tannins and calcium-phosphate--dibasic--anhydrous

A common problem in forensic DNA typing is PCR inhibition resulting in allele dropout and peak imbalance. In this paper, we have utilized the Plexor(®) real-time PCR quantification kit to evaluate PCR inhibition. This is performed by adding increasing concentrations of various inhibitors and evaluating changes in melt curves and PCR amplification efficiencies. Inhibitors examined included calcium, humic acid, collagen, phenol, tannic acid, hematin, melanin, urea, bile salts, EDTA, and guanidinium thiocyanate. Results were plotted and modeled using mathematical simulations. In general, we found that PCR inhibitors that bind DNA affect melt curves and CT takeoff points while those that affect the Taq polymerase tend to affect the slope of the amplification curve. Mixed mode effects were also visible. Quantitative PCR results were then compared with subsequent STR amplification using the PowerPlex(®) 16 HS System. The overall results demonstrate that real-time PCR can be an effective method to evaluate PCR inhibition and predict its effects on subsequent STR amplifications.

Topics: Bile Acids and Salts; Calcium Phosphates; Collagen; DNA Fingerprinting; Edetic Acid; Guanidines; Hemin; Humans; Hydrochloric Acid; Microsatellite Repeats; Models, Genetic; Phenols; Real-Time Polymerase Chain Reaction; Tannins; Thiocyanates; Urea

A mixture of alpha-tricalcium phosphate [alpha-Ca3(PO4)2; alpha-TCP] with a citric acid solution produces a hardened alpha-TCP-citric acid complex. The influence of tannic acid as an additive in the solution on the physical and chemical properties of the obtained complex was examined as a basic study for new calcium phosphate materials incorporating alpha-TCP. alpha-TCP was mixed with mixing liquids containing citric and tannic acids at various ratios [total acid = 45% (w/w)] at a powder/liquid = 2.2/1.0 (g/g). Compressive strength, setting time, and solubility & disintegration of the resulting complexes were measured by the methods specified by ADAS No. 61. After immersing the plates of the complexes in distilled water for 1 and 7 days, the surface structure of the plates was examined by using X-ray diffraction, scanning electron microscopy and IR spectroscopy. The substances solubilized and disintegrated in the water for 1 day were also examined by measuring quantitative Ca and P concentration. When the ratio of tannic acid to total acids (T/A) was higher than 30% (w/w), both setting time and solubility & disintegration increased remarkably. In the case of the complex at T/A = 30%, both setting time and solubility & disintegration showed the minimum value (6.25 min and 1.70%). For compressive strength, the maximum value (139 MPa) was obtained at T/A = 10%. Although the strength decreased markedly with increasing T/A beyond 10%, that of the complex at T/A = 30% was still a high level (103 MPa). The products on the surfaces before and after immersing the plates in distilled water were also discussed.

Topics: Calcium Phosphates; Citrates; Citric Acid; Dental Stress Analysis; Hydrolyzable Tannins; Solubility; Tannins; Time Factors