Oral Boards 2- Adfs

Front 1

What is backspatter? When is it seen?

Back 1

-blood that's directed back toward the surface of energy (the weapon)

-seen with high-velocity impact injuries

-gunshot wound: may be back spatter from the entrance wound relative to the position of the victim and time of discharge of firearm

-may be deposited on exposed hand, shirt cuff, or arm of assailant holding the weapon if it's discharged at close range

Front 2

Three characteristics of a cast off bloodstain pattern?

Back 2

1. Arc of back swing: blood cast from the arc of the back swing may strike a target surface and produce circular stains at 90 degrees such as an overhead ceiling or nearby wall

2.Continuation of back swing: remainder of blood to be cast off at a greater distance will produce more oval shaped stains due to angular impact (4-8 mm)

3. Patterns are often seen as uniformly distributed trails on the impacting surface with the more elongated stains most distant from the source

Front 3

Examples of weapons that may produce high impact spatter? Traveling velocity? Size of stains?

Back 3

-objects traveling greater than 30 m/s

-rifles and other GSW, industrial machinery

-stains are usually smaller than 1mm in diameter

-forward and back spatter

-fine spray of tiny droplets

Front 4

Examples of medium force bloodstain patterns?

Back 4

-impact spatter

-cast off

-voids

-similar patterns

Front 5

Examples of when you wouldn't expect to see any impact spatter?

Back 5

-direct contact: transferred blood, smeared blood, absorbed blood, running blood, pooled blood

Front 6

Difference between splashed and projected blood?

Back 6

-splashed: large central area; blood quantity greater than 0.1mL; minor or low velocity impact, produced by movement of victim or assailant in blood; also produced by large volumes of blood falling from source

-projected: quantity of blood greater than 0.1 mL acted upon by force other than low velocity impact; pressure present; numerous, spine-like projections with narrow streaking of 2 degree spatter (ex. Arterial gushing, or vomiting)

Front 7

How is angle of impact calculated?

Back 7

-greater the angle, the more spherical the droplet

i=sin-1(w/l)

Front 8

Can you determine the height a particular dripped pattern originated from based on its size and shape?

Back 8

-there is little change in the diameter beyond 7-8 feet

BUT, in general, the higher the height, the larger the diameter of dripped pattern (up to 7-8 feet)

Front 9

What can cause a luminol false positive?

Back 9

-metallic pigments in paint

-metal halide

-bleaches/related compounds

-plant peroxidases

Front 10

Will visible blood also react with luminol, why or why not?

Back 10

-YES, because visible blood will contain iron from hemoglobin which will react with luminol reagent

-not very practical to use on visible blood since you can just see it and collect it

Front 11

Limitations of luminol

Back 11

*interpretation must be conservative

-large pattern recognition NOT small stain: NOT used for spatter

-substrate considerations

Front 12

Basic principle behind luminol?

Back 12

-alkaline solution: sodium carbonate + sodium perborate + dH20

-should be performed in near darkness

-reagents need to be stored away from light

-luminol positive: positive catalyst (iron in hemoglobin)= light(chemiluminescence)

Front 13

When would you use luminol reagent? Why?

Back 13

-detecting traces of blood not seen by naked eye (but ALWAYS look for visible stains first)

-luminol= last thing done at science-need to be confident that there's been an attempt to conceal= MUST have search warrant

-need to overcome burden of intent (it's the difference b/w 1st and 2nd degree murder)

Front 14

How are 3D points of convergence calculated/determined?

Back 14

-use 2D graphical info

-strings are taped to the target surface extending through the long axis of the individual bloodstains

Front 15

What's a point of convergence? How's it determined?

Back 15

-common point to which individual bloodstains can be traced

-determined by tracing the long axis of well-defined bloodstains within the pattern back to a common point or course on a surface

Front 16

Example of low impact spatter pattern? Velocity of travel?

Back 16

-dripped blood

-droplets ~4 to 8 mm in diameter

-occurs after victim is injured; not during infliction of injury

-force of impact 1.5 m/s or less

-i.e. stabbed then walks around bleeding

Front 17

Example of medium velocity spatter? Velocity of travel?

Back 17

-traveling 1.5 to 30 m/s

-droplets ~1 to 4 mm in diameter

-beating with blunt object/stabbing/cutting/blunt force trauma

-possible projected blood

Front 18

Color photo procedure for Luminol

Back 18

-orient camera to field of interest

-maximize frame of content (fill the frame)

-darken area of interest

-open shutter as luminescence begins

-expose film 30-60 seconds

-as luminescence dims... bounce light prior to releasing shutter

-release shutter

Front 19

Photographic settings for luminol

Back 19

-camera mounted on tripod-film speed ASA 200-f-stop open to widest aperture (quantitative measurement of lens speed)--> larger the f-stop, the smaller the aperture width-shutter speed set to bulb-cable release attached, "soft" light source ready

Front 20

Why do we see a pink band at the test area and hot pink in the sample area of a HemaTrace test?

Back 20

-because in sample area there is free floating antibodies

-in test area the antibody-antigen-antibody is lined up in the test area--> easier to see the pink dye because of congregation of dye marked antibody

Front 21

Why is the test area before the control area on Hematrace and p30 tests?

Back 21

-if the control area is last, and the line forms, then we know that if the antigen was present, it would have bound to the test area

-if control area was first, and there was no line formed at the test area, we can't be sure that binding didn't occur because antigen (hemoglobin or PSA) not present or because the test membrane wasn't working

Front 22

Definition of reduction and oxidation?

Back 22

-oxidation: loss of electron or an increase in oxidation state

-reduction: gain of an electron or a decrease in oxidation state (loss of an oxygen)

Front 23

In hematrace and p30 tests, what does

A. positive, B. Negative, and C. Error look like?

Back 23

A. control & test bands

B. control band only

C. no control band (must do new test)

Front 24

False positive during presumptive testing of blood?

Back 24

-plant peroxidases

-fruits, veggies (vegetable peroxidases)

-chemical oxidants (b/c they possess peroxidase activity)

Front 25

Formed elements of blood and their components?

Back 25

1. erythrocytes: RBC: oxygen transport

2. leukocytes: WBC: produce antibodies (protection)

3. thrombocytes: produce platelets: functions in clotting mechanism

Front 26

What is the High Dose Hook Effect?

Back 26

-false negative

-occurs when concentration of human Hb in sample is far above optimal level

-when the sample is carried to sample pad, there are more human Hb molecules than antibodies, and a large amount of human Hb is left unbound in buffer--> binds most antibody in test area, so no room for antigen-human Hb to bind--> weak or no line in test area

Front 27

Do RBS have nDNA?

Back 27

-immature RBCs have a nucleus and therefore nDNA (found in bone marrow)

-mature RBCs do not have a nucleus and therefore no nDNA

Front 28

Principle behind presumptive blood tests?

Back 28

-depend on peroxidase-like activity of hemoglobin

-presumptive positive for blood= color change

(blue/green= TMB)

(pink= phenolphthalein)

Front 29

Describe TMB test

Back 29

TMB= chromagen, H2O2= oxidizing agent

TMB is oxidized by hydrogen peroxide(NH2 area oxidized), and hemoglobin is the catalyst for reaction

wait 5 seconds for color change

Front 30

Draw the chemical reaction for TMB test

Back 30

Front 31

Difference between Benzidine and TMB?

Back 31

-same color reaction

-benzidine is more sensitive, but is a carcinogen

-TMB is the safer alternative

Front 32

would presumptive blood tests still function properly if peroxide was added 1st and TMB 2nd?

Back 32

-if color change after just TMB= could mean peroxidase activity in sample

-by adding hydrogen peroxide before TMB, and color change= same color results BUT no way to tell if Hb is present or another substance present with peroxidase acitivity

Front 33

Function of blood? Which components are used for DNA analysis?

Back 33

1. transport- RBC carry oxygen

2. regulation- pH balance

3. protection- WBC (phagocytosis, antibody activity)

4. clotting mechanism (activation to fibrin formation= thrombocytes

*RBC have no nucleus, so WBC are used for DNA analysis

Front 34

Conjugate pad (sample area) of Hematrace contains what?

Back 34

-dye marked monoclonal antihuman hemoglobin antibodies (mobile)= Ab*

-sample enters-->buffer dissolves the antibodies-->hHb binds with antibodies= Ab*-hHb

Front 35

Dilution limit of presumptive blood tests?

Compare to other blood tests?

Back 35

-Based on training: TMB= 1:10,000 and Phenolphthalein= 1:10

-TMB more sensitive than phenolphthalein, o-toluidine, and leucomalachite green

-phenolphthalein is more specific than TMB

-benzidine is most sensitive, but carcinogen

Front 36

Approximate pH of blood?

Back 36

~7.35 to 7.45

Front 37

What does it mean to have peroxidase like activity?

Back 37

-it's not the actual enzyme peroxidase, but has functions similar to it

-Heme has this activity and will catalyze the oxidation of substrate in the presence of hydrogen peroxide

-TMB provides reduct substrate upon which heme can carry out its peroxidase-like activity on

Front 38

Test area of hematrace contains what?

Back 38

-immobilized, polyclonal anti-hHb antibody

-captures dye marked Ab*-Ag complex out of buffer flow--> dye band forms with hHb concentration greater than 0.05 ug/mL (Ab*-hHb-Ab)

Front 39

Explain the Takayama reaction for blood?

Back 39

1. Hb = [NaOH + glucose + pyridine] = hemochromagen

2. the NaOH liberates the heme from globin

3. the glucose reduces the iron

4. pyridine combines with the iron to for hemochromagen (red feathery crystals)

Front 40

Definition of anti-immunoglobulin

Back 40

-acting against specific antibodies

-an antibody that bind antibodies

Front 41

define antibody and antigen

Back 41

-antibody: body produces in response to foreign objects like virus/bacteria; protein produced by B-cells (type of lymphocyte)l used by immune system

-antigen: substance that binds specifically to the respective antibody (the foreign body); provokes an adaptive immune response; foreign or toxic to body

Front 42

What is the Teichman test for blood?

Back 42

-confirmatory test for hemoglobin

-solution= KBr, KCl, KI in glacial acetic acid--> heated to react with Hb--> converts Hb--> hemin--> then the halides react with hemin to form characteristic brownish-yellow rhomboid crystals

Front 43

Hematrace can give false positives to what? why?

Back 43

-reacts with: any higher primate blood and ferret hemoglobin

*reacts with ferret blood because it shares common amino acid sequence with that of higher primates on the alpha chain of the hemoglobin molecule

Front 44

Composition of blood

Back 44

-water

-gases

-liquids

-proteins

-enzymes

-nitrogenous product

Front 45

Control area of Hematrace contains what?

Back 45

-immobilized anti-anti-hHb antibody (anti-immunoglobulin antibody)

=>forms pink band because any anti-hHb that dye marked was left unbound to hHb will be carried to the control area

Front 46

What is the Ouchterlony test?

Back 46

-species identification by radial diffusion of antigen and antibody through agar gel

-outer wells have stain and controls

-center well has ant-human antiserum

-diffusion outward from wells, precipitin band forms when stain contains protein recognized by IgG molecule in antiserum

Front 47

What do positive and negative Ouchterlony tests look like?

Back 47

Front 48

Describe the hemoglobin structure

Back 48

-conjugated protein: prosthetic group, protein portion, 2 alpha and 2 beta polypeptides, 4 heme groups

-part of the RBC

Front 49

Define peroxidase

Back 49

the actual enzyme that catalyzes the oxidation of a reduced substrate in presence of hydrogen peroxide (H2O2)

Front 50

What is the Takayama test?

Back 50

-hemochromagen test

-Ferrous Iron from Hb reacts with pyridine to produce red feathery crystals of pyridine ferroprotoproplyrin

-confirmatory test for hemoglobin by creating characteristic crystals

Front 51

What are the conclusions that can be drawn from ABAcard Hematrace test results?

Give examples of when you would be likely required to perform this test.

Back 51

-confirmatory test for blood

-not specific to just human blood

-can use to determine or rule out species of blood origin if TMB test is suspected to give positive result because of insults

EX. 1. if TMB+ but no DNA profile, could possibly be a lower animal species

EX. 2. use if TMB test is inconclusive

Front 52

Properties of blood? Shape as it leaves body? Do smaller or larger blood droplets travel farther?

Back 52

-viscoelastic, non-Newtonian fluid

-blood forms sphere when it leaves the body

-the surface tension keeps it together

-air resistance/gravity act on blood as it leaves body

-force behind bloodstain--> larger blood droplets travel farther than smaller (remember baseball v. wiffleball)

Front 53

Define monoclonal antibody

Back 53

-more specific than polyclonal (because single type of binding site)

-derived from a single cell line (fuse myeloma[cancer cells] cells with spleen cells from a mouse that's been immunized with the desired antigen)-->then the desired antibodies are extracted & purified

-myeloma + spleen cells = hybridoma

Front 54

define polyclonal antibody

Back 54

-not as specific as monoclonal (because multiple types of binding sites

-produced by inoculation of a mammal (mouse, rabbit, goat, etc)--> antigen is injected into mammal-->B lymphocytes produce IgG immunoglobulins specific for the antigen-->the polyclonal IgG is purified from the mammal's serum

Front 55

What is IgG?

Back 55

-immunoglobulin G

-Y shaped

-antibody isotype

Front 56

Fluid portion of blood

Back 56

-plasma abd serum

-plasma minus clotting factor = serum

-plasma consists of plasmoproteins and non-cellular material that aids in transport, functions heavily with the kidney in pH/ion balance

Front 57

What does the "30" in p30 stand for?

Back 57

the molecular weight in Daltons of the antigen

Front 58

Why are the sperm head routinely seen on microscopic smears missing their tails?

Back 58

-tails are 1st component of sperm to breakdown after ejaculation

-after 6 hours--> 25%sperm lose tails

-by 12 hours--> only a few with tails left

-by 24 hours--> mainly heads left

-tails are made of protein and are water soluble--> when they come in contact with other water molecules like in vaginal fluid--> start to degrade

Front 59

AP reaction IN THE BODY

Back 59

Front 60

What is p30?

Back 60

-glycoprotein from epithelial cells of prostate

-found in urine--> attributed to the drainage of prostatic ducts into the urethra

-females are devoid of p30

Front 61

Describe how sperm is delivered to the body exterior?

Back 61

-system of ducts:

1. Epididymis -->

2. ductus (vas) deferens -->

3. ejaculatory duct -->

4. urethra

Front 62

False positives for p30 test

Back 62

-male urine (reported p30 mean value of 260 ng/mL)

-results should be interpreted in conjunction with other info in the case

Front 63

Sperm physiology

Back 63

-formed within seminiferous tubules

-immature spermatozoa (not capable of mobility of fertilization) move to epididymis to complete maturation

-mature cells enter was deferens and stay there until ejaculation

Front 64

What does a normal sperm head look like?

What are possible causes of deformed sperm heads?

Back 64

-normal sperm= oval head with long tail

-abnormal= large or misshapen head, crooked or double tail

-causes: disease(celiac, Hodgkins, crowns), infections, high fever, drug/alcohol use, congenital testicular abnormalities

-toxin exposure= lowers sperm motility

-varicocele scrotum= enlargement of veins within scrotum= coiled tails

Front 65

What's cut and tied during a vasectomy?

Back 65

Vas deferens

Front 66

When do we use picric acid?

Back 66

-when making picroindigocarmine (green dye)

-during creatinine test

Front 67

What are the male accessory sex glands?

Back 67

*they empty their secretions into the ducts during ejaculation

1. Seminal vesicles

2. Prostate

3. Bulbourethral glands

Front 68

Where is sperm held before ejaculation?

Back 68

The epididymis (which contracts during ejaculation)

Front 69

P30 test A. positive B. negative C. inconclusive/invalid

Back 69

A. lines in test and control areas (indicates p30 level is greater than or equal to 4 ng/mL)

B. line in control area only (no p30 present above 4 ng/mL or high dose hook effect)

C. no visible line in control area (test didn't work)

Front 70

Describe sperm morphology

Back 70

-head= ~4.5 um, ~2.5 um wide

-tail= ~40 um long

-plasma membrane surrounds the sperm cell, and includes highly sulfated lipids

-mtDNA in midpiece of sperm

Front 71

If a stain is AP + and the slide is negative for sperm, do you have to perform a p30?

Back 71

YES! You HAVE to

Front 72

What can cause low sperm count?

Back 72

-high body heat

-certain medication

-diseases or testicular cancer

-excessive exercise

-drugs/alcohol

-excessive ejaculation

-age

-injuries

-surgery

-varicose veins in scrotum

-vasectomy

Front 73

What is seminal plasma secreted by? Functions?

Back 73

-secreted by: Bulbourethral glands, prostate gland, seminal vesicles (the majority)-function: vehicle for sperm, provides nutrients for sperm, activates sperm, coagulation/vaginal plug*TRANSPORT and NUTRITION

Front 74

What may affect the number of sperm in a typical male ejaculate?

Back 74

-disease

-genetics

-drugs/alcohol

-vasectomy

Front 75

What does the test area on a p30 test strip contain?

Back 75

-immobilized monoclonal antihuman p30 antibody

-captures Ab-Ag complex from the sample area and forms Ab*-Ag-Ab "sandwich"

-conjugated pink dye particles concentrate in a narrow zone on the membrane

-when {p30} is greater than 4 ng/mL= pink color test band

Front 76

What are the components of the AP reagents, and their functions?

Back 76

1. sodium-alpha-napthyl phosphate

2. o-dianisidine

*if acid phosphatase is present, it will cleave the phosphate group= producing a free napthol (-OH group)= napthol then binds with o-dianisidne to form purple azo dye

-a positive reaction is a purple color change within 15 seconds

Front 77

Christmas Tree Stain (components and procedure)

Back 77

-Nuclear Fast Red, 10 minutes, wash with dH2O

-Picroindigocarmine, 5-10 seconds, wash with reagent alcohol

-stains: sperm heads red, nuclei red/purple, epi cells and sperm tails green

-yeast cells also stain red/purple

Front 78

Possible reasons for AP positive reaction and no sperm being visualized?

Back 78

-may indicate semen is present without sperm: possible low sperm count (oligospermia), vasectomy (azospermia), still produce semen but not sperm

*p30 test MUST be performed next

Front 79

What are the confirmatory tests for semen?

Back 79

1. microscope with Xmas tree stain

2. p30 test--> conclusive for prostatic antigen

Front 80

Importance of acid phosphatase and its activity in the body?

Back 80

-functions in sperm mobility

-phosphatase= want free phosphate groups in semen to make ATP, which is used for energy when it's broken down

Front 81

What is p30? and how is its testing of value to the forensic biologist?

Back 81

-testing for p30 can identify that semen is present in the sample even if sperm cells are not visualized in the sample

-p30= prostate specific antigen

Front 82

What causes semen stains to fluoresce?

Back 82

-bacteria (pseudomonas fluorescens)

-flavins (in seminal plasma)

Front 83

Where does p30 originate?

Back 83

-originates in the prostate= only found in high concentrations in human semen

Front 84

p30 + AP results meaning?

Back 84

1. AP +, micro neg, p30 neg= insult may have cleaved the phosphate in alpha-napthyl= false AP +

2. AP +, micro neg, p30 + = azospermatic, human semen w/o sperm cells

Front 85

Example of potential false positives in presumptive testing of suspected semen stains?

Back 85

• urine and vaginal secretions= contains acid phosphatase, not as strong of a reaction as semen, will also fluoresce under ALS
• Other false + = fecal stains, cauliflower, contraceptive cream, sprouts, fungi, yeast & bacteria
  

Front 86

What does the control area on a p30 test strip contain? How does it work?

Back 86

-immobilized anti-immunoglobin antibody

-it captures unattached mobile p30 antibody (from sample area) which then creates a pink dye band

Front 87

What does the sample area of a p30 test contain?

Back 87

-mobile monoclonal antihuman p30 antibody with dye conjugate

-p30 will react with above to form a mobile antibody-antigen complex which will migrate to test area

Front 88

False negative for AP test?

Back 88

-spermacides

-feminine hygiene products (i.e. douches)

Front 89

Approximate pH of semen?

Back 89

~7.2 to 7.3

Front 90

Describe Acid Phosphatase and its functions

Back 90

-secreted from prostate

-function: human semen contains phosphorylcholine which is dephosphorylated to free choking and orthophosphate by AP

-phosphorylcholine is formed in the seminal vesicles and is dephosphorylated immediately after ejaculation

-free choking: lipotrepic (helps catalyze breakdown of fat during metabolism), stimulating action on the turnover of phospholipids, participant in transmethylation process

Front 91

Components of semen

Back 91

-cellular components

-spermatozoa

-seminal plasma (proteins, salts, organics)