Flavonol-Derivate in Formen der Gattung Vitis

In einem ersten Ansatz, dem weitere Absicherungen und Identifizierungen durch Isolierung größerer Substanzmengen folgen sollen, wurden die Blätter von vier Rebenformen auf ihren Flavonoidgehalt hin untersucht. Vergleichschromatogramme zeigen, daß einige Hauptflavonoide in allen vier Rebenformen vorkommen; darüber hinaus unterscheiden sie sich jedoch durch zahlreiche weitere Spurenverbindungen. In Bestätigung bisheriger Arbeiten wurden als Hauptaglykone Quercetin und das in geringerer Konzentration vorliegende Kämpferol nachgewiesen. Bisher für die Reben nicht angegeben ist Myricetin, das in den von uns untersuchten Proben vorkommt. Zwei weitere Aglyka lassen sich derzeit noch nicht dünnschichtchromatographisch identifizieren.Alle Aglyka liegen in glykosidischer Bindung vor. Wir konnten bestätigen, daß Glucoside und Rhamnoglucoside in der Rebe vorliegen. Jedoch machen diese Verbindungen keineswegs die Hauptmasse der Glykoside in diesen Pflanzen aus. Die Hauptmenge des Quercetins und Kämpferols liegt in Form von Glucuroniden vor. Myricetin scheint allerdings nicht an der Glucuronid-Fraktion beteiligt zu sein. Es befindet sich im wesentlichen in der Glucosid-Fraktion. Die, Untersuchungen zur endgültigen Bestätigung dieser Befunde und zur Analyse weiterer Begleitsubstanzen werden fortgesetzt.Flavonol compounds in some members of the genus VitisThe flavonoid compounds of four vines (Vitis riparia, Vitis vinifera cvs. Riesling and Sylvaner, hybrid Sbl. 5-24-20) have been investigated. Beyond the known main aglycons quercetin and kaempferol we identified myricetin as a third component and showed the presence of two additional minor aglycons, which are not yet identified.All aglycons are present as glycosides. The glucosides and rhamnoglucosides of quercetin and kaempferol, described by other authors, and of myricetin are present, but ortly as minor components. The major amount of the flavonoids has been found as 3-glucuronides. The investigations will be continued

Monolayer Structure of Arachidic Acid on Graphite

Thomas LK, Kühnle A, Rode S, Beginn U, Reichling M. Monolayer Structure of Arachidic Acid on Graphite. Journal of Physical Chemistry C. 2010;114(44):18919-18924.The self-assembly of arachidic acid (C(19)H(39)COOH) at the liquid solid interface between 1-phenyloctane (C(6)H(5)(CH(2))(7)CH(3)) and highly oriented pyrolytic graphite (HOPG) is studied by scanning tunneling microscopy (STM) to identify the structure of the monomolecular film. We observe the formation of highly ordered domains with molecules oriented in three different orientations compatible with the symmetry of the HOPG substrate, a spontaneous enantiomeric separation of the pro-chiral molecules, and reveal structural details with submolecular resolution. To determine the surface unit cell with an intrinsic calibration to the substrate atomic structure, the intermolecular distance is precisely determined from the analysis of a SIN image exhibiting a moire pattern created by the superposition of current contributions from the molecular structure with contributions from the graphite atomic lattice. The dimensions of the unit cell accommodating two molecules are vertical bar a vertical bar 0.94 nm and vertical bar b vertical bar = 2.83 nm with an angle of 85 degrees between unit cell vectors a and h. The respective molecular arrangement allows hydrogen bonding between carboxylic groups with an unrelaxed O-O bond distance of 0.31 nm

Transition Radiation Spectroscopy with Prototypes of the ALICE TRD

We present measurements of the transition radiation (TR) spectrum produced in an irregular radiator at different electron momenta. The data are compared to simulations of TR from a regular radiator.Comment: 4 pages, 5 Figures, Proceedings for "TRDs for the 3rd millennium" (Sept. 4-7, 2003, Bari, Italy

Thermal Properties of Graphene, Carbon Nanotubes and Nanostructured Carbon Materials

Recent years witnessed a rapid growth of interest of scientific and engineering communities to thermal properties of materials. Carbon allotropes and derivatives occupy a unique place in terms of their ability to conduct heat. The room-temperature thermal conductivity of carbon materials span an extraordinary large range - of over five orders of magnitude - from the lowest in amorphous carbons to the highest in graphene and carbon nanotubes. I review thermal and thermoelectric properties of carbon materials focusing on recent results for graphene, carbon nanotubes and nanostructured carbon materials with different degrees of disorder. A special attention is given to the unusual size dependence of heat conduction in two-dimensional crystals and, specifically, in graphene. I also describe prospects of applications of graphene and carbon materials for thermal management of electronics.Comment: Review Paper; 37 manuscript pages; 4 figures and 2 boxe

The Depolarizing Action of GABA in Cultured Hippocampal Neurons Is Not Due to the Absence of Ketone Bodies

Two recent reports propose that the depolarizing action of GABA in the immature brain is an artifact of in vitro preparations in which glucose is the only energy source. The authors argue that this does not mimic the physiological environment because the suckling rats use ketone bodies and pyruvate as major sources of metabolic energy. Here, we show that availability of physiologically relevant levels of ketone bodies has no impact on the excitatory action of GABA in immature cultured hippocampal neurons. Addition of β-hydroxybutyrate (BHB), the primary ketone body in the neonate rat, affected neither intracellular calcium elevation nor membrane depolarizations induced by the GABA-A receptor agonist muscimol, when assessed with calcium imaging or perforated patch-clamp recording, respectively. These results confirm that the addition of ketone bodies to the extracellular environment to mimic conditions in the neonatal brain does not reverse the chloride gradient and therefore render GABA hyperpolarizing. Our data are consistent with the existence of a genuine “developmental switch” mechanism in which GABA goes from having a predominantly excitatory role in immature cells to a predominantly inhibitory one in adults

Gene expression profile and genomic alterations in colonic tumours induced by 1,2-dimethylhydrazine (DMH) in rats

<p>Abstract</p> <p>Background</p> <p>Azoxymethane (AOM) or 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats shares many phenotypical similarities with human sporadic colon cancer and is a reliable model for identifying chemopreventive agents. Genetic mutations relevant to human colon cancer have been described in this model, but comprehensive gene expression and genomic analysis have not been reported so far. Therefore, we applied genome-wide technologies to study variations in gene expression and genomic alterations in DMH-induced colon cancer in F344 rats.</p> <p>Methods</p> <p>For gene expression analysis, 9 tumours (TUM) and their paired normal mucosa (NM) were hybridized on 4 × 44K Whole rat arrays (Agilent) and selected genes were validated by semi-quantitative RT-PCR. Functional analysis on microarray data was performed by GenMAPP/MappFinder analysis. Array-comparative genomic hybridization (a-CGH) was performed on 10 paired TUM-NM samples hybridized on Rat genome arrays 2 × 105K (Agilent) and the results were analyzed by CGH Analytics (Agilent).</p> <p>Results</p> <p>Microarray gene expression analysis showed that <it>Defcr4</it>, <it>Igfbp5</it>, <it>Mmp7, Nos2, S100A8 </it>and <it>S100A9 </it>were among the most up-regulated genes in tumours (Fold Change (FC) compared with NM: 183, 48, 39, 38, 36 and 32, respectively), while <it>Slc26a3</it>, <it>Mptx</it>, <it>Retlna </it>and <it>Muc2 </it>were strongly down-regulated (FC: -500; -376, -167, -79, respectively). Functional analysis showed that pathways controlling cell cycle, protein synthesis, matrix metalloproteinases, TNFα/NFkB, and inflammatory responses were up-regulated in tumours, while Krebs cycle, the electron transport chain, and fatty acid beta oxidation were down-regulated. a-CGH analysis showed that four TUM out of ten had one or two chromosomal aberrations. Importantly, one sample showed a deletion on chromosome 18 including <it>Apc</it>.</p> <p>Conclusion</p> <p>The results showed complex gene expression alterations in adenocarcinomas encompassing many altered pathways. While a-CGH analysis showed a low degree of genomic imbalance, it is interesting to note that one of the alterations concerned <it>Apc</it>, a key gene in colorectal carcinogenesis. The fact that many of the molecular alterations described in this study are documented in human colon tumours confirms the relevance of DMH-induced cancers as a powerful tool for the study of colon carcinogenesis and chemoprevention.</p