α‐Amylase Kinetic Test in Bodily Single and Mixed Stains

Abstract

Recently, in Italy, a murder and a putative sexual violence was accomplished on a child. A bodily fluids mixture on the child's underwear between the victim (female) and the suspect (male) was ascertained by short tandem repeat (STR) DNA typing and, due to the absence of seminal fluid, saliva from the suspect and urine from the child was hypothesized. In order to investigate the possibility of specifically and rapidly detecting saliva stains both alone and mixed with other bodily fluids, we used a quantitative spectrophotometric technique, named Amylase test, for the detection of alpha-amylases. We determined alpha-amylase activity and reaction kinetic curves in several samples collected from the child's underwear. In order to confirm our intuition, we first tested saliva, perspiration, and urine, singularly and in mixtures; second, several forensic stains including saliva, perspiration, urine stains, saliva/perspiration, and saliva/urine mixture stains were tested. Evaluating alpha-amylase activity values and time-course curves' behavior of alpha-amylase reactions we were able to recognize successfully, in all cases, the presence of saliva and to distinguish it specifically from other bodily fluids containing alpha-amylase. A further confirmation of our result was provided by STR DNA typing on several areas of the underwear: a clear correlation between alpha-amylases activity and male DNA was detected on all the samples evaluated.

False‐Positive Results with Amylase Testing of Citrus Fruits

“…Human salivary α‐amylase is the major protein component in human saliva and is found at very high levels . As α‐amylases are secreted into the digestive system, small amounts diffuse into the bloodstream and are eliminated through urine and perspiration; these enzymes can also be recovered in other biological fluids such as serum, male, and female reproductive tissues and feces . There are different presumptive saliva identification systems that can be used to detect α‐amylase activity , but they do not distinguish the two human α‐amylase isoenzymes or plants, bacteria, and fungi α‐amylase .…”

Advantages of application of colorimetric express methods to establish the presence of saliva in stains, traces and sites on the material evidences

“…Наши зарубежные коллеги применяют для дан ной цели другие методики: тест на амилазу по Фа дебазу [8], визуальный тест на уринарную амилазу [11,13]; специальные тест полоски (стрипы), меня ющие свою окраску при наличии амилазы в иссле дуемых вытяжках [12], метод иммуноферментного анализа (ИФА) [9] и кинетический метод [7], осно ванные на объективной количественной регистра ции амилазы в исследуемых вытяжках. Особо важ но отметить факт, что зарубежом выделяют две различные формы a амилазы, продуцируемые че ловеческим организмом: a амилаза 1, которая со держится в слюне грудном молоке и потожиро вых выделениях, а также a амилаза 2, которую на ходят в секрете поджелудочной железы, сперме и влагалищных выделениях.…”

Salivary Diagnostics, Current Reality and Future Prospects

“…For the salivary diagnosis become routine in clinical practice, it is necessary to know specific salivary biomarkers of disease states or health, besides technology necessary for their detection [74]. The genomics, epigenomics, transcriptomics, proteomics and metabolomics ( Figure 3) approaches are currently being used to characterize these diagnostic biomarkers in saliva [75].…”