other biological fluids, tissues, and touch dna Flashcards
(41 cards)
bite marks and saliva
comparison of bite mark and suspect’s dentition photographs
plane parallel using a L scale
perimortem/ potmortem tend to be better defined
collect sample (swab) for dna anlaysis
bite mark analysis is considered subjective to the person evaluating the evidence
innocence project states there is no real scientific support of research into the accuracy or reliability of bite mark evidence
many convictions from bite mark evidence have happened in the past and now the suspects are being exonerated through IP
other GI tract evidence
stomach contents
vomitus
both not a good source for dna
stomach contents
gross and microscopic examination
set time of death
provides investigative leads
where did the deceased last eat
vomitus
microscopic and biochemical analysis
pepsin-proteolytic enzyme
HCl secretion of the stomach has pH 0.8
sexual fetishes
intestine length is very very long
human fecal matter
avg 60-250 grams feces are eliminated dialy
feces produced from an avg diet is 75 % water and 25% solid material
30% of solid material is bacteria
estimated 10^11 bacteria cells per gram of feces in sigmoid colon
identify fecal matter by
odor-skatole and indole
color stercobilin(brown) (bilirubin metabolite (orange and yellow))
one end product of heme catabolism, breaks down hemoglobin
bilirubin
orange-yellow pigment formed in the liver by the breakdown of hemoglobin and excreted in bile
present in fecal material
animal cells - meat
plant cells
epithelial cells
bacteria
identification of fecal matter
fluorescent test
urobilin/urobilinogen
microscopic analysis bacteria, dietary plant material, GI epithelial cells, parasites, etc
green bean dog bones
digested green beans only could be present in fecal material
biochemical analysis
pancreatic amylase, IgA, alkaline phosphatase
Gastrointestinal GI tract
epithelium is renewed every 2-6 days
GI organs have diff turnover rates
estimated 17 billion cells are shed daily from the human small intestine
columnar cell
responsible for absorption of metabolites
goblet cell
protection and lubrication of intestinal lining
both types of cells are epithelial
cuboidal epithelial cells
DNA analysis
analytical difficulties with human feces
degradation of human cells and dna
bacteria
innate PCR inhibitory substances
will block per amplification
plant polysaccharides
bile acids, salts , cholesterol
solution
qiagen qiamp stool mini kit
preferential lysis of human cells over bacterial cells using room temp digest
proprietary organic metric
inhibit ex bugger which is specially formulated to separate inhibitory substances from dna
isolation of dna achieved by a silica Gell membrane and spin column
urine identification
locating stain
use ALS, will fluoresce
microscopic analysis of urinary sediment
three components of urine
urea, creatine, Tamm-horsfall urinary glycoprotein
urea
largest constituent of urine
microscopic crystal test
color test, DMAC (o-dimethylamino cinnamaldehyde)
non-specific, cross reacts with sweat
GC-MS
creatine
color test
GCMS
Abacus diagnostics uritrace test, reacts with creatine
Tamm-horsfall urinary glycoprotein
most abundant urinary protein in mammals
immunological assays: RIA, ELISA, CIE, Ouchterlony
CIE (crossover immunoelectrophoresis)
RSID
urinary sediment
kidney - cuboidal cells
bladder - transitional cells, often binucleated
urethra - columnar cells, squamous at glans pens
vaginal contamination - squamous cells
spermatozoa
urniary casts - result of solidification of material (protein) in the lumen of the kidney tubules, specifically the nephron, and eliminated via the urine
individualization of urine
very variable
like the amount of saliva between people and days
skin
most important role is to protect the body from the environment
3 main layers
epidermis
dermis
subcutaneous fat
human skin
glabrous - thick skin
palms of hand, soles of feet
hair free
still has pores and sebaceous glands
thicker than hair skin
non-glabrous - normal skin
90% of body
contains hair follicles that produce hair
epidermis
5 sublayers, continuously rebuild skin
stratum corneum
a layer of dead flattened enucleated cells filled with the protein keratin
stratum lucidum
the nuclei and other cell organelles disintegrate as the cell dies
stratum granulosum
keratinocytes migrating from underlying stratum spinous
transfer of melanin granules to cells
stratum spinous
keratinocytes (mature basal cells)
produce keratin
contains immune cells called langerhan’s cell
stratum basale
deepest layer of epidermis
contains continually dividing basal cells
melanocytes (color) found between basal cells
losing nucleus, gaining keratin from basale to corneum
epidermis
30-45 days time it takes for basal cells to mature and migrate to top of the epidermis
avascular
cells at surface are continuously shed
millions of cells lost daily
over 8 pounds shed yearly
contributes to household dust
dermis
true skin
highly vascular
hair follicles
sweat and sebaceous glands
collagen fibers for elasticity
dermal papillae
projections of dermis into overlying epidermis
brings dna closer to surface, glands do the same
sebaceous - oily, stinky
swear - more watery
sweat glands
ducts of sweat glands course through the inter papillary pegs to the surface of the skin
inter papillary pegs
wehre epidermis is much thinner
brings dna closer to surface
dna within seat
epidermis also sheds dna with sweat
touch dna
located exchange principle
every contact leaves a trace
generally understood as with contact between two items, there will be an exchange
oily hair dna from oil from sebaceous glands
touching face eyes nose a lot
more dna on hands
if the top layer of skin doesn’t have nuclei how can we find touch dna
nucleated cells, dna are shed through sweat and sebaceous glands
there could be short pieces of free dna present that in totality create a profile
from process of shedding
dna could be transferred from other areas of the body
like from saliva
