PubMed · 8374184
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L M Irgens, N Oyen. 1993. Epidemiological definition.. https://doi.org/10.1111/j.1651-2227.1993.tb12867.x
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Human identification and forensic criminal casework may involve DNA profiling of decomposed material. Somatic microsatellite (STR) instability may lead to false exclusions and theoretically to false inclusions, both in criminal cases and in human identification. Hence, the somatic and postmortal stability of the actual sequences is crucial to the reliability of such analyses. Somatic STR stability in human tissues has been documented in small series only and the effect of postmortal tissue decomposition on microsatellite stability remains to be elucidated. On this basis, we have systematically searched for somatic STR mutations in 26 deceased humans without signs of decomposition at autopsy and 25 autopsy cases with obvious signs of postmortal decomposition. A blood sample and six tissue samples were collected from each case. Seven STRs were chosen for study, the tetranucleotides HUMVWA31/A, HUMTH01, HUMF13A1, and HUMFES/FPS, and the hyperpolymorphic markers HUMAPOAI1, D11S554 and HUMACTBP2. Denaturing gel electrophoresis was performed on an ABD Prism 377 gene sequencer with Genescan 672 software (Applied Biosystems, Inc.). The bone DNA profile of each case was chosen as the standard DNA profile. All cases gave profiles from additional tissues. By intraindividual comparison of DNA profiles in the cases without signs of degradation we find that the short repetitive sequences under study are stable, that is without evidence of somatic mutations. The cases with varying degree of decomposition display postmortal microsatellite stability, we detect no somatic mutations or other possible postmortal changes that could lead to between-organ non-matches. In conclusion, PCR-based STR analyses are suitable in human identification and forensic casework dealing with different tissues, even when the substrate is heavily decomposed.
The development of primary cancers and their subsequent metastases occur through a complex sequence of discrete steps. A hypothesis is proposed here whereby the time available for the growth of metastases is normally distributed, presumably as a consequence of the summation of multiple independently distributed time intervals from each of the steps and of the Central Limit Theorem. For exponentially growing metastases, the corresponding size distribution would be lognormal; Gompertzian growth would imply a modified (Gompertz-normal) distribution, where larger metastases would occur less frequently as a consequence of a decreased growth rate. These two size distributions were evaluated against 18 human autopsy cases where precise size measurements had been collected from over 3900 macroscopic hematogenous organ metastases. The lognormal distribution provided an approximate agreement. Its main deficiency was a tendency to over-represent metastases greater than 10 mm diameter. The Gompertz-normal distribution provided more stringent agreement, correcting for this over-representation. These observations supported the hypothesis of normally distributed growth times, and qualified the utility of the lognormal and Gompertz-normal distributions for the size distribution of metastases.
A simple, reliable and sensitive gas chromatographic-mass spectrometric method was devised to determine the level of mannitol in various human brain tissues obtained at autopsy. Mannitol was extracted with 10% trichloroacetic acid solution which effectively precipitated brain tissues. The supernatant was washed with tert.-butyl methyl ether to remove other organic compounds and to neutralize the aqueous solution. Mannitol was then derivatized with 1-butaneboronic acid and subjected to GC-MS. Erythritol was used as an internal standard. For quantitation, selected ion monitoring with m/z 127 and 253 for mannitol and m/z 127 for internal standard were used. Calibration curves were linear in concentration range from 0.2 to 20 microg/0.1 g and correlation coefficients exceeded 0.99. The lower detection limit of mannitol in distilled water was 1 ng/0.1 g. Mannitol was detected in control brain tissues, as a biological compound, at a level of 50 ng/0.1 g. The precision of this method was examined with use of two different concentrations, 2 and 20 microg/0.1 g, and the relative standard deviation ranged from 0.8 to 8.3%. We used this method to determine mannitol in brain tissues from an autopsied individual who had been clinically diagnosed as being brain dead. Cardiac arrest occurred 4 days later.