1 / 16

Forensic Serology

Forensic Serology. Chapter 8. Blood Components. Plasma--fluid part of blood unclotted blood Erythrocytes—hold hemoglobin and transport oxygen Leukocytes—immune cells Platelets--clotting

baylee
Download Presentation

Forensic Serology

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Forensic Serology Chapter 8

  2. Blood Components • Plasma--fluid part of blood unclotted blood • Erythrocytes—hold hemoglobin and transport oxygen • Leukocytes—immune cells • Platelets--clotting • Serum—yellow fluid that remains after clotting of blood, mostly water + dissolved substances (proteins, ions, etc)

  3. Antigen and Antibodies • Blood Type A has A antigens and B antibodies • Blood Type B has B antigens and A antibodies • Blood Type AB has both A and B antigens and no antibodies • Blood Type O does not have any antigens but both A and B antibodies • Positive blood has Rh(D) antigens = Rh+ • Negative blood does not have Rh(D) antigens but has D antibodies = Rh-

  4. Serology • Positive blood will agglutinate with Anti D serum • Negative blood will not agglutinate with Anti D serum • A blood will agglutinate with Anti A serum • B blood will agglutinate with Anti B serum • AB blood will agglutinate with both anti A and anti B serum • O blood will not agglutinate with anti A or anti B • http://www.youtube.com/watch?v=E0d5Qx42vmQ

  5. Paternity Testing with Blood Type • A Blood Type—AA or AO • B Blood Type—BB or BO • O Blood Type—OO • AB Blood Type—AB • Parent gives each offspring one of two alleles

  6. Immunoassay techniques • Used to detect drugs in blood and urine • Animals are injected with proteins with drug antigens—animal makes drug detecting antibodies that can be harvested • Presumptive drug testing with these cultured antibodies can be used to detect opiates, cannabinoids, cocaine, amphetamines, phencyclidine, barbituates and methodone

  7. Producing Antibodies • Radioimmunoassay (RIA)—uses radioactive tags to find drugs • Enzyme-Multiplied Immunoassay Technique (EMIT)—fast and used with urine; adds antibodies to urine that bind to specific drugs • Polyclonal and Monoclonal Antibodies—animals produce many different antibodies when exposed is polyclonal; scientists need one kind of antibody (monoclonal; fused with cancer cell to make hybridoma cell

  8. Blood Stain Analysis • 3 Questions • Is it blood? • Is it human? • Can it be matched closely to a particular person?

  9. Presumptive Color Testing • Benzadine color test—use has been reduced because it is a carcinogen; measures for presence of hemoglobin • Kastle-Mayer—uses phenolphthalein as an indicator, and hydrogen peroxide to cause the conversion of catalase to give pink color; will test positive with samples with catalase (animal and some plant material) • http://www.youtube.com/watch?v=6Ex0Fd_PDhU

  10. Luminol • Presumptive blood test • Reaction with blood emits light that can be seen in darkened area • Sprayed on area, turn dark, emits blue light • http://www.youtube.com/watch?v=hbEHvRrfqrc

  11. Microcrystalline Tests • Takayama test • Teichmann tests • Add chemicals to blood that causes hemoglobin-containing crystals to form • Susceptible to contaminants and less sensitive that color tests

  12. Precipitin Test • Used to determine if blood stain is human or from animal • Grow antibodies to human blood in rabbit; use antibodies to test for presence of human antigens; Human antiserum • Rabbits can be used to make antibodies against various animal bloods as well

  13. Gel Diffusion • Use agar gel—antibodies and antigens come together in medium plate • Blood and human antiserum are loaded into wells • Precipitant forms if blood is human between two wells

  14. Blood Spatter • Important Blood Qualities to Interpret Blood Spatter • Surface texture—more spatter with softer, porous material • Direction of travel—pointed end faces direction of travel • Impact angle—right angle yields circular stain • Origin of spatter—draw lines through many spatter points; point of intersection is origin of spatter • http://www.youtube.com/watch?v=Od8YuwUT794

  15. Forensic Analysis of Semen • Tests for Presence of Semen • Acid Phosphatase Stain—acid phosphatase is made by the prostate gland and added to semen during ejaculation; presence can be detected by acidic sodium alpha napthylphosphate and fast blue dye or 4-methyl umbelliferyl phosphate (will fluoresce) • Microscopic examination—look for presence of sperm cells • Prostate specific antigen—polyclonal antibodies grown in rabbits used to bind to p30 protein or prostate specific antigen

  16. Rape Evidence Collection • Rape Kit Collection from victims • Hair samples: head, pubic, body • Body opening swabs: vagina, anus, mouth • Blood sample • Fingernail scrapings • All clothing • Urine sample • Collected from male suspects • All clothing • Hair: head, pubic, and body • Genital swab • Blood sample • Cheek cells

More Related