Melanie Grabmüller

Dysregulation of heart and brain specific micro-RNA in sudden infant death syndrome

Channelopathic heart arrhythmias and dysfunctional autonomic regulation of respiration and arousal based on defects in the brainstem are assumed to be involved in the pathogenesis of SIDS. There is evidence that, apart from mutational alterations in associated genes, disruption of physiological processes and deficient responses to external stressors may be influenced by the dysregulation of organ specific micro-RNA expression. It is unknown, however, whether these small, non-coding regulatory RNA molecules are involved in any SIDS pathomechanism. In a case-control study of two series of fresh-frozen heart tissue (n=14) and formalin fixed, paraffin embedded brainstem tissue (n=11) from SIDS and respective control cases, differential expression of heart and brain specific miR-1/miR-133 and miR-124a/let-7b, respectively, was determined using quantitative PCR analysis. Our results show a significant upregulation of heart specific miR-1 and brainspecific let-7b in SIDS compared to control cases. This pilot study is first to analyze differential miRNA expression in SIDS. Our findings suggest that organ specific miRNA dysregulation may be associated with SIDS pathogenesis and establishes the feasibility of miRNA analysis in different kinds of preserved and archived SIDS tissues.

Simultaneous analysis of nuclear and mitochondrial DNA, mRNA and miRNA from backspatter from inside parts of firearms generated by shots at ''triple contrast'' doped ballistic models

Abstract When a firearm projectile hits a biological target a spray of biological material (e.g., blood and tissue fragments) can be propelled from the entrance wound back towards the firearm. This phenomenon has become known as “backspatter” and if caused by contact shots or shots from short distances traces of backspatter may reach, consolidate on, and be recovered from, the inside surfaces of the firearm. Thus, a comprehensive investigation of firearm-related crimes must not only comprise of wound ballistic assessment but also backspatter analysis, and may even take into account potential correlations between these emergences. The aim of the present study was to evaluate and expand the applicability of the “triple contrast” method by probing its compatibility with forensic analysis of nuclear and mitochondrial DNA and the simultaneous investigation of co-extracted mRNA and miRNA from backspatter collected from internal components of different types of firearms after experimental shootings. We demonstrate that “triple contrast” stained biological samples collected from the inside surfaces of firearms are amenable to forensic co-analysis of DNA and RNA and permit sequence analysis of the entire mtDNA displacement-loop, even for “low template” DNA amounts that preclude standard short tandem repeat DNA analysis. Our findings underscore the “triple contrast” method’s usefulness as a research tool in experimental forensic ballistics.

Functional single-nucleotide variant of HSPD1 in sudden infant death syndrome

Background:An insufficient stress response due to a genetically impaired heat shock protein (Hsp) could play a role in the pathogenesis in a subgroup of sudden infant death syndrome (SIDS) cases. Herein, we are the first to investigate whether a functionally impairing and thus pathogenic variant of the gene for Hsp60, encoded by HSPD1 (rs72466451), is correlated with the occurrence of SIDS.Methods:In a case–control study of a series of 133 cases of SIDS and 192 gender-matched German Caucasian control cases, the occurrence and distribution of the HSPD1 single-nucleotide variant (SNV) was analyzed using SNV genotyping by minisequencing.Results:The results show significantly increased frequency of the pathogenic variant of the HSPD1 SNV in a subgroup (4.5%) of SIDS cases.Conclusion:The results suggest that the pathogenic variant of rs72466451 may play a role in a subgroup of SIDS cases with impaired Hsp60-mediated stress response.