FRNSC 413 Exam V

saliva

colorless body fluid secreted by 3 pairs of glands in the human mouth

3 glands

sublingual, submandibular (submaxillary), parotid

saliva contains?

- blood group substance (BGS) (secretors)
- 99.4% water, two thirds of solid (~0.6%) is organic matter - primarily mucin and amylase (amylase concentration allows for detection of saliva)

what's in saliva?

- enzymes: salivary amylase (diastase or ptyalin) hydrolyzes starch to maltose and dextrins; alkaline phosphatase-hydrolyzes monoesters; lysozyme (muramidase)
- proteins such as glycoproteins, mucin
- buccal squamous epithelial cells
- inorganic constituents such as nitrite and thiocyanate

excretion of saliva

in mammals: exocrine glands produce saliva
in insects: salivary glands are often used to produce biologically important proteins such as silk or glues

exocrine glands

glands that secretes externally through a duct; examples of external glands: sweat, saliva, digestive glands

endocrine glands

release their products directly into the circulatory system via the capillary network (hormones: ductless glands)

function of parotid

person awake: the parotid secrete up to 20-50% of the saliva output (largest gland in pairs; facilitate mastication and swallowing and begin the digestion of starches)

function of submandibular

asleep: the parotid contributes almost no saliva; most of the nocturnal output is provided by the submandibular glands; smaller than parotid but produce serous fluid and mucus; ~65-70% of saliva in the oral cavity

secretes a mixture of serous and mucin

function of sublingual

mucous; ~5% of saliva in oral cavity; the parotid gland secrets mostly serous fluid that makes for the watery characteristics of saliva, while the sublingual glands produce mucin, saliva's viscous component

xerostomia

dry mouth

causes of xerostomia

radiation therapy (can be permanent) and chemotherapy (temporary) can cause hyposalivation

function of saliva

- digestion
- protection: considered part of the mucosal immune system; plasma cells within the salivary glands produce immunoglobulin A (IgA) antibodies
- maintenance of teeth: buffering capacity of saliva protects tooth enamel and contributes to dental health

significance of saliva forensic cases

- critical investigation tool: saliva found at a crime scene is a possible source of DNA
- saliva is commonly identified on evidence samples such as: cigarette butts, bite marks, eating and drinking utensils

need to recognize

...

production of saliva

adult produces between ~750 and 1500 mL of saliva per day; men have higher overall salivary flow rates than women

detection of saliva

saliva from the parotid glands contain salivary amylases, enzymes, which aids in the digestion of food (carbohydrates); most labs use amylase as the identification method - presumptive

amylase

ptyalin; amylase is found in high concentrations in the saliva of humans, pigs, rodents, and primates; amylase-hydrolase that starts the digestion of carbohydrates by breaking the alpha1-4 linkages of the glucose monomers in starch

In humans

2 types of alpha-amylases: AMY1 and AMY2 (two genetic loci); chromosome 1: code for two different amylases, both types break down starch and glycogen

Salivary variety (AMY1)

- breast milk
- perspiration
- amniotic fluid
- cervical mucus
- tears

pancreatic variety (AMY2)

- pancreas
- vaginal secretions
- seminal plasma
- fecal material

AMY1 & AMY2

both gene products also exist in serum, and in tissue homogenates of male and female reproductive tissue; amylase is reported in nasal secretion; therefore, finding amylase, even at a high concentration, is at best a presumptive test for saliva

Cells within saliva

NSEC (nuclear squamous epithelial cells); found natively in many places: exfoliated buccal epithelial cells, buccal cells, cheek cells; vaginal swabs or crotches of panties as NSEC's are native constituent of vaginal secretions; inside front of men's underwear and/or pants as tip on the penis (urethral meatus) can transfer small quantities of NSEC to the front of the underwear where the NSEC can accumulate

Cells within saliva

ASEC (anuclear squamous epithelial cells) - AKA skin cells, keratinized epithelial cells, and keratinocytes; both NSEC and ASEC are normal constituents of saliva: both keratinized and non-keratinized cells in oral cavity in different regions

identifying amylase in saliva

alpha amylase: humans; total breakdown of starch to maltose or glucose and dextrin: cleavage occurs in the middle, endo action

beta amylase

- plants: exo action; animal tissue do not contain this; microorganism in digestive tract may contain this
- analytical biochem: Todaka and Kanekatsu: stress on plants changes amylase activity; this is synthesized by bacteria, fungi, and plants; fruits ripen - this breaks starch into sugar, which gives the sweet flavor of fruits

Conclusion: identifying saliva

identifying saliva is based on detection of high levels of amylase in the sample; amylase is not specific for saliva as amylase is found in other body fluids: serum, urine, sweat, semen, feces

identifying saliva

absence of amylase does not mean absence of saliva; UV light can aid in the detection and location of saliva stains; the intensity of the fluorescence can vary; concentration, age, other body fluid masking the stain, substrate, all can factor in the intensity of saliva under ALS; saliva doe not fluoresce as intensely as semen

persistence of amylase

inactivated by heat (boil); strong acids; strong bases; salivary amylase loses activity upon dying and rehydration; partial DNA profile of the suspect reported from a breast bite mark of the victim's breast after she has been in water for more than 5 hours; buccal NSEC survived also