Degradation of biomolecules in artificially and naturally aged teeth: implications for age estimation based on aspartic acid racemization and DNA analysis

Postmortem teeth are the most stable structures, and can be used to gain different information (age estimation, genetic data). Over long postmortem intervals (PMI), degradation processes may alter the molecular integrity and thus affect the reliability of applied molecular methods. Whereas some knowledge on the degradation of biomolecules in bone during the PMI exists, data for teeth are lacking. In particular, the impact of degradation processes in dentine on age estimation based on aspartic acid racemization (AAR) cannot be estimated yet. Hence, the molecular stability of both collagen and DNA was analyzed systematically, and their impact on the reliability of age estimation based on AAR and genetic analyses was checked. Two hundred and ten human and 59 porcine teeth were heated (90 degrees C in water) to simulate collagen and DNA diagenesis; 14 naturally aged teeth (PMI: 3 days to 1700 years) were analyzed comparatively. Peptide patterns of cyanogen bromide (CNBr)-cleaved collagen were employed as a new approach to check the collagen integrity. In the same samples, collagen yields, amino acid compositions, AAR in different protein fractions, and DNA integrity were analyzed. In heated human and porcine teeth the collagen content declined during the heating experiment. The amino acid composition in human samples was collagen-like until 12 days of heating. In naturally aged teeth, the collagen yielded from 9.5 to 15%, and no discrepancy of amino acid composition to that of modern collagen was observed. Electrophoresis of CNBr-peptides showed an altered pattern in experimentally degraded samples from day 10 on; naturally aged collagen displayed the typical collagen pattern. AAR increased in all protein fractions with increasing duration of the heating experiment; naturally aged samples displayed a slow accumulation of AAR. DNA degraded progressively, and after 32 h of heat exposure no more DNA was detectable, whereas the amplification of nuclear and mitochondrial DNA was successful up to 48 h. STR typing was reliable up to 16 h, and sex determination up to 40 h of heat exposure. In naturally aged samples of DNA quality, yield and typing success did not correlate with PMI. The data highlight a remarkable stability of collagen dental proteins. Within relevant forensic periods a postmortem rise of AAR under normal conditions is negligible, and analyses of dental DNA has a high chance to be successful. However, after large PMI and/or extreme postmortem conditions age estimation based on AAR and genetic analyses lose their reliability.     

Significance of hydrocyanic acid formation during fires]

Cyanide concentrations of blood samples from fire victims autopsied in the Institute of Legal Medicine, Munich, have been determined. In 25% of 48 analyzed cases cyanide concentrations from 0.52 microgram to 6.24 microgram Cyanide/ml blood have been detected. These results are compared to former studies and the higher mean level in our collective is emphasized. The importance of hydrocyanid acid in the toxicity of fire gases is evidently greater, than assumed. Hydrocyanic acid may be produced from nitrogen continaing polymers during combustion. The quote of these polymers in clothing, furniture, and also in equipment of cars is increasing. Therefore, it is necessary to take more notice of the formation of hydrocyanic acid during combustion, even though carbon monoxide is in general the main toxic agent in fire gases.     

Projecting the impact of the 1976 Medical Device Amendments on innovation in clinical chemistry tests

This paper is concerned with the impact of the Medical Device Amendments of 1976 and its implications in terms of innovation. With this objective the paper first describes the Medical Device Amendments of 1976. The paper then reports empirical evidence on the sources of a subset of innovations regulated by the Amendment's clinical chemistry diagnostic products. Finally, based on the pattern of innovations found, some thoughts are expressed about the likely effects of the Amendments.     

La régulation des affaires sociales: une analyse politique††

Sommaire. Le gouvernement peut être défini comme la régulation des affaires publiques¹ et à des fins d'analyse cette régulation, comme d'ailleurs les régulations privées, peut être distinpée en communication et en commandement. Pour que la régulation s'accomplisse, la communication doit être commandée, et le commandement communiqué. Nous nous situerons ici dans la première perspective:celle où la régulation est vue comme commandement de la communication. C'est la perspective de l'analyse politique, par opposition à une analyse davantage socio-économique qui se donnerait pour objet les phénomènes de communication eux-mêmes. Abstract. Government can be defined in terms of the regulation of public affairs. For purposes of analysis, public regulation, like private regulation, can be identified as communication and command. For regulation to be achieved, communication must be ordered and the order communicated. Here we will explore the first notion, the consideration of regulation as ordering communication. This is the viewpoint of political analysis, as opposed to a more socio-economical analysis which is concerned with the phenomena of communication itself.     

Family Factors in the Ego Development of Adolescent Girls

Thirty-nine adolescent girls, 16–19 years, were observed together with their 2 parents at a family discourse about moral and family issues on which they disagreed, to study interaction and conflict handling in families with daughters at different levels of ego development. Family interactions were coded by the Constraining and Enabling Coding System, ego development by the Washington University Sentence Completion Test and handling of internal conflict by Bond Defense Style Questionaire. Daughters' ego development was predicted by parental cognitive and affective enabling, but not by constraining communications. Fathers' cognitive and affective enabling transactions and mothers' affective enabling transactions contributed to the explained variance in the adolescents' ego development when daughters' age, parents' SES and ego development were controlled for in hierarchical regression analyses. Parents' ego levels were related to their enabling transactions, which also predicted daughters' ego levels, suggesting that especially enabling parenting behavior may play a mediating role. Mothers' challenging behavior toward daughters and parental autonomy from responding in kind to daughters' communications were also related to high ego levels in daughters.     

Reviews

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