Chapter 17: Identification of Urine, Sweat, Fecal Matter, and Vomitus

Nephron

The basic structural and functional unit of the kidney.

Glomerulus

It is formed by a network of capillaries and is surrounded by a Bowman’s capsule.

Nephron

The basic structural and functional unit of the kidney.

Glomerulus

It is formed by a network of capillaries and is surrounded by a Bowman’s capsule.

Filtration

the first step in urine formation.

Glomerular filtrate

The preliminary form of urine, consists of water, salts glucose, and waste products such as urea.

reabsorption

The filtrate is then passed through the renal tubule where _ occurs.

reabsorption process

During the _, water, glucose, nutrients, and ions such as sodium are reabsorbed back into the blood.

Secretion

It is the last process of urine formation. It occurs at the distal and the collecting tubules of the nephron where ions ammonia, and certain metabolites are secreted from the blood into the lumen of the renal tubule to be eliminated in the urine.

Urine

An aqueous solution consisting largely of water and waste products.

Urea

The most abundant waste product in urine, resulting from the elimination of ammonia that is produced from the metabolic process of amino acids.

para-dimethylaminocinnamaldehyde (DMAC) assay

The _ is simple and rapid and is the most commonly used presumptive assay for the forensic identification of urine stains.

colorimetric method

In the , a portion of a stain (~1 cm2) is cut and is extracted with 1 mL of distilled water. The extraction is transferred onto a piece of filter paper and is allowed to dry.

fluorometric method

The _ is useful for locating urine stains on large pieces of evidence such as clothing and bedding.

Jaffe color test

The creatinine present in urine can be detected using the _.

In this test, picric acid is used to convert creatinine, under alkaline conditions, to form creatinine picrate, which is a bright red product.

Tamm–Horsfall protein (THP)

Also known as uromodulin, is the most abundant protein in urine, and accounts for 40% of the urine proteins.

Androsterone

A steroid hormone with a weak potency of testosterone.

DHEA

A metabolic intermediate in the biosynthesis of the gonadal steroids. It also has a potential function as a steroid hormone.

Etiocholanolone

A metabolite of testosterone.

Eccrine sweat glands

Are distributed almost all over the body and are controlled by the sympathetic nervous system. It plays a role in regulating body temperature.

Apocrine sweat glands

Are associated with hair follicles, are usually restricted to the underarm and genital areas and are controlled by emotional stress.

Raman microspectroscopy

is potentially useful for the identification of sweat for forensic purposes, which is based largely on the profiles of lactate, lactic acid, urea, and single amino acids in urine.

Dermcidin

Identified as a potential biomarker of human sweat. It belongs to a class of human antimicrobial peptides of the innate immune defense system and plays an important role in protecting epithelial barriers from infections.

ELISA assays

The detection of dermcidin in sweat stains can be performed using _ utilizing antibodies specific to human dermcidin.

Feces

Are a type of waste matter that is the direct result of food that has been processed by the digestive system.

Urobilinoids

These are generated from the degradation of heme and are excreted into feces.

Schlesinger test

In the , a sample is mixed with saturated zinc acetate in ethanol solution to form aurobilinoid–zinc chelation complex that emits a characteristic green fluorescence under ultraviolet light.

Edelman test

The is a variation of the Schlesinger test. A sample is treated with a mercuric salt solution to yield a pink-colored compound. Further treatment with a zinc salt produces fluorescence.

Vomiting

The forceful expulsion of the contents of the stomach through the mouth. It is usually preceded by salivation, sweating, and the sensation of nausea.

Vomitus

is highly acidic and tends to be malodorous.

Pepsins

__ are endopeptidases that cleave primarily on peptide bonds in the middle of the protein.

Aromatic amino acids

such as tryptophan, phenylalanine, and tyrosine, are the preferred targeted amino acids for the cleavage reaction by pepsins.

fibrin blue

In the pepsin-proteolytic assay, _ is used as a substrate for pepsin.