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Hematology

Hematology. What is Karl Landsteiner credited with discovering?. Blood Composition. Key Terms . Anticoagulant : an agent that prevents the clotting of blood. Examples are EDTA, Citrate and Heparin Capillary : small blood vessel that connects arterioles and venules

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Hematology

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  1. Hematology What is Karl Landsteiner credited with discovering?

  2. Blood Composition

  3. Key Terms • Anticoagulant: an agent that prevents the clotting of blood. • Examples are EDTA, Citrate and Heparin • Capillary: small blood vessel that connects arterioles and venules • Hematoma: a subcutaneous mass of blood at a venipuncture site

  4. Key Terms • Hemoglobin: the oxygen carrying molecule of red blood cells • Hemolysis: the breakdown of red blood cells, with the release of hemoglobin into the plasma or serum. Cannot use hemolyzed samples in lab tests • Icteric: jaundiced; dark yellow or greenish serum or plasma

  5. Key Terms • Lipemic: having abnormally high level of fat. Milky looking samples • Plasma: pale yellow part of whole blood; contains all clotting factors • Serum: liquid portion of blood without the protein fibrinogen, which is one of the clotting factors; clot removed

  6. Key Terms • Agglutination: the clumping together of rbc by the action of an antibody • When A cells are added to a blood sample, agglutination will occur only in the presence of anti-A • Serology: the study of antigen – antibody reactions using laboratory tests

  7. Function of Blood • Transporting fluids such as: • Nutrients from digestive tract • O2 from lungs • Waste from cells • Hormones • Aids in heat distribution • Regulates acid-base balance

  8. Composition of Blood • Plasma: liquid portion of blood w/out cells • Contains all of the following • Water Nutrients • Electrolytes Metabolic waste product • Hormones Vitamins and enzymes • Plasma proteins such as fibrinogen, albumin and globulin

  9. Composition of Blood: Erythrocytes • Red blood cells are responsible for: • Transport of oxygen and nutrients • Removal of waste and CO2 from the cells • Distribution of heat • Hemoglobin: the O2 carrying potential

  10. Composition of Blood: Leukocytes • WBC are responsible for: • Phagocytosis – to engulf and absorb waste material and harmful microorganisms in the blood stream and tissues • Synthesis of antibody molecules • Inflammation process • Production of heparin – component found in lung and liver tissue which have the ability to prevent clotting of blood. • Heparin used in the treatment of thrombosis

  11. Cell Morphology Platelet Lymphocyte Segmented Neutrophil rbc

  12. Composition of Blood: Leukocytes • Types of Leukocytes • Granulocytes • Neutrophils • Eosinophils • Basophils • Agranulocytes • Lymphocytes • Monocytes

  13. Composition of Blood: Thrombocytes • Platelets – the smallest of the solid components of the blood • Responsible for the clotting process • Coagulation: term for clotting • Embolism: a blood clot which is moving through the body

  14. Forensic Characterization of Blood • 1st questions a criminalist has to answer is: • Is it blood • If yes, is it human • If yes, can it be associated w/ a particular person • Preliminary color test for blood is the Benzidine color test but this is carcinogenicso phenolphthalein is used and is known as the Kastle-Meyer Color test

  15. Forensic Characterization of Blood • Hemoglobin possesses peroxidase like activity which when mixed with phenolphthalein and hydrogen peroxide it will cause the formation of a deep pink color • Kastle-Meyer is not specific for blood as some vegetables such as potatoes and horseradish contain peroxidase and can react; however they should not be common at a crime scene so it is often considered a good indicator

  16. Forensic Characterization of Blood • Hemastix strips can also be used to detect the presence of blood • Luminol test is another presumptive test for blood which produces light rather than a color reaction. Objects being tested must be in a dark location to view the luminescence (emission of light). • Extremely sensitive and can detect blood diluted up to 300,000 times • Luminol will not interfere with other DNA testing

  17. Forensic Characterization of Blood • Once blood is found it must be determined to be human • Precipitin test is the standard test • Reagents are available to determine if blood is dog, cat or deer • A positive test is a cloudy ring or band at the point where the two liquids meet • Only a small amount of sample is required • Precipitin test is very sensitive and can test positive on a sample as old as 10 years • Extracted tissue samples from mummies as old as 4,000 years have tested positive

  18. Forensic Characterization of Blood • Gel diffusion is another method which can be used. • Antigen and antibody assay • Gel electrophoresis can also be used to determine if a sample is human blood or not • Antigen and antibody assay • Uses electrical current and ppt. line forms where the two samples meet if it is a positive reaction

  19. Blood Types • Four Major Groups • A B AB O • Blood types are inherited from your parents • Antigen is present on the red blood cell; typing is done w/rbc • Antibody is present in the plasma; antibody screening done on plasma

  20. Blood Types • O negative • Universal donor • It carries no antigen • AB positive • Universal recipient • It carries no antibodies in the plasma • 43% of population are O, 42% A, 12% B and 3% AB

  21. Rh Factor (D antigen): found on the surface of rbc • Rhesus factor: discovered in rhesus monkeys in 1937 • Can be phenotypically positive or negative • Positive is dominant over negative • If positive is present, then you will express positive phenotype + - + - _ _ + +

  22. Blood Types: ABO • Controlled by GENETICS!!!!! • Two Categories • ABO and Rh A O B O A B A O A A B O

  23. Blood Types: What Ag do they have? • A positive blood has which Ag present on rbc? • A antigen and Rh antigen • B negative blood has which Ag present on rbc? • B antigen • AB + blood type has which Ag present? • Both A and B Ag and Rh antigen on the rbc

  24. Who can donate to whom? • A + donor: what blood types can this pt. receive? • A+, A-, O+, O- • Your blood type is B-, what blood types can donate to you? • B- and O- AB- as a last resort

  25. ABO Blood Types

  26. Agglutination Reactions

  27. Examples of ABO blood typing O negative carries no Ag and therefore does not react with any Anti A, B, AB Pos reaction Neg reaction

  28. Rh Antigen and Antibody Interaction

  29. Normal Ranges • RBC: female 3.6-5.0x106mm3 male 4.2-5.4x106mm3 • WBC: 4.5-10.5x103mm3 (African Americans is sltly lower 3.2 is still normal) • HCT: female 36-48%male 42-52% • Hgb: female 12-16 g/dL male 14-17.4 g/dL • Platelets: 140-400x103mm3

  30. Blood Cell Maturation

  31. Blood Splatter Analysis • Location, distribution, and appearance of blood stains are an important part of forensics • Investigators try to determine: • Direction • Dropping distance • Angle of impact • Splatter analysis is often used for crime scene reconstruction

  32. Blood Splatter Analysis • Factors which influence stain patterns are: • Surface texture • Direction of travel • Pointed end of bloodstain always faces its direction of travel • Angle of impact is determined by measuring the degree of circular distortion of the stain • Blood striking a surface at right angles gives rise to a nearly circular stain • As the angle decreases, the stain becomes elongated in shape

  33. DNA • DeoxyriboNucleic Acid • Found in the nucleus • 46 chromosomes • 25,000 genes • Structure determined by Crick and Watson • DNA fingerprinting by Alec Jeffreys

  34. Structure of DNA • A polymer made of repeating nucleotides • Nucleotide consists of a deoxyribose sugar, a phosphate, and a nitrogen base (Adenine, Thymine, Cytosine, or Guanine) • Double stranded, helical • Complementary base pairing, A=T, G=C

  35. DNA at Work • DNA in nucleus is copied into a strand of RNA (transcription) • RNA is read at the ribosome to make assemble amino acids into proteins (translation) • Every 3 bases on DNA codes for a different amino acid

  36. Replication of DNA • Replication – the synthesis of new DNA from existing DNA in the nucleus • DNA polymerase assembles new DNA strand and proof- reads it • Replication occurs in nucleus prior to cell division

  37. Polymerase Chain Reaction • A technique for replication, or amplifying, a portion of DNA outside the cell • Each cycle doubles the number of copies • 1 1x107 in 30 cycles

  38. DNA Typing with Tandem Repeats • Region of chromosome that contains multiple copies of a core DNA sequence arranging in a repeating fashion between the coding regions (genes) • Restriction Fragment Length Polymorphisms used enzymes to cut the DNA around these tandem repeat sites and then run them on a gel electrophoresis • A Southern blot was then performed and radioactive probes were hybridized to help visualize the RFLPs

  39. RFLPs

  40. PCR PCR has the following advantages: 1. PCR can use shorter sequences 2. shorter pieces more stable 3. smaller amounts of DNA can be used (10-9 gram)

  41. Short Tandem Repeats (STRs) • A region of a DNA molecule that contains short segments of 3-7 repeating base pairs. • Generally less than 450 bp long • Less degradation • Can be PCR’d • Can multiplex a large number of these STRs at once • US uses 13 STRs for tests

  42. Capillary electrophoresis • Sex Identification by focusing on the amelogenin gene

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