Detection and correction of a migration anomaly on a 310 genetic analyzer

During STR analysis on the 310 Genetic Analyzer, retarded migration of GS500ROX size standards and alleles in some samples was observed. The contribution of reagents, capillary and performance optimized polymer POP 4 to the observed anomaly was experimentally eliminated. Variation in electrophoresis temperature between 55 degrees C and 65 degrees C did not alter the rate of migration of GX500ROX size standard and sample alleles. An eroded connector for the cathode mounted on the heat plate assembly caused the abnormal migration. Hence, it is important to verify the mobility of all fragments in the size standard for each sample to avoid any erroneous allele calls by the automated data analysis software.     

Loss of heterozygosity detected in a short tandem repeat (STR) locus commonly used for human DNA identification

Short tandem repeat (STR) markers are commonly used in basic genetic research and in human identification testing. Clinically, STRs can be used to study genetic alterations in tumors. A genetic deletion common to many types of cancer is referred to as the loss of heterozygosity (LOH). Numerous examples of LOH in cancer have been described and some have been mapped to areas located in close proximity to markers employed in human identity testing. Despite this fact, LOH has rarely been observed for STR loci commonly employed in forensic testing. Recently, for medico-legal purposes, we were asked to determine whether a tissue biopsy originated from a particular individual. For a reference source we assessed two specimens, one from normal tissue and one from cancerous tissue. When both reference specimens were used to generate DNA profiles, we observed LOH at one STR locus, D13S317. As demonstrated in other cancers only the cancerous biopsy demonstrated LOH. The forensic community should be cognizant of these unusual circumstances because, as identification of human DNA continues to be used more extensively, certain instances will arise in which reference material will not be readily available. In these situations, archived specimens may be employed as a reference source. Clinical specimens such as tissue biopsies should be used with caution if they have not been confirmed to contain normal tissue.     

Suicide by electrocution with low-voltage current

Three cases of suicide by electrocution with low-voltage current were observed in five years (1994-1998) by medical clinical forensic examiners of an Emergency Forensic Unit of the Paris suburb among 2,000 external death examinations. The cases involved one woman, aged 72 and two men, aged 38 and 41. In the last two cases, electric burns were retrieved under bared electric wires, placed on the arms or fingers in order to realize a hand-to-hand electric circuit involving the heart muscle. In the other case, the electric circuit between mouth and foot also involved the heart muscle. Household low-voltage current delivered (220 V in France) had a sufficient strength to induce local muscular paralysis and heart fibrillation. In the three cases, blood samples taken have retrieved very high levels of muscular enzymes (CPK, LDH) correlated to the mechanism of electric death. The rareness of suicide by electrocution and its forensic characteristics are detailed in order to help the clinical forensic examiners, prosecutors, and police officers concerned by such death examinations.     

Detection of semen in stains on material evidences by quantitative immunofluorescence test

Russian and foreign methods used in forensic medicine for detection of the semen in stains on material evidences are compared. The potentialities of quantitative immunofluorescence test for detection of the semen in stains on material evidences, developed at Bureau for Forensic Medical Expert Evaluations of the Leningrad region, are described. Unlike other methods used in Russia, this method detects the semen in stains in the absence of spermatozoa and in stains with very low amount of the semen. Our modification allows objective recording of the results with computer processing. The method is cheaper than its foreign analogs and its sensitivity is similar to them.     

Isolation of nitrobenzene from biological material

Toluene is recommended as an agent for extraction of nitrobenzene from biological material. Optimal conditions for nitrobenzene isolation from cadaveric human liver are defined and the results of isolation are quantitatively evaluated.     

Asphyxial death during prone restraint revisited: a report of 21 cases

Determining the cause of death when a restrained person suddenly dies is a problem for death investigators. Twenty-one cases of death during prone restraint are reported as examples of the common elements and range of variation in these apparently asphyxial events. A reasonable diagnosis of restraint asphyxia can usually be made after ruling out other causes and collecting supportive participant and witness statements in a timely fashion. Common elements in this syndrome include prone restraint with pressure on the upper torso; handcuffing, leg restraint, or hogtying; acute psychosis and agitation, often stimulant drug induced; physical exertion and struggle; and obesity. Establishing a temporal association between the restraint and the sudden loss of consciousness/death is critical to making a correct determination of cause of death.