New insights into the intracellular distribution pattern of cationic amphiphilic drugs

Cationic amphiphilic drugs (CADs) comprise a wide variety of different substance classes such as antidepressants, antipsychotics, and antiarrhythmics. It is well recognized that CADs accumulate in certain intracellular compartments leading to specific morphological changes of cells. So far, no adequate technique exists allowing for ultrastructural analysis of CAD in intact cells. Azidobupramine, a recently described multifunctional antidepressant analogue, allows for the first time to perform high-resolution studies of CADs on distribution pattern and morphological changes in intact cells. We showed here that the intracellular distribution pattern of azidobupramine strongly depends on drug concentration and exposure time. The mitochondrial compartment (mDsRed) and the late endolysosomal compartment (CD63-GFP) were the preferred localization sites at low to intermediate concentrations (i.e. 1 mu M, 5 mu M). In contrast, the autophagosomal compartment (LC3-GFP) can only be reached at high concentrations (10 mu M) and long exposure times (72 hrs). At the morphological level, LC3-clustering became only prominent at high concentrations (10 mu M), while changes in CD63 pattern already occurred at intermediate concentrations (5 mu M). To our knowledge, this is the first study that establishes a link between intracellular CAD distribution pattern and morphological changes. Therewith, our results allow for gaining deeper understanding of intracellular effects of CADs

Abundance and Distribution of Enteric Bacteria and Viruses in Coastal and Estuarine Sediments—a Review

The long term survival of fecal indicator organisms (FIOs) and human pathogenic microorganisms in sediments is important from a water quality, human health and ecological perspective. Typically, both bacteria and viruses strongly associate with particulate matter present in freshwater, estuarine and marine environments. This association tends to be stronger in finer textured sediments and is strongly influenced by the type and quantity of clay minerals and organic matter present. Binding to particle surfaces promotes the persistence of bacteria in the environment by offering physical and chemical protection from biotic and abiotic stresses. How bacterial and viral viability and pathogenicity is influenced by surface attachment requires further study. Typically, long-term association with surfaces including sediments induces bacteria to enter a viable-but-non-culturable (VBNC) state. Inherent methodological challenges of quantifying VBNC bacteria may lead to the frequent under-reporting of their abundance in sediments. The implications of this in a quantitative risk assessment context remain unclear. Similarly, sediments can harbor significant amounts of enteric viruses, however, the factors regulating their persistence remains poorly understood. Quantification of viruses in sediment remains problematic due to our poor ability to recover intact viral particles from sediment surfaces (typically <10%), our inability to distinguish between infective and damaged (non-infective) viral particles, aggregation of viral particles, and inhibition during qPCR. This suggests that the true viral titre in sediments may be being vastly underestimated. In turn, this is limiting our ability to understand the fate and transport of viruses in sediments. Model systems (e.g., human cell culture) are also lacking for some key viruses, preventing our ability to evaluate the infectivity of viruses recovered from sediments (e.g., norovirus). The release of particle-bound bacteria and viruses into the water column during sediment resuspension also represents a risk to water quality. In conclusion, our poor process level understanding of viral/bacterial-sediment interactions combined with methodological challenges is limiting the accurate source apportionment and quantitative microbial risk assessment for pathogenic organisms associated with sediments in aquatic environments

Chirale Allenylcarbamate, Darstellung und Verwendung in der enantioselektiven Synthese

Im ersten Teil der Dissertation wurde die (-)-Spartein-vermittelte Deprotonierung von verschiedenen 2-Akinylcarbamaten untersucht. Hierbei zeigt es sich, daß hohe Enantiomerenanreicherung nur durch eine selektive Kristallisation eines Diastereomeres der beiden konfigurativ labilen Lithium-Carbanion-Komplexe zu chiralen Allenyl- und Alkinylcarbamten nach der elektrophilen Substitution führt. Der stereochemische Verlauf der Reaktion wurde zweifelsfrei aufgeklärt. Durch eine Umwandlung der 2 ten Art kristallisiert selektiv der (S)-konfigurierte Lithium-Carbanion-Komplex ) aus. Dieser wird aus dem Gleichgewicht entfernt und durch Epimerisierung nachgebildet, so daß sich das hochenantiomerenangereicherte Lithiumorganyl im Kristallisat anreichert. Die anschließende stereospezifische Substitution führt zu hochenantiomerenangereicherten Aklinylcarbamten bzw. im Falle einer Transmetallierung C1Ti(Oi-Pr) 3 zu chiralen Allenylcarbamaten

Identification of pyrazolopyridazinones as PDEδ inhibitors

The prenyl-binding protein PDEδ is crucial for the plasma membrane localization of prenylated Ras. Recently, we have reported that the small-molecule Deltarasin binds to the prenyl-binding pocket of PDEδ, and impairs Ras enrichment at the plasma membrane, thereby affecting the proliferation of KRas-dependent human pancreatic ductal adenocarcinoma cell lines. Here, using structure-based compound design, we have now identified pyrazolopyridazinones as a novel, unrelated chemotype that binds to the prenyl-binding pocket of PDEδ with high affinity, thereby displacing prenylated Ras proteins in cells. Our results show that the new PDEδ inhibitor, named Deltazinone 1, is highly selective, exhibits less unspecific cytotoxicity than the previously reported Deltarasin and demonstrates a high correlation with the phenotypic effect of PDEδ knockdown in a set of human pancreatic cancer cell lines

A general approach to homochiral alpha-amino substituted bromo-heteroaromatics suitable for two-dimensional rapid analogue synthesis

An efficient and general synthesis of homochiral alpha-amino substituted bromo-heteroaromatics B using a diastereoselective 1,2-addition has been developed. The obtained heteroaromatic intermediates allow for a rapid two-dimensional exploration of a new series of histone deacetylase inhibitors, through Suzuki-Miyaura cross-coupling reactions for the introduction of a second aromatic element, followed by global deprotection and derivatization of the amino group. (C) 2009 Published by Elsevier Ltd