Biomedical subjects

Donald J Johnson

Publications and source records attributed to Donald J Johnson.

2 recordsLinked to original sources

PubMed2007

Variation in nuclear DNA concentrations during urination.

This study examined the cellular origin and concentration of nuclear DNA in human urine. Ten subjects provided two entire, first-morning voids: one as a single specimen and one as a consecutive series of samples. The serial samples were centrifuged, organically extracted, and quantified by slot-blot analysis. Total DNA concentrations ranged from 0.02 to 21.3 ng/mL for the males and 25.0 to 96.9 ng/mL for the females. The female samples were found to contain numerous vaginal epithelial cells. DNA was detected in all of the serial samples of nine subjects; however, the DNA concentrations varied considerably. With six subjects, the DNA concentration of the first serial sample was at least three times greater than that of the entire void. DNA was only detected in the first 21% of the void from one male subject. The results of this study have implications for the collection of urine samples.

Adult↗

PubMed2005

STR-typing of human DNA from human fecal matter using the QIAGEN QIAamp stool mini kit.

The purpose of this study was to compare the effectiveness of the QIAGEN QIAamp Stool Mini Kit against a standard phenolchloroform procedure for the extraction, quantitation, and STR-typing of human nuclear DNA from human feces. Stools from six subjects were sampled by swabbing and excision. Samples extracted with the QIAamp kit gave a wide range of DNA yields, whereas those extracted by the organic method yielded no DNA. DNA was not recovered from one subject's stools by either procedure. The QIAamp extracts were amplified with the Profiler Plus and COfiler kits, and PCR inhibition was observed with DNA extracts that were further concentrated. Substitution of water or TE-4 for the QIAamp elution buffer eliminated most, if not all, of the inhibition. A modified QIAamp procedure was used to extract thirty samples, which were subjected to one of five environmental conditions. DNA was recovered from all of these samples, and typing results were obtained on 93% of the samples.

Adult↗