* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download File - Forensic Science
Survey
Document related concepts
Hemolytic-uremic syndrome wikipedia , lookup
Blood sugar level wikipedia , lookup
Blood transfusion wikipedia , lookup
Autotransfusion wikipedia , lookup
Schmerber v. California wikipedia , lookup
Blood donation wikipedia , lookup
Plateletpheresis wikipedia , lookup
Jehovah's Witnesses and blood transfusions wikipedia , lookup
Hemorheology wikipedia , lookup
Men who have sex with men blood donor controversy wikipedia , lookup
Transcript
Forensic Serology I. History – Karl Landsteiner (1901) theorized that all blood wasn’t the same. Realized that transfusions of incompatible blood types caused death due to agglutinization (clumping due to immune response) ABO syp triose 1937 – Rh Factor identified Currently there are more than 100 identified blood factors Idea is that no two people will have the same set of blood factors (except for identical twins) because the factors are genetic. Blood – connective tissue made of plasma (50%) and cells (45%) Plasma is composed of: water, ions, enzymes, proteins (fibrin) Cells – erthyrocytes (red blood cells – contain hemoglobin (transports O2 and CO2.)), Leukocytes (white blood cells – have an immune function),Platelets (responsible for bloods ability to clot.). Serum is blood with the clotting factors removed. II. Quick Genetics background: DNA > Genes > Chromosomes Alleles are alternate forms of a gene Alleles are inherited in pairs because there are two parents that provide half of the DNA Humans have 46 chromosomes – gametes (sex cells (eggs or sperm)) have 23 chromosomes. A Karyotype shows the chromosomes of an individual ( see how the chromosomes occur is pairs) Sex of the individual is determined by the sex chromosomes (Males = XY and Females =XX) Sex of the individual is determines by the father. Paternity testing (Civil Court) o Looks at blood type and other blood antigens o Also use HLA (Human Leukocyte Anitgen) – gives a 90% accuracy o DNA is 99% accurate III. Blood Types ABO system – controlled by the “I” gene, for which there are three different alleles (IA, IB, i) The lower case letter denotes a recessive allele. Blood % Surface Antibodies Can Can give Genotype Type Pop Antigens* ** receive blood to blood from A 42 A Anti B O+A A + AB IA IA, IAi B 12 B Anti A O+B B + AB IB IB, IBi AB 3 A and B None O + AB AB IAIB O 43 None Anti A + O ALL ii Anti B Ag induces IR Anitbody – protein in “antiserum” that destroyes or inactivates a specific Ag. Agglutination – clumping that results when Ab’s react with Ag’s. Type O blood is the universal donor because none of the cells have Ab’s Type AB is the universal recipient because serum have no Ab’s IV. Blood typing Blood typing is done by agglutination o Test the blood with Anti-A and Anti-B serum. Anti-A + blood Anti-B + blood Ag present Blood type + A A + B B + + A and B AB None O ( + = agglutination) Test for the presence of Ab’s using type A and type B red blood cells. A type RBC’s B type RBC’s Ab’s present Blood type + Anti-A B + Anti-B A + + Anti A and Anti B O None AB Rh Factor – (“D” antigen ) o Rh positive o Rh negative ABO type and Rh factor are most important in identifying blood for transfusions. V. Characterizations of Blood Stains Criminalist must answer (when looking at dried blood) o Is it blood? o Is it human blood, if not what species. o If human can it be individualized? Preliminary Color Tests: Benzidine Color test common and easy carcinogenic Phenolphthalein (Kastle-Myer test) common, easy, non-carcinogenic not specific for blood - needs confirmation. Luminol blood and luminol floresce Can spray a large area Very sensitive, can detect blood diluted up to 300,000x Doesn’t interfere with later testing Hemastix o Designed to test for blood and urine o Turns green with mixed with blood Benzidine and Kastle-Myer banned on the fact that blood has hemoglobin (Hb) the test have peroxidase like activity that speeds the oxidation of many organic compounds. So, bloodstain and phenolphthalein and water (deep pink) - on a swab not on the specimen. Takayama & Teichmann tests o Blood and specific chemicals produce chemicals and Hb derivatives o Less sensitive than color tests o Susceptible to interference from contaminants in the stain. Human or Animal? Determining the species orgin. o Use a precipitation test Very sensitive small amount of blood needed diluted or old stains can yield a positive result in a precipitation test. Proceedure: A rabbit is caused to produce antiserum to a particular species, o Draw the human blood inject into a rabbit (the rabbit will produce antibodies against the human antigens remove the serum from the rabbit (this is human antiserum) mix human antiserum with the unidentified blood and if you get a precipitation band (cloudy) the blood is human. Antiserums commercially are available for: dogs, cats deer, cows and many other animals. o Diffusion Test - uses agar to allow Ag and Ab