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Biomedical subjects

P R De Forest

Publications and source records attributed to P R De Forest.

11 recordsLinked to original sources
PubMed1990

The use of isoelectric focusing to identify rhinoceros keratins.

Keratins represent the principal structural proteins of hair. They are also found in horn, nail, claw, hoof, and feather. Hair and nail samples from human and canine sources and hair samples from mule deer, white tail deer, cat, moose, elk, antelope, caribou, raccoon, and goat were studied. Parrot and goose feathers were also analyzed. Keratins are polymorphic, and species differences are known to exist. Proteinaceous extracts of deer and antelope antlers and bovine and rhinoceros horn were prepared by solubilizing 10 mg of horn sample in 200 microL of a solution containing 12M urea, 74mM Trizma base, and 78mM dithiothreitol (DTT). Extraction took place over a 48-h period. A 25-microL aliquot of extract was removed and incubated with 5 microL of 0.1 M DTT for 10 min at 25 degrees C. Keratins were then separated by isoelectric focusing (IEF) on 5.2% polyacrylamide gels for 3 h and visualized using silver staining. At least 20 bands could be observed for each species studied. However, band patterns differed in the position of each band, in the number of bands, and in band coloration resulting from the silver staining process. Horn from two species of rhinoceros was examined. For both specimens, most bands occurred in the pH range of 4 to 5. Although similar patterns for both species were observed, they differed sufficiently to differentiate one from the other. As might be expected, the closer two species are related phylogenetically, the greater the similarity in the IEF pattern produced from their solubilized keratin.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Trajectory reconstructions. I: Trace evidence in flight.

This paper reviews the use of trace evidence recovered from spent bullets in helping to establish trajectories. The use of information derived from such trace evidence combined with that from geometrical techniques of trajectory reconstruction and other data is discussed. Five cases are reviewed in which the analysis of trace evidential materials adhering to bullets was used to help reconstruct the event.

Adult↗
PubMed1988

The morphology and evidential significance of human hair roots.

A discussion of the morphology of human hair roots is presented. In addition to descriptions of variants of the root appearance for hairs removed from follicles in the three classical growth phases, several other commonly occurring root configurations are described and illustrated with photomicrographs. The possible evidential significance of each in certain case situations is discussed.

Forensic Medicine↗
PubMed1986

Blood droplet dynamics--I.

The interpretation of bloodstain patterns at crime scenes has received increased attention in recent years. Important to an understanding of this is knowledge of the fundamentals of blood droplet formation and impact dynamics. A review of the literature reveals that a considerable amount of work has been done with aqueous drop dynamics. Workers in the forensic science area seem to have been unaware of this. In addition, some of the most important and comprehensive early work with blood droplet dynamics seems to have been forgotten. It is not cited in more recent publications dealing with bloodstain pattern interpretation. This literature is reviewed and discussed as well. The present study presents results of experiments with blood droplet dynamics and high-speed photographs of blood droplet impacts on stationary target surfaces. Some longstanding misconceptions of importance to forensic scientists engaged in crime scene reconstruction are discussed.

Blood↗
PubMed1986

Blood droplet dynamics--II.

An earlier companion paper to the present one dealt with a literature review as well as blood droplet formation and impacts to stationary target surfaces. The present paper discusses the results of experiments with moving target surfaces. These are discussed in the context of their correlation with blood droplet impacts to inclined stationary targets and with respect to the interpretation of bloodstain patterns at crime scenes where the target surface is capable of its own movement. A special belt device was designed and constructed for the experiments reported here. This motorized apparatus was used to drive paper belt target surfaces at various controlled speeds.

Blood↗
PubMed1976

A precipitin-inhibition test on denatured bloodstains for the determination of human origin.

A new method has been developed for determination of the species of origin of denatured bloodstains. Antiserum with known titer is incubated with the denatured bloodstain. If the bloodstain has the same origin as the antiserum, a substantial amount of antibody will be absorbed by the stain, resulting in an attenuation of the antiserum titer. By reacting the supernatant with a known serum by using immunodiffusion it is possible to detect any appreciable attenuation of the antiserum titer. We have been able to determine the species of origin of various denatured bloodstains using this inhibition method.

Blood Stains↗