Transcript Diagnostics and Forensic Science

Diagnostics and Forensic
Science
Diagnostics Services
• Diagnosis – determining the cause of an illness or condition
• Clinical Laboratory Scientists or Medical Technologists often do the tests
• Done in hospitals and independent labs; often requires specific
machines
• Reference Range – averaging the test results for large population + 2
S.D; helps define what is in “normal” ranges
Diagnostic Services
• Blood
• Urinalysis
• Culturing
• Biopsy
• Rapid Diagnostic Tests
• Home Medical Test kits
• Imaging
• Genetic Tests
Careers
• Pathologists
• Medical Lab Technologist/Technicians
• Nuclear Lab Technologists
• Phlebotomists
• Radiologists
• Radiology Technologists
Uncertainty of Testing
• Sensitivity – measures how often someone who has the condition
tests positive
• Specificity – measures how often someone who does not have the
condition test negative
Forensics
What is forensic medicine?
• Latin word - forensics
• Means public discussion or debate
• Science used in justice system for legal
purposes
• Facts based on scientific investigation
• Goal is to determine facts and truth
• Uses multiple science specialties
Autopsies
Definition and Purpose
• To see for oneself
• Surgical operation done on a dead body
• To learn about person’s health and cause of
death
Legal Requirements
• Coroner
• Medical examiner
• Pathologist
Autopsies
Reasons for autopsy
• Determine which disease or injury caused
death
• Diagnosis - confirmation and understanding
• Evaluate possible public health issue
Preparation
• If not required by law, permission needed
from next of kin
• Legal consent form
Autopsies
Procedure
• Complete medical history and review of records
• External physical exam
•Body tag
•Weight and height
•Clothing and valuables identified
•Scars, tattoos, injuries, wounds, bruises recorded
•Foreign objects noted
• Photos and x-rays taken, if needed
Autopsies
• Complete internal exam
• Dissection of head and abdomen
• Organs removed, weighed, measured, and
examined
• Tissue samples examined under microscope
• Fluid samples tested for drugs, infection
• After autopsy complete, legal death certificate
Results
• Natural death – disease or old age
• Unnatural death – unnatural, unexpected, or
unusual cases
Autopsies
Methods to determine time of death
• Traditional indicators
• Rigor mortis
Begins three hours after death in face and
eyelid muscles
Takes twelve hours to affect entire body
Process reverses after 36 hours
• Lividity (hypostasis)
Visible 30-60 minutes after death
Red cells settle and skin below turns red
In 6-10 hours, color becomes permanent
Autopsies
• Body temperature
Falls at rate of one degree per hour
Obesity and warm environment slows
cooling
• Forensic Entomology
Involves the life cycle of insects which is
predictable
• None of the above are totally reliable and can
be manipulated
DNA Analysis
• Deoxyribonucleic Acid make of a chain of nucleotides consisting of a
deoxyribose sugar, a phosphate (PO4), and a nitrogenous base (A,T,C,or G)
• Double stranded and helical (twisted) with A’s of one strand pairing with
T’s of the other strand; G and C also pair up complementary.
• 3 billion base pairs in human genome and 21,000 genes
• DNA 95% similar to chimpanzee
• DNA sequence highly conserved among different species
DNA Analysis
• Used to identify people; uses 13 Short Tandem Repeats (STR)
sequences found throughout genome
• Used to identify ancestory and relatedness
• Also used to diagnose probability of having
a genetic disease
• Can be used to access treatment options
• Can be used for newborn screening
DNA Techniques
• Karyotyping – technique to look at an organisms chromosomes;
allows us to determine chromosomal mutations
• Polymerase Chain Reaction – copies DNA molecules in vitro
• Gel Electrophoresis – allows us to cut and and visualize DNA
fragments while studying them.
• Microarrays – allow scientists to study gene expression of 1000s of
genes to determine if they are turned on or off at a particular time;
good for studying cancer.
Forensic Anthropology
Skeletal anatomy
• 206 bones
• Man = 12 pounds
• Woman = 10 pounds
What bones show
• How person lived
• Debilitation illnesses (rickets, polio, healed
fractures)
• Right handed or left handed
• Clues to occupation
Forensic Anthropology
Questions about skeletal remains
• Age of person at time of death
• Sex of person (skull and pelvis)
• Race
• Height
Forensic Odontology
1. Characteristics of teeth after death
a. No other part lasts longer
b. In fires, teeth usually only means to ID remains
c. No two people have identical teeth
2. Requirements for identification
a. Need dental records
b. Dentists chart five surfaces of each tooth in a
grid (odontogram)
c. Can also provide “bite mark” evidence
3. Teeth useful in determining subject’s age
Forensic Toxicology
• Investigate drugs and poisons in the body (hair, blood, urine, etc)
• Use Gas Chromatograph/Mass Spectrometer (GC/MS) to analyze the
components of samples to identify the drug/poison or its metabolites
in the sample
• Can determine amount of substance and whether it could have had
negative impact on victim resulting in death.
• Analytical chemist