Saliva
What does a + presumptive test for saliva mean?
*gave chemical indications for the presence of a-amylase, which is a component of saliva* + result means clearing greater than or equal to 1:500 control, since saliva has greater conc than other body fluids, this is a good indication that saliva may be present
Which wavelengths are best to ALS for saliva?
415 and 455nm wavelengths using 555 interference filters (yellow and orange goggles)
What are the components of saliva?
99% water, digestive enzyme a-amylase, lingual lipase, electrolytes, proteins mucin, IgA, and lysozyme
Can we distinguish btwn salivary/pancreatic a-amylase?
WE can not. But, other labs could use electrophoresis
How does radial diffusion test work?
a-amylase breaks down the starch, iodine dyes starch filled areas blue, so places with no starch are clear
What is in the amylase plates?
agarose gel infused with starch-->made from diffusion buffer (NaCl, sodium phosphate, and water, adjusted to pH 6.9) agar, and starch
What is the purpose of saliva?
aid in digestion, lubricate mouth and pharynx, disolve food for tasting, moisten food so tongue can compact it into a bolus to be swallowed
What are the two forms of amylase?
alpha and beta. alpha found in animals-- human, rodent, elephant, pig, primate-- and is an endoenzyme which breaks down starch starting at the C-O bond and works at the 1,4 glycosidic linkages. beta found in plants, and is an exoenzyme which can not continue past the 1,6 linkage, resulting in incomplete breakdown
What is a-amylase?
an enzymes which begins digestion of polysaccharides in the mouth by hydrolyzing the starch, breaking down into smaller oligosaccharides of linked glucose molecules
How does Phadebas test work?
commercially produced tablets with insoluble starch covalently bound to blue dye, add tablet to water and sample, amylase would break down starch and release water soluble blue dye
What components of saliva are forensically relevent?
enzymatic activity of amylase (starch iodine test), bacteria and flavins (fluorescence weaker than semen), squamous epithelial cells for DNA, ABO typing in secretors, historical use of thiocyanate, nitrite, and alkaline phosphatase
How does amylase mapping work?
for large items, very thin layer of starch-infused agarose gel on large plate, item placed on gel (alt, wetted filter paper pressed to item, then gel), weight applied 10-15 mins, item removed and gel stained with iodine, same principle as radial diffusion
What does an inc presumptive test for saliva mean?
inc result would be a clearing less than the 1:500 control, suggests being from another body fluid or low amylase activity, so --> inc for saliva not amylase
What is positive control for radial diffusion?
known saliva standard, dilutions 1:100 and 1:500 (this shows gel capable of producing diff sized clearing with diff concentrations, can account for variation btwn individuals/time of day)
What does a - presumptive test for saliva mean?
no chem indications, either: amylase (saliva) not present, enzymatic activity not functioning, or not enough present to yield a result
Where does saliva come from?
produced in serous cells of parotid gland, and serous/mucous cells of submandibular and sublingual glands
What presumptive tests do we have for saliva?
radial diffusion, amylase mapping, phadebas
How do we QC for amylase tests?
reagents and tablet lots QC'd before casework, + and - controls run along with samples, cleaning, PPE
Is a-amylase found in other body fluids?
semen, sweat, tears, breast milk, vaginal fluid, urine, pancreatic tissue, fecal material, blood serum of pancreatic cancer patients
Do other animals have a-amylase?
yes, rats, elephants, pigs, and higher primates