The estimation of the time of death by non-protein nitrogen (NPN) in cadaveric materials. Report 3: multiple regression analysis of NPN values in human cadaveric materials

The non-protein nitrogen (NPN) values in brain, lung, liver, and kidney in 79 autopsy cases were determined according to the Micro-Kjeldahl Nessler method. Multiple regression analysis of the data was performed with every possible combination of the time of death and the NPN values in the tissues. The brain NPN showed the best correlation with the postmortem time (r = 0.673), whereas the other correlations were less satisfactory (lung r = 0.422, liver r = 0.397, and kidney r = 0.379, respectively). However, multiple combinations of each tissue NPN value proved to give better correlation coefficients and smaller errors of the estimated time of death. The practical significance of the tissue NPN as a postmortem biochemical indicator of the time of death and the multiple regression analysis of such indicators were extensively discussed in this report.

[Investigations to determine the time of death, late post mortem, by means of electrophoresis of inner organs (author's transl)]

In CAF-electrophoresis, extracts of cardiac muscle and of kidney tissue, after storage at 4 degrees C, show a roughly linear increase of the equivalent to the Albumin fraction. This increase depends on the time elapsed and is explained by the relatively high stability of this fraction compared to organ proteins, which appear in the globulin region. Thus, a sort of internal standard exists and can be used as a parameter for the determination of the post mortem period. Hepatic tissue is less suitable for this kind of investigations as the relation of the post mortem period and the values of the relative concentration of the fraction do not show the linearity found in cardiac muscle and kidney tissue. Splenic tissue shows no distinct trend and the findings are of little value. The present investigations were arranged in such a way that taking the order of magnitude for the equivalent of the Albumin fraction as a guideline led to a determination of the maximum post mortem period, i.e., the maximum period of time the body lay after the hour of death. The tables of this paper show the figures for the individual organs.

[Identification and significance of delta-aminovaleric acid in putrefaction materials (author's transl)]

During former putrefaction experiments regularly a proteogenic substance has been found which by means of modern analytical methods now was identified as delta-aminovaleric acid (DAVA). DAVA seems to appear in guinea pig as well as human organs and some body fluids under experimental conditions never before the 3rd (20 degrees C) to 5th day (10 degrees C). It is characterized by statistically significant increases until the end of the 2nd (20 degrees C) to 5th week (10 degrees C) and relatively stable values thereafter. Considering storage temperature measurement of DAVA concentration can be of relevance for the estimation of the time of death in cases of putrescent corpses.