
 Grinning Face This is what I found so far.
Thank you.

1.   Why are there a number of washing steps in serological tests?
The are a number of steps needed in order to remove any non specific binding that may have occurred.   

2.   Describe how you would know that you had a “false positive” result. What does this mean for the rest of your results?
A positive result with a negative control indicates a “false positive” and your results are invalidated.   

3.   Describe how you would know that you had a “false negative” result. What does this mean for the rest of your results?
A negative results with a positive control indicates a “false negative” and your results are invalidated.   

Direct Fluorescent Antibody Technique

4.   Why is this technique a direct method?
It is considered a direct method because it involves conjugation of an antibody with fluorescent dye.   

5.   What is an elementary body?
An elementary body is an infectious particle of any of several microorganisms.

6.   How do elementary bodies look under the fluorescent microscope?
Elementary bodies look red, no defined & varied shape with a darker spot on them and some had green spots or blotches on them.

7.   What do you think would happen if you did not fix the sample to the slide with 95% ethyl alcohol?
Since ethyl alcohol’s function is to fix the specimen to the slide, I would say the
specimen would be washed away during the preparation of the slide if ethyl alcohol
was not used.   

8.   Which patient(s) tested positive for Chlamydia?
Patient 2   & patient 4

9.   Was there any nonspecific binding for any of the samples? Explain.
Patient 3 had just a tiny bit of green on it which made me think there was     
nonspecific binding because there were only two so its not negative or positive but
in my opinion human error.   
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