The effect of chronic alcohol consumption on mitochondrial DNA mutagenesis in human blood.

The 4977bp deletion of mitochondrial DNA (mtDNA) is known to accumulate with increasing age in post mitotic tissues. Recently, studies came out detecting this specific alteration also in fast replicating cells, e.g. in blood or skin tissue, often in correlation to specific diseases or -- specifically in skin -- external stressors such as UV radiation. In this study, we investigated mitochondrial mutagenesis in 69 patients with a chronic alcoholic disease and 46 age matched controls with a moderate drinking behavior. Two different fragments, specific for total and for deleted mtDNA (dmtDNA) were amplified in a duplex-PCR. A subsequent fragment analysis was performed and for relative quantification, the quotient of the peak areas of amplification products specific for deleted and total mtDNA was determined. Additionally, a real time PCR was performed to quantify mtDNA copy number. The relative amount of 4977bp deleted mtDNA in alcoholics was significantly increased compared to controls. On the other hand, no difference regarding the mtDNA/nuclear DNA ratio in both investigated groups was detected. Additionally, no age dependence could be found nor in alcoholics, neither in the control group. These findings indicate that mtDNA mutagenesis in blood can be influenced by stressors such as alcohol. Ethanol seems to be a significant factor to alter mitochondrial DNA in blood and might be an additional contributor for the cellular aging process.

Detection of constitutive and inducible HSP70 proteins in formalin fixed human brain tissue.

The investigation of formalin fixed and paraffin embedded tissue is a routine method in forensic histology. Since these samples are usually stored for decades they provide a unique tissue bank for different scientific issues. In the past, numerous studies were conducted using different kinds of paraffin embedded tissues. However, it is well known that formalin affects macromolecules and thus might hamper reliable and reproducible molecular experiments. The aim of this study was to find out if the treatment with formalin has a negative effect on different protein detection methods and additionally to define the dimension of those possible deleterious effects. We incubated brain tissue samples in formalin for up to three months. After incubation, the samples were analyzed using immunohistochemistry (IHC) and Western blotting to specifically detect and quantify members of the HSP70 superfamily (heat shock proteins). Our study shows that the Western blot analysis of formalin fixed tissues does not allow a reliable detection of proteins at all, while a reproducible detection by IHC was still possible after one month of incubation.

Phantoms in the mortuary--DNA transfer during autopsies.

DNA evidence frequently plays an important role in criminal investigations and in some cases may be the only means of convicting a suspect. The constant improvement of DNA analysis techniques affords the individualization of minute amounts of DNA, aggravating the risk of contamination artifacts. In our study, we investigated the prevalence of DNA contamination in the autopsy facilities of the Institutes of Legal Medicine in Essen and Kiel (Germany). Using DNA-free swabs, we took samples from instruments used during autopsy and autopsy tables. Surfaces and instruments were routinely cleaned before sampling. Swabs were subjected to different PCRs to quantify the total amount of DNA and to amplify individual specific STR-markers. In most samples, alleles that could be linked to bodies that had been autopsied before were found. Furthermore, we could show that a DNA transfer from the autopsy table to a body was detectable in four out of six cases investigated. The interpretation of DNA typing results may thus be severely complicated. To avoid DNA contamination, we tried out different cleaning methods, of which only a bleach containing cleaner showed sufficient results.

Mast cell reactivity at the margin of human skin wounds: an early cell marker of wound survival?

Detecting the vitality of mechanical skin wounds (antemortem versus postmortem injury) in human cadavers remains a specifically forensic problem. To determine whether skin mast cells (MCs) are activated during the very early phase of human wound healing we performed a histomorphometric evaluation of the extent of MC enzyme loss as an indication of MC degranulation at the wound margins of skin wounds in 64 human cadavers. We compared the number of tryptase-reactive MCs, which are said not to loose all of their enzyme activity during degranulation process, with the number of naphthol AS-D chloroacetate esterase (NAS-DClAE)-positive MCs, which loose their complete enzyme activity in the form of enzyme-positive granula after activation. The enzyme activity was evaluated on sequential histological sections after autopsy as an indirect quantification of the number of degranulated MCs. Most of the victims had died within 10-60 min after injury (n=50), 12 survived between 60 min and 24h, and only 2 victims survived more than 24h (12 days each). The number of enzyme-positive MCs were counted in six successive visual fields (0.785 mm(2)) on the one hand located parallel to and--on the other hand--at increasing distances outward from the wound margins. In victims surviving the injury less than 60 min the average number of NAS-DClAE-reactive MCs next to the wound margin was significantly lower than the number of tryptase-reactive MCs. The extent of the reduction in NAS-DClAE-reactive MC counts correlated inversely with the distance from the wound edges. Our findings show that MCs undergo very early loss of NAS-DClAE activity at wound margins, and thus appear to be an early cell marker of wound survival. However, definitive evidence that the enzyme loss (degranulation) represents a vital process can only be obtained by comparing MC enzyme loss induced by injury during intact circulation with the MC reaction to injury inflicted very shortly after cardiac arrest, a question that can only be answered by animal experiments.