BU Forensic Bio

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BU Forensic Bio
2010-04-28 12:20:43
BU Forensic Bio

Urine, Feces, and Vaginal Secretion Identification
Show Answers:

  1. What is the average daily adult output of urine?
    approximately 1500 ml (however, amount of urine produced is a direct result of liquid intake, temperatrue, and physical activity.
  2. What is responsible for the yellow color of urine?
    Urochrome pigment (a compound in urobilin or urbilinogen)
  3. Urine contains approximately how many grams of solids? What are these solids?
    55-70 grams; various crystalline substances and epithelial cells from urinary tract lining
  4. Although urine is a poor source of DNA, it has been reported that there is more DNA-containing cellular material in female urine. Why?
    The theory is that the urine has more contact with epithelial cell surface area in females.
  5. What are the two most abundant constituents of urine?
    • Water (95%)
    • Urea (2%)
  6. The most common chemical tests involving urine identification target what two substances?
    • Urea
    • Creatinine
  7. Since the color of urine is usually masked by the substrate, an ALS is often employed. Under what conditions will urine fluoresce?
    at 450 nm and an orange filter
  8. The characteristic ammonia odor (sniff test) of urine is due to bacterial breakdown of ________.
  9. Urea is found in what five body fluids?
    Urine, semen, saliva, sweat, and serum
  10. In the presence of DMAC and acid, urea will turn _________
  11. Crystals form as a result of urea combined with xanthydrol and acetic acid. What type of method is this (indirect or direct)?
    indirect method
  12. Urea nitrite crystals from when acetone extract of a urine stain is followed by conversion to urea nitrate. What type of method is this (direct or indirect)?
    Direct Method.
  13. In the presence of the enzyme urease, urea is hydrolyzed to _______ and ________.
    Urea + H2O yields _______ + _______
    Urea + H2O yields CO2 +2NH3 (carbon dioxide and ammonia)
  14. What are the two types of chemical tests that target urea?
    • DMAC and acid (turns urea pink/red)
    • radial diffusion gel using bromothymol blue (BMB) and urease
  15. Using a radial diffusion gel with BTB and urease, a dark circle appears around the well when ___________ reacts with BTB
    ammonia. (the urease will react with the urea in the urine and convert it to carbon dioxide and ammonia)
  16. In what four body fluids is creatinine found?
    urine, sweat, saliva, semen
  17. what is the daily output of creatinine?
    approximately 1 to 1.8 g/day
  18. creatinine is usually produced at a fairly constant rate, and is the breakdown of _________ ________ in muscle.
    creatine phosphate
  19. Creatinine reacts with picric acid in alkaline envrionment to form bright orange/red product creatinine picrate. What is this test called?
    Jaffe test.
  20. Urea and Creatinine are waste products found in urine. But what is the most abundant protein found in urine?
    THG (Tamm Horsfall glycoprotein)
  21. How can THG be detected in urine?
    Electrophoresis or other immunoassays.
  22. Feces have a characteristic odor due to the break down of amino acids into ___________, _________, and methyl-mercaptan by bacteria.
    skatole, indole
  23. the brown color of feces is due to ___________, a breakdown product of __________.
    stercobilin (urobilin); hemoglobin
  24. Feces is mostly made up of __________.
    water (about 75%).
  25. chemical screening of feces depends on microscopic features and the detection of __________, a bile pigment precursor excreted in feces.
  26. bacteria comprise approximately __________ of the dry weight of feces.
  27. What is the best identification technique for feces?
    Microscopic examination.
  28. Undigested food residue can be seen in feces that was ingested ____ to ____ hours previously.
    12 to 24 hours.
  29. What enzyme found in feces could be used for detection?
  30. There are two color tests for feces.
    Bilirubin is oxidized to ________ color with HgCl2.
    Urobilinogen will fluoresce _______________ with HgCl2, ZnCl2, and UV light
    • bilirubin will become pink-red
    • urobilinogen will fluoresce apple green (however, may not be present in young infants)
  31. DNA testing on fecal material is usually unsuccessful. What are the two possible reasons for this?
    • 1) due to inhibitory effects of bile pigments
    • 2) large amounts of bacteria and digestive enzymes may also be a factor

    (as a side, mDNA testing on fecal matter has been shown to be more successful)
  32. What is the most forensically important component of vaginal secretions?
    epithelial cells (as a source of DNA)
  33. There are 8 constituents commonly found on a vaginal swab. What are they? (hint: The first letters of each are in these words: BEEP CUBY)
    • Bacteria
    • Epithelial Cells
    • Enzyme
    • Proteins
    • Cervical mucus
    • Urine
    • Blood
    • Yeast
  34. What types of cells are the largest seen on a vaginal smear? Basal, Parabasal, Intermediate or Superficial
  35. There are 4 characteristics that describe superficial cells. What are they?
    • polygonal in shape
    • distinctly flat
    • nuclei absent or small and dark
    • closest to body surface
  36. What is the only difference between Vaginal Acid Phosphatase (VAP) and SAP?
    elecrophoretic mobility
  37. Glycogen is found, on average, in approximately what percentage of vaginal cells?
  38. When stained with iodine, what color does glycogen become?
  39. Since glycogen is estrogen-controlled, during what two periods of a female's life is glycogen present in vaginal epithelium?
    Childbearing years and in newborns (controlled by mother's hormones)
  40. What type of staining is used for glycogen identification in which cells without glycogen turn golden yellow and cells with glycogen stain chocolate brown?
    Lugol's Iodine
  41. What are two commonly used staining techniques for identifiying vaginal epithelial cells?
    • PAS (Periodical Acid Schiff)
    • Lugol's Iodine
  42. What type of staining technique turns the glycogen in vaginal cells a magenta color?
    PAS (periodic acid schiff)
  43. What are some disadvantages of glycogen staining to determine the presence of vaginal cells (there are four given)?
    • 1. the end of the urethral canal in the penis also contains glycogenated e-cells
    • 2. low concentration of glycogen in mouth (less than 1% of cells)
    • 3. anal/rectal area may contain some glycogenated cells, but stains from these areas often contain fecal material, which may help distinguish them.
    • 4. the prescence/amount of glycogenated cells is variable depending on the stage of the estrous cycle.