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Really Strange But Serious Question

  1. May 16, 2005 #1
    really strange but serious question - DiscussAnything.com -
    Address:http://www.discussanything.com/forums/showthread.php?t=75273 Changed:10:18 AM on Monday, May 16, 2005
     
  2. jcsd
  3. May 16, 2005 #2

    Moonbear

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    I'm not sure if you can use urine to in any way identify individuals. There would also be a lot of contamination if it's from a car, so probably not very useful as evidence either, other than to show it was there and the damage caused by it.

    No forensics test is going to identify someone out of thin air though. Fingerprints might be the best bet if the person doing it is already in a fingerprint database (there are a lot of ways to get fingerprints on file aside from a criminal record). If this person has not previously been involved in any crimes or been caught to have any information in a database (such as DNA tests), then unless you have a suspect in mind with whom to compare any collected samples, it's not going to help you find someone unknown.

    I'm guessing this is someone dealing with vandalism (:yuck:). They should call the police and see if they can locate any fingerprints. It's possible the criminal touched the car at some point and that might be the easier way to ID them.
     
  4. May 16, 2005 #3
    I was going to say that the blood in the urine could be used in DNA testing, but I see the point Moonbear brought up, you would have nothing to compare with that DNA.
     
  5. May 16, 2005 #4
    Should I post your anser over there moonbear? Did you have a look at the responses? I think yours would be the only informative one she gets.
     
  6. May 16, 2005 #5

    Moonbear

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    Well, red blood cells don't contain a nucleus, so no DNA there, and there really shouldn't be much blood in urine unless the "perp" has something seriously wrong with them. I'm not sure if there would be a sufficient concentration of cells of any kind in the urine to find them in a sample collected off a surface. There'd probably be far more outside contaminants picked up with it, making it rather difficult if not impossible to sort out the cells of the "perp" from the cells of whatever else is on that car surface (bacteria, bird poop, bug splatters, the owner's sloughed skin cells, pollen, etc.), and things like road salts and oils would probably make it really difficult to clean up the sample. This would be quite different from collecting urine in a sterile container. Maybe if there was an obvious puddle left behind, something could be done with that???
     
  7. May 16, 2005 #6

    Moonbear

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    Zoob, I'll leave it up to your judgement. I looked at that site, and I'm not sure if this is someone who is trying to find out if they can get caught for peeing on someone else's car (maybe this is one of those drunk guys MIH keeps catching peeing on her tires :rofl:), or if this is one of those "I saw it on CSI and wonder if it really works that way" kind of questions.
     
  8. May 16, 2005 #7
    I have a vague recollection of hearing that dogs can tell if humans are sick by odors found in urine (how the researchers determined this, I don't know), perhaps they can track the perp by sniffing the sample and searching for the culprit. (supposedly 300 times more powerful sense of smell than humans, I think.)

    Just a thought.
     
  9. May 16, 2005 #8
    Maybe Tribdog would volunteer.
     
  10. May 16, 2005 #9

    DocToxyn

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    I'll have to aggree with Moonbear on this one. Unless the person has some sort of disease or sickness then the urine should be pretty sterile, thus lacking most ways of identifying anyone. If there were some marker of person X that could be isolated from urine (and I don't recall ever hearing of any that are specific enough) then the next biggest hurdle would be environmental contamination, it would never hold up in court. The effects of evaporation/weathering, collection and contamination would eliminate use of urine as a good indicator of identity.
     
  11. May 16, 2005 #10

    DocToxyn

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    I saw something similar to this as well, probably on the Discovery channel. The dogs were able to "diagnose" someone with melanoma, although they were smelling their skin, not urine.

    There are some metabolic diseases that present themselves in the urine. Maple syrup urine disease stems from a lack of a specific enzyme involved in protein/amino acid degradation leading to the buildup of an isoleucine derivative that makes urine smell sweet, although I guess you don't need to be a dog to sense this. Any disease process that compromises kidney function could potentially result in the elimination of abnormal products in the urine and the dog's sense of smell may be able to distinguish such differences from "normal urine".
     
  12. May 16, 2005 #11

    Evo

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    They also have dogs now that are trained to tell when someone is about to have a seizure.
     
  13. May 16, 2005 #12

    Curious3141

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    Normal urine can still contain white blood cells, more so if it's a contaminated specimen (vaginal or urethral meatus). Wbcs have a nucleus.

    Besides, normal urine always contains sloughed off transitional epithelial cells, which are all nucleated. Centrifugation ("spinning down") will help to concentrate the matter of interest.

    Your point about contamination is a fair one, but it certainly would be possible to purify nucleic acid and sort through the mess in the sample. Don't forget that current forensic experts routinely harvest blood from crime scenes for DNA analysis. Blood that's shed and left ex vivo is an excellent culture medium for environmental bacteria. Yet crime labs don't find it too difficult to analyse blood smears that have been out in the open for a few hours, or even days. I don't think uninfected urine is going to present a huge problem in this respect.

    And you're right that the only practical current use of nucleic acid testing would be in the various DNA fingerprinting methodologies, where one would already have to have a group of suspects handy to test a particular sample against.

    But let's walk a little way along the realm of (current) science fiction here. The Human Genome Project has succeeded in sequencing the entire genome, and a very gross functional mapping has already been done. Who is to say that in a few decades down the line, we wouldn't be able to directly extrapolate defining physical characteristics from the complete genome sequence ? It would involve pretty complex mathematical models, but I daresay we'll be able to do simple things like eye color and gross facial structure prediction in a decade or so. Eventually, everything in the phenotype can theoretically be predicted except something having a profound and unpredictable environmental influence (like digital fingerprints).

    So fast forward 50 years down the road. One could certainly envision a complex (and expensive) analyser that could isolate the predominant human DNA and sequence it, salvaging gaps in sequence from degradation from other strands by a complicated automated algorithm. From the complete sequence, a perfect physical portrait of the subject is generated, and further algorithms can be used to artificially "age" the portrait. In this way, a manhunt can be initiated from a drop of urine.

    The whole process will be neater with better specimens like blood, but I don't think this sort of scenario (with a urine sample) is too far fetched in the next 50 years or so.
     
  14. May 16, 2005 #13

    Monique

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    I was going to say the same, I've looked at urine samples and there are epithelial cells to be found. The problem is that it would be hard to extract such samples from a surface, since the cells are dilute. It is easy with a clean urine sample where simple centrifugation will do. We don't have a DNA database yet, so it would be hard to do anything with the data.

    It is interesting to mention that DNA can be amplified from the DNA of a single cell (used in IVF pre-implantation diagnostics). I've heard that forensic researchers are trying to amplify DNA from cells found in fingerprints. I don't know if they succeeded or ever will, since the cells that are shed are keratinized.
     
  15. May 16, 2005 #14

    Monique

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    I don't really see how pee would be such a big problem though (unless it's inside).. just take the car for a wash. People who key cars are disgusting, the other weekend I had a line fixed that ran all the way from the front of the car to the back including the tail light, deep enough to need sanding down and repainting. Why would someone do that?
     
  16. May 16, 2005 #15

    Moonbear

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    That was my point in distinguishing between a "clean" sample, and one on a surface of a car.

    In a blood sample, you'd get a much higher concentration of cells with just a surface swab than in a urine sample.
     
  17. May 16, 2005 #16
    oh god, Where IS that guy!
     
  18. May 17, 2005 #17
    That's why they had to turn Tribdog loose. He wasn't warning, he was causing.
     
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