Massenspektroskopie von Naturstoffen. I. Vergleichende Anionen-Kationen-Massenspektroskopie von 2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosylestern

Mass Spectroscopy of Natural Compounds. I. Comparative Investigation of Anion-Cation Mass Spectra of 2,3,4,6-Tetra-O-acetyl-β-D-glucopyranosyl Esters The electron attachment mass spectra (anion mass spectra) of 2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl esters with different structures of the acids are discussed and compared with the corresponding electron impact spectra. In contrast to the cation mass spectra the molecular ion peak appears in all the anion mass spectra.     

Diesel exhaust particles modulate the tight junction protein occludin in lung cells in vitro

Background  

Using an in vitro triple cell co-culture model consisting of human epithelial cells (16HBE14o-), monocyte-derived macrophages and dendritic cells, it was recently demonstrated that macrophages and dendritic cells create a transepithelial network between the epithelial cells to capture antigens without disrupting the epithelial tightness. The expression of the different tight junction proteins in macrophages and dendritic cells, and the formation of tight junction-like structures with epithelial cells has been demonstrated. Immunofluorescent methods combined with laser scanning microscopy and quantitative real-time polymerase chain reaction were used to investigate if exposure to diesel exhaust particles (DEP) (0.5, 5, 50, 125 μg/ml), for 24 h, can modulate the expression of the tight junction mRNA/protein of occludin, in all three cell types.     

Alternating Current Electrophoretic Deposition of Antibacterial Bioactive Glass-Chitosan Composite Coatings

Alternating current (AC) electrophoretic deposition (EPD) was used to produce multifunctional composite coatings combining bioactive glass (BG) particles and chitosan. BG particles of two different sizes were used, i.e., 2 μm and 20–80 nm in average diameter. The parameter optimization and characterization of the coatings was conducted by visual inspection and by adhesion strength tests. The optimized coatings were investigated in terms of their hydroxyapatite (HA) forming ability in simulated body fluid (SBF) for up to 21 days. Fourier transform infrared (FTIR) spectroscopy results showed the successful HA formation on the coatings after 21 days. The first investigations were conducted on planar stainless steel sheets. In addition, scaffolds made from a TiAl4V6 alloy were considered to show the feasibility of coating of three dimensional structures by EPD. Because both BG and chitosan are antibacterial materials, the antibacterial properties of the as-produced coatings were investigated using E. coli bacteria cells. It was shown that the BG particle size has a strong influence on the antibacterial properties of the coatings.     

Growth points in research on memory and hippocampus.

We present an overview of two of our ongoing projects relating processes in the hippocampus to memory. We are trying to understand why retrograde amnesia occurs after damage to the hippocampus. Our experiments establish the generality of several new retrograde amnesia phenomena that are at odds with the consensus view of the role of the hippocampus in memory. We show in many memory tasks that complete damage to the hippocampus produces retrograde amnesia that is equivalent for recent and remote memories. Retrograde amnesia affects a much wider range of memory tasks than anterograde amnesia. Normal hippocampal processes can interfere with retention of a long-term memory stored outside the hippocampus. We conclude that the hippocampus competes with nonhippocampal systems during memory encoding and retrieval. Finally, we outline a project to understand and manipulate adult hippocampal neurogenesis in order to repair damaged hippocampal circuitry to recover lost cognitive functions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Detection of leukocytes in contact with the vessel wall from in vivo microscope recordings using a neural network

Leukocytes play an important role in the host defense as they may travel from the blood stream into the tissue in reacting to inflammatory stimuli. The leukocyte-vessel wall interactions are studied in post capillary vessels by intravital video microscopy during in vivo animal experiments. Sequences of video images are obtained and digitized with a frame grabber. A method for automatic detection and characterization of leukocytes in the video images is developed. Individual leukocytes are detected using a neural network that is trained with synthetic leukocyte images generated using a novel stochastic model. This model makes it feasible to generate images of leukocytes with different shapes and sizes under various lighting conditions. Experiments indicate that neural networks trained with the synthetic leukocyte images perform better than networks trained with images of manually detected leukocytes. The best performing neural network trained with synthetic leukocyte images resulted in an 18% larger area under the ROC curve than the best performing neural network trained with manually detected leukocytes.     

The dual function of the proliferating cell nuclear antigen (PCNA) in the response of human cells to UV damages

An auxiliary protein of DNA polymerases delta and epsilon, the proliferating cell nuclear antigen (PCNA), is necessary for efficient DNA replication in vivo and in vitro, and also for the repair synthesis in vitro, but its role in the excision repair of genome in vivo is not exactly established. In S-phase of unirradiated cells, PCNA is tightly bound to focal centers of DNA replication and is not removed by treatment with detergent Triton X-100, but is completely extracted from non-S-phase cells by the indicated detergent. It was shown earlier that after UV-irradiation PCNA could not be removed by the detergent even from non-S-phase cells. It was interpreted as the evidence of PCNA integration into the repair complex and of the participation of this protein in repair synthesis in vivo. In the present work the data were obtained indicating that the role of PCNA in cell response to UV-damage was not confined only to its possible involvement in repair synthesis. With the help of confocal microscopy it was established that in Triton X-100-extracted normal cells PCNA did not colocalize with the well known excision repair protein XPB/ERCC3, defective in cells from Xeroderma pigmentosum (complementation group B) patients. XPB-protein is induced by UV-irradiation in normal cells, and this induction is not observed in repair deficient cells. However, in such cells UV-light induces a detergent-resistant form of PCNA, and this form is obviously not connected with repair. It cannot be excluded that a rapid PCNA immobilization immediately after UV-irradiation of cells is needed for the facilitation of photochemical damage bypass during the subsequent replication of genome.     

Lipid patches in membrane protein oligomers: crystal structure of the bacteriorhodopsin-lipid complex

Heterogenous nucleation on small molecule crystals causes a monoclinic crystal form of bacteriorhodopsin (BR) in which trimers of this membrane protein pack differently than in native purple membranes. Analysis of single crystals by nano-electrospray ionization-mass spectrometry demonstrated a preservation of the purple membrane lipid composition in these BR crystals. The 2.9-A x-ray structure shows a lipid-mediated stabilization of BR trimers where the glycolipid S-TGA-1 binds into the central compartment of BR trimers. The BR trimer/lipid complex provides an example of local membrane thinning as the lipid head-group boundary of the central lipid patch is shifted by 5 A toward the membrane center. Nonbiased electron density maps reveal structural differences to previously reported BR structures, especially for the cytosolic EF loop and the proton exit pathway. The terminal proton release complex now comprises an E194-E204 dyad as a diffuse proton buffer.     

Electron-beam CT-angiography in abdominal aortic aneurysms. Initial results

PURPOSE: To evaluate the suitability of ultrafast electron-beam tomography (EBT) for the investigation of abdominal aortic aneurysms using CTA. METHODS: Thirty-one patients with suspected abdominal aortic aneurysm were investigated with EBT using an Evolution XP scanner (Siemens, Erlangen) with the newest software version 12.34 with continuous volume scanning of 140 images in 17 s. Collimation was 3 mm, table increment 4 mm with overlapping image reconstruction every 2 mm, exposure time 200 ms (124 mAs), resulting in a scan-range of 28 cm. A quantity of 80 ml contrast material was administered (flow 4 ml/s). Visualization of the abdominal aorta and its branches was performed with MIPs and shaded surface display. Evaluation of image quality was based on a four-step classification scale (1 = good, 4 = insufficient) for the demonstration of the abdominal aorta and the visceral, renal and iliac arteries. RESULTS: All EBT examinations demonstrated high and homogeneous density values along the whole vessel course with a mean density value of 258.7 +/- 47.3 HU for the abdominal aorta and the iliac arteries. Quality evaluation for the vessel demonstration showed mean values between 1.22 and 1.57 for the abdominal aorta and the visceral, renal and iliac arteries. CONCLUSIONS: EBT with 140 slices and slice reconstruction every 2 mm offers a high z-axis resolution resulting in high-quality CT angiographies of the whole abdominal aorta and its branches.     

Cilioretinal arteries. A study based on review of stereo fundus photographs and fluorescein angiographic findings

The incidence of cilioretinal arteries in 2,000 eyes of 1,000 consecutive patients was determined by review of stereo color fundus photographs and fluorescein angiographs. One or more cilioretinal arteries were present in 49.5% of all patients or in 32.1% of the eyes. The arteries occurred bilaterally in 14.6% and contributed to some portion of the macular circulation in 18.7% of the patients. A great deal of variability of size, number, and distribution of cilioretinal vessels was observed. Prior studies that were based on direct visualization of the fundus have reported cilioretinal arteries in 7% to 29.6% of patients examined. Careful review of stereo fundus photographs and early phase fluorescein angiographs aided in the observation of these vessels that might otherwise have been unrecognized. We believe the method of review accounts for the high incidence of cilioretinal arteries in our series.     

Radio frequency sputtering of CdSe films

We have studied the influence of various substrate and sputtering parameters on the electrical and structural properties of CdSe films. The most important deposition parameters are the substrate temperature and the plasma power density. The condensation rate is determined by both parameters. The power density not only determines the arrival rate of the condensing species on the substrate but (which is even more important for the film quality) it also controls the substrate bombardment by energetic particles (secondary electrons and ions). This bombardment apparently has a big influence on the condensation rate and the structural ordering of the growing film.The film growth was investigated on two different substrates, namely basal- plane-oriented sapphire and silica glass. At substrate temperatures below 400°C the film properties on both kinds of substrates are approximately equal. These films are polycrystalline with a large degree of preferred (0001) orientation (the c axis perpendicular to the substrate). At substrate temperatures above 400°C the mechanism of film growth on the two different substrates is vastly different. The CdSe films on amorphous silica glass become increasingly amorphous with increasing substrate temperature or plasma power density. On the other hand the films on single-crystal sapphire become epitaxial with increasing substrate temperature. The epitaxial relation between substrate and film is as expected, namely (0001) CdSe_∥ on (0001) Al₂O₃.