Serology ppt

• Plasma--fluid portion of the blood (55%)
• Serum--liquid that separates from the blood when a
clot is formed
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• Cells (45%)
• Erythrocytes--red blood cells; responsible for oxygen
distribution
• Leukocytes--white blood cells; responsible for “cleaning”
the system of foreign invaders
• Thrombocytes--platelets; responsible for blood clotting
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• ABO blood groups--based on having an A, B, both
or none of the factors on the red blood cell
• Rh factor--may be present on the red blood cell;
positive if present and negative if not
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•Antigen--a substance found on a red blood cell
•Antibody--a substance that reacts with an antigen
•Agglutination--clumping of red blood cells; will result if
blood types with different antigens are mixed
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Blood is a slightly alkaline fluid
made up of :
water
cells
enzymes
proteins
and inorganic substances
that circulate throughout the vascular
system carrying nourishment and
transporting oxygen and waste.
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• The most non-fluid portion of
blood consists of red cells which
outnumber . white cells by five
hundred to one.
• While medical scientists are more
interested in white cells, forensic
scientists are more interested in
red cells and secondly with serum.
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With serum, the analyst can determine
the freshness of a blood sample because
serum clots several minutes after
exposure to air (a centrifuge is
necessary to separate clotted material
from the rest of serum).
In serum are also found antibodies,
which have important forensic
implications.
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• The typing of blood, with what is now called the
A-B-O system, was discovered in 1901.
• A few years later, starting around 1937, a series of
antigen-antibody reactions were discovered in
blood, the most common ones being ABH, MN,
Rh, and Gm (over 100 antigens exist).
• Most people are only familiar with the Rh factor,
which is technically the D antigen. There are more
than 256 antigens, and 23 blood group systems
based on association with these antigens.
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O A B AB
43-45% 40-42% 10-12% 3-5%
O+ 39%
O- 6%
A+ 35%
A- 5%
B+ 8%
B- 2%
AB+ 4%
AB- 1%
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1901. Karl landsteiner
• First to identify A-B-O human blood groups
• Nobel prize in 1930 for work
• 1937. Identified Rh factor (+ or -)
Right: Dr. Karl Landsteiner
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Around 1900, Karl Landsteiner discovered that there
are four different kinds of human blood based on
the presence or absence of specific antigens found
on the surface of the red blood cells.
In 1940 Landsteiner and Weiner reported the
discovery of the Rh factor by studying the blood of
the Rhesus monkey. 85% of Caucasians, 94% of
Black Americans and 99% of all Asians are Rh
positive.
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Questions to be answered:
• Is it blood?
• Is it human blood?
• Whose is it?
• Determine blood type, alcohol content, drugs
present
• Determine the method(s) in which blood may have
been deposited
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Presumptive Test for blood
1. Kastle-meyer color test
• Phenolphthalein reacts with
hemoglobin
• Turns pink in presence of blood
• Potato and horseradish also turn pink
What is hemoglobin?
a. Protein
b. transports oxygen in blood stream
c. Responsible for the red coloring of
blood
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• Luminol test--reaction with blood results in the
production of light
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• Reacts with blood to
produce faint blue glow
• Works even better on
old stains
• Can reveal blood stains
diluted by a factor of 10,000
• Drawback: destroys the
properties of blood
Right: blood normally invisible glows
blue in the presence of luminol
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• Microscopic survey
• Precipitin test--blood is injected into a rabbit; antibodies
are formed; rabbit’s blood is extracted as an antiserum; the
antiserum is placed on sample blood. It will react with
human proteins. This test is very sensitive and requires
only a small amount of blood.
• Characteristic Differences
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• Will turn green in the presence of blood and then darken
3. Takayama and teichmann test
• Crystals form when chemicals react with hemoglobin
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Frog Blood
• Larger nucleic red
blood cells
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• Numerous non-nucleic
red blood cells--5 to 6
million per mm3
• Larger but less numerous
white blood cells 5 to
10,000 per mm3
• Tiny, cellular fragments
350 to 500,00 per mm3
called platelets
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• A blood type has antigen A and will agglutinate
with B.
• B blood type has antigen B and will agglutinate
with A.
• AB blood type has antigen A and B and will not
agglutinate with either A or B.
• O blood type has neither antigen A or B and
will agglutinate with either.
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Type Antigen Antibody Can Give
Blood To:
A
A
B
Can Get
Blood From
A, AB O, A
B
B
A
B, AB O , B
AB
A and B
Neither
A nor B
AB
A, B, O, AB
O
Neither
A nor B
A and B
A, B, O, AB
O

REACTION
Anti-A Serum
Agglutination
No agglutination
Agglutination
No agglutination
Anti-B Serum
No agglutination
Agglutination
Agglutination
No agglutination
BLOOD TYPE
Type A
Type B
Type AB
Type O
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A. Type AB can give rise to a O offspring
B. Type O can give blood to O only
C. Type AB can give blood to anyone
D. Type AB negative is the rarest in the US
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A. Type AB can give rise to a O offspring
B. Type O can give blood to O only
C. Type AB can give blood to anyone
D. Type AB negative is the rarest in the US
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Type
O
A
B
AB
Percent
45
39
12
4
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Absorption-elution technique
• Antiserum is placed on the blood stain. Antibodies
combine with the specific antigens.
• Unreacted serum is washed off the bloodstain.
• Stained material is heated to 56 degrees C, breaking
the antibody-antigen bond. This process is known as
elution.
• Known red blood cells are added. Agglutination will
occur if antigens present on the added RBC’s were
also originally on the stained material.
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Enzymes--proteins that speed up or slow down
chemical reactions. Enzymes that exist in different
forms are called polymorphic and can be broken
down into their separate proteins called isoenzymes.
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• Adenosine deaminase AD
• Adenylate kinase AK
• Carbonic anhydrase II CA II
• Erythrocyte acid phosphatase EAP
• Esterase D EsD
• Glucose-6-Phosphate dehydrogenase
G6PD
• Glyoxylase U GLO I
• Group-specific component Ge
• Haptoglobin Hp
• Peptidase A Pep A
• Phosphoglucomutase PGM
• 6-Phosphogluconate dehydrogenase
6PGD
• Transferrin Tf
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PGM--phenotypes
Electrophoresis can separate the protein
components into these 10 iso-enzymes.
-
+
1- 1+ 2- 2+ 2-1- 2+1- 2-1+ 2+1+ 2+2- 1+1-
Three of these are most common PGM 1+, PGM 2-1+ and PGM 2
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EAP--phenotypes
Determined by the intensity of the fluorescence. The
darker the band the more it fluoresced.
B
C
A
A BA B CB C CA
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SCENE PATTERN
RECONSTRUCTION
1. Stain condition
2. Pattern
3. Distribution
4. Location
5. Directionality
LAB RESULTS
RECONSTRUCTION
1. Genetic marker typing
2. Age Determination
3. Source
Determination
4. Race Determination
5. Sex Determination
From “Cracking Cases” by Dr. Henry C. Lee
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A field of forensic study which deals with the physical
properties of blood and and the patterns produced
under different conditions as a result of various
forces being applied to the blood. Blood, as a fluid,
follows the laws of physics. It is not influenced nor
affected by race, gender, or age of the one bleeding.
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• A blood droplet will remain spherical in space until
it drops onto a surface
• Once a blood droplet impacts a surface, a
bloodstain is formed.
• A droplet falling from the same height, hitting the
same surface at the same angle, will produce a stain
with the same basic shape.
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• Is approximately 0.05 cc
• Is not the same for all blood droplets--from 0.03 cc
to 0.15 cc
• Is directly dependent upon the surface or orifice
from which it originates
• The impact area is called the target.
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• Size of the droplet
• Angle of impact
• Velocity at which the blood droplet left the
original surface
• Texture of the target surface
• On clean glass or plastic--droplet will have smooth outside
edges
• On a rough surface--will produce scalloping on the edges
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• The distance between the target surface and the
origin of blood at the time of blood shed
• The point(s) of origin of the blood
• Movement and direction of a person or an
object
• The number of blows, shots, etc. causing the
bloodshed and/or the dispersal of blood.
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• Type and direction of impact that produced the
bloodshed
• The position of the victim and/or object during
bloodshed
• Movement of the victim and/or object after
bloodshed
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• Angle of impact--angle at which blood strikes a target
surface.
• Bloodstain transfer--When a bloody object comes into
contact with a surface and leaves a patterned blood
image on the surface.
• Backspatter--blood that is directed back toward its
source of energy.
• Cast-off--blood that is thrown from an object in
motion
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• Contact stain--general term referring to bloodstains
caused by contact between a wet, blood-bearing surface
and a second surface which may or may not have blood on
it
• Transfer--image is recognizable and may be identifiable
with a particular object
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• Swipe--wet blood is transferred to a surface which
did not first have blood on it
• Wipe--a non-blood bearing object moves through a
wet bloodstain, altering the appearance of the
original stain
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• Directionality--relates to the direction a drop of blood
traveled in space from its point of origin
• Terminal velocity--the greatest speed to which a free
falling drop of blood can accelerate in air. It is
dependent upon the acceleration of gravity and the
friction of the air against the blood--approximately 25:1
feet/second.
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• High velocity--greater than 100 feet per second; gives
a fine mist appearance
• Low velocity--5 feet per second or less
• Medium velocity--5 to 25 feet per second.
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• Terminal Velocity
• Directionality
• Angle of Impact
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The shape of a blood stain:
• Round--if it falls straight down at a 90 degree angle.
• Elliptical--Blood droplet elongates as the angle
decreases from 90 to 0 degrees. The angle can be
determined by the following formula:
width = sine of the impact angle
length
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• The more acute the angle of impact, the more
elongated the stain.
• 90 degree angles are perfectly round with 80 degree
angles taking on a more elliptical shape.
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• At about 30 degrees the stain will begin to produce a
tail.
• The more acute the angle, the easier it is to determine
the direction of travel.
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• The harder and less porous the
surface, the less the blood drop
will break apart.
• The softer and more porous the
surface, the more a blood drop
will break apart.
• The pointed end of the blood
stain faces the direction the
stain is traveling.
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The location of the blood
source can be
determined by drawing
lines the various blood
droplets to the point
where they intersect.
This is the blood’s
origin.
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The area of
convergence is the
point of origin; the
spot where the “blow”
occurred.
It is determined by
drawing a line from the
area of intersection
straight up to where to
where the angle of
impact would intersect
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What evidence
can you see in
this crime
scene? What
story does the
scene tell?
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The dog locates
human scent. A
closer look
shows that the
ashes have
human remains
and clothing.
In addition,
look closely at
the rocks on the
next slide.
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• Class evidence for blood would include blood
type. If you can determine the DNA you would
have individual evidence.
• Blood stain patterns are considered
circumstantial evidence in a court room.
Experts could argue many points including
direction of stains, height of the perpetrator,
position of the victim, left/right hand, whether
the body was moved, etc.
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• Among the smallest and most
highly specialized cells in the
human body.
• Has a head and a tail
• Contains 23 chromosomes with
the genetic material found in
the head
• Males release 2.5 to 6 milliliters
of seminal fluid per ejaculation
with approximately 100 million
sperm per milliliter.
Magnified 400X
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Determination of Seminal Fluid
• Acid phosphatase color test
• the presence of acid phosphatase, the enzyme
secreted by the prostate gland into the seminal fluid,
will turn purple when sodium alpha
naphthylphosphate and Fast Blue B solution are
placed on it.
• It will also fluoresce under UV light when it comes
in contact with 4-methyl umbelliferyl phosphate.
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Determination of Seminal Fluid
• Prostate Specific Antigen (PSA) or p30--unique
to seminal plasma
• P30 is isolated and injected into a rabbit where
antibodies are produced (anti-p30)
• The stain extract is place in one well of an
electrophoresis plate and the anti-p30 in the
opposite well. The electric is applied and the
antigens and antibodies move toward each other.
The formation of a precipitation line between the
wells shows the presence of p30 in the sample stain.
It must be seminal fluid.
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• 80% of people are considered secretors. Their
blood-type antigens are found in high
concentration in their body fluids such as
saliva, semen, vaginal secretions and gastric
juice. If you are a secretor, you will have a
higher concentration of A and B antigens than
does your blood!!
• With the advent of DNA, the secretor evidence
is not as important as it once was.
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• Genotype--letters that represent the traits; ie, AA,
AO, BO, BB, AB and OO
• Phenotype--words that describe the traits
• Heterozygous--different alleles for the same trait;
ie: AO, BO, AB
• Homozygous--the same alleles for the trait; ie: AA,
BB, OO
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