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The epidermis is composed of multiple cell strata where viable keratinocytes, in the basal layer (stratum basale (SB)), go through a range of steps with the final stage of being dead corneocytes in the outer most layer (stratum corneum (SC)). The differentiation, which can be thought of as programmed cell death, include several key processes that are essential for an intact skin barrier. The route from SB to SC is accompanied by changes, such as osmotic pressure and pH, that are believed to trigger some of these processes. In this project, HaCaT cells were incubated with, commonly used, skin care substances (urea, glycerol, transcutol and salicylic acid) to assess their impact on cell viability, by MTT-assay, and gene expression, by qPCR. Further, the relationship between osmotic pressure, viability and gene expression was studied. The excipients showed a dose-dependent decrease of keratinocyte viability which also was explained by elevated osmotic pressure when concentration was increased. Exceptions were however observed for transcutol, which showed protective features against osmotic stress. Upregulation of the genes were mainly observed when cells were treated with high concentrations. Involucrin was affected by the substances to a greater extent when compared to other markers. The upregulation of involucrin was however seen to be driven by the osmotic pressure rather than biological effects of the molecules. The project conclude that the viability and gene expression of the keratinocytes are highly related to the osmotic pressure and probably influences the differentiation to a greater extent than the molecules themselves.

Vid låga mängder av DNA, vilket det ofta är vid forensiska prover, är en lyckad DNA-analys beroende av ett effektivt DNA-extraktionsprotokoll. Bland flera kommersiellt tillgängliga extraktionsmetoder för DNA har tidigare studier visat att Chelex 100 resin, som idag används på Nationellt Forensiskt Centrum i Linköping, är en snabb och enkel metod utan toxiska ämnen, långa väntetider eller större kostnader och som även ger ett högt DNA-utbyte. På teknisk mikrobiologi i Lund har olika chelex-baserade protokoll för spårsäkring och extraktion tagits fram för att optimera det aktuella protokollet på Nationellt Forensiskt Centrum. I detta arbete kombinerades spårsäkringsteknik och DNA-extraktionsprotokoll från tidigare studier med olika rör och tops, med syftet att i bästa fall generera ett protokoll som är optimalt för de vanligast förekommande brottsplatsproverna. I resultatet observerades högre DNA-utbyte med reducerade volymer lyseringsbuffert, vilket användning av rör-i-rörsystem tillät. När rör-i-rörsystem sedan kombinerades med extraktionsprotokoll innehållande SDS, observerades en ökning i DNA-utbytet. När dessa två faktorer vidare kombinerades med en tops vars skaft kan klippas rakt av ökade DNA-utbytet ytterligare. Ett byte från mikrofugrör, som används på Nationellt Forensiskt Centrum idag, till ett rör-i-rörsystem reducerar lyseringsvolymen från ca. 600 µl till 200 µl vilket är en avgörande faktor för effektivare extraktioner. When handling low amounts of DNA, which often is the case with forensic samples, a successful DNA analysis is dependent on an effective DNA extraction protocol. Among many commercially available extraction methods for DNA, previous research has proved Chelex 100 resin, which is used at National Forensic Center in Linkoping, to be a quick and simple method without toxic substances, long waiting time or large costs, which in addition provides a high DNA exchange. At Applied Microbiology, Lund´s University, different chelex-based protocols for sampling and DNA extraction have been developed to optimize the present protocol at the National Forensic Center. In this study, sampling techniques and DNA extraction from previous studies was further combined with different tubes and swabs with the aim to, in best case, generate a protocol that is optimal for the most common crime scene samples. The results showed improved DNA yields with less extraction volume, which the tube in tube system made possible. When tube in tube system was combined with extraction protocols containing SDS, a higher DNA yield was observed. When these two factors were further combined with a cotton swab, whose shaft can be cut straight of, the DNA yield improved even more. A change from microfuge tubes, which is used at the National Forensic Center, to tube in tube system, the lysis volume could be reduced from approximately 600 µl to 200 µl which is a deciding factor for higher DNA yield.