Hematology

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Hematology

• What is Karl Landsteiner credited with
  discovering?

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Blood Composition
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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

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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

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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

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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

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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

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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

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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

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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

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Cell Morphology
Platelet
Lymphocyte
Segmented Neutrophil
rbc
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Composition of Blood Leukocytes

• Types of Leukocytes
• Granulocytes
• Neutrophils
• Eosinophils
• Basophils
• Agranulocytes
• Lymphocytes
• Monocytes

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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

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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 carcinogenic so
  phenolphthalein is used and is known as the
  Kastle-Meyer Color test

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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

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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

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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

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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

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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

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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

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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

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Blood Types ABO

• Controlled by GENETICS!!!!!
• Two Categories
• ABO and Rh

A O
AB BO
AO OO
B
O
A B
A O
AA AB
AB BB
A
AA AO
AO OO
A
B
O
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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

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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

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ABO Blood Types
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Agglutination Reactions
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Anti-A Anti- B Anti-A Anti B
A Yes No Yes
B No Yes Yes
AB Yes Yes Yes
O No No No
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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
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Rh Antigen and Antibody Interaction
Anti- Rh
Rh YES
Rh - NO
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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

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Blood Cell Maturation
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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

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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

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DNA

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

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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, AT, GC

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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

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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

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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

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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

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RFLPs
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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)

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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 PCRd
• Can multiplex a large number of these STRs at
  once
• US uses 13 STRs for tests

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