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1.
J. Dierschke T. Krüger F. Hüttmann F. Bairlein Kerstin Müller G. Scheiffarth H. -W. Helb W. Irsch W. Lantermann B. Haubitz W. Winkel und J. Haffer 《Journal of Ornithology》2003,144(4):484-498
Ohne Zusammenfassung 相似文献
2.
Neurons in the visual cortex are responsive to the presentation of oriented and curved line segments, which are thought to act as primitives for the visual processing of shapes and objects. Prolonged adaptation to such stimuli gives rise to two related perceptual effects: a slow change in the appearance of the adapting stimulus (perceptual drift), and the distortion of subsequently presented test stimuli (adaptational aftereffects). Here we used a psychophysical nulling technique to dissociate and quantify these two classical observations in order to examine their underlying mechanisms and their relationship to one another. In agreement with previous work, we found that during adaptation horizontal and vertical straight lines serve as attractors for perceived orientation and curvature. However, the rate of perceptual drift for different stimuli was not predictive of the corresponding aftereffect magnitudes, indicating that the two perceptual effects are governed by distinct neural processes. Finally, the rate of perceptual drift for curved line segments did not depend on the spatial scale of the stimulus, suggesting that its mechanisms lie outside strictly retinotopic processing stages. These findings provide new evidence that the visual system relies on statistically salient intrinsic reference stimuli for the processing of visual patterns, and point to perceptual drift as an experimental window for studying the mechanisms of visual perception. 相似文献
3.
Anna Nilsson Thomas E. Fehniger Lena Gustavsson Malin Andersson Kerstin Kenne Gy?rgy Marko-Varga Per E. Andrén 《PloS one》2010,5(7)
Readouts that define the physiological distributions of drugs in tissues are an unmet challenge and at best imprecise, but are needed in order to understand both the pharmacokinetic and pharmacodynamic properties associated with efficacy. Here we demonstrate that it is feasible to follow the in vivo transport of unlabeled drugs within specific organ and tissue compartments on a platform that applies MALDI imaging mass spectrometry to tissue sections characterized with high definition histology. We have tracked and quantified the distribution of an inhaled reference compound, tiotropium, within the lungs of dosed rats, using systematic point by point MS and MS/MS sampling at 200 µm intervals. By comparing drug ion distribution patterns in adjacent tissue sections, we observed that within 15 min following exposure, tiotropium parent MS ions (mass-to-charge; m/z 392.1) and fragmented daughter MS/MS ions (m/z 170.1 and 152.1) were dispersed in a concentration gradient (80 fmol-5 pmol) away from the central airways into the lung parenchyma and pleura. These drug levels agreed well with amounts detected in lung compartments by chemical extraction. Moreover, the simultaneous global definition of molecular ion signatures localized within 2-D tissue space provides accurate assignment of ion identities within histological landmarks, providing context to dynamic biological processes occurring at sites of drug presence. Our results highlight an important emerging technology allowing specific high resolution identification of unlabeled drugs at sites of in vivo uptake and retention. 相似文献
4.
Lars Svennerholm Pam Fredman Birgitta Jungbjer Jan-Eric Månsson Britt-Marie Rynmark Kerstin Boström Bengt Hagberg Lars Norén Pirkko Santavuori 《Journal of neurochemistry》1987,49(6):1772-1783
Lipid composition was studied on cerebral tissue from nine children who had died of a progressive encephalopathy called the infantile form of neuronal ceroid lipofuscinosis (INCL) or polyunsaturated fatty acid lipidosis (PFAL). In the terminal stage of the disease, the concentrations of all lipid classes were found to be significantly reduced in the cerebral and cerebellar cortex and white matter. The concentration of gangliosides of the cerebral cortex was 15% and that of cerebrosides (galactosylceramide) in white matter 0.2-5% of the normal values for the children's ages. The reduction of gangliosides mainly affected those of the gangliotetraose series, particularly GD1a. The fatty acids of the linolenic acid series were strongly reduced in ethanolamine and serine phosphoglycerides. A very large increase up to 100-fold of oligoglycosphingolipids of the globo series and two fucose-containing lipids of the neolacto series was found in the forebrain of the three advanced cases examined. The brain tissue also contained very high concentrations of mono-, di-, and trisialogangliosides of the lacto and neolacto series, gangliosides with type 1 chain dominating. The structures of the gangliosides were tentatively identified by gas chromatography-mass spectrometry and monoclonal antibodies with carefully determined epitope specificity. The gangliosides and neutral glycosphingolipids had very similar fatty acid composition, consisting of about 40% stearic acid and 40% C24-acids. 相似文献
5.
6.
F Wunderlich M Helwig G Schillinger V Speth M F Wiser 《European journal of cell biology》1988,47(2):157-164
Erythrocytes infected with the malaria parasite Plasmodium chabaudi contain the neo-protein Pc90 in their plasma membrane. We investigate origin, membrane disposition, and intraerythrocytic traffic of this Pc90. Metabolic labeling of P.-infected erythrocytes, combined with cell fractionation as well as Western blot analysis and immunoprecipitation using a Pc90-recognizing monoclonal antibody, show that Pc90 is synthesized by early to mid trophozoites and is transported without any apparent processing steps to the erythrocyte membrane. Based upon the inaccessibility of Pc90 from the outside in intact erythrocytes and the water solubility of membrane-associated Pc90, it is concluded that Pc90 is localized on the cytoplasmic face of the host erythrocyte membrane. Immunoelectron microscopy using a Pc90-specific monoclonal antibody and the occurrence of soluble Pc90 in host cell cytosol indicate that the Pc90 is transported in both a 'vesicle-bound' and a 'free' form through the erythrocyte cytoplasm. 相似文献
7.
Replication of bovine papillomavirus vectors in murine cells 总被引:2,自引:0,他引:2
Margareta Waldenstrm Kerstin Schenstrm Kerstin Sollerbrant Lennart Hansson 《Gene》1992,120(2):175-181
8.
Kerstin Huss-Danell 《Plant and Soil》1986,91(1):43-49
Summary A pot experiment withAlnus incana (L.) Moench growing in sand was set up to compare the amounts of nitrogen released from plants shoot litter with that released below ground as root litter and/or root exudation. No nitrogen fixation by free-living microorganisms was found in the sand and the increased nitrogen content of the plant + soil system was therefore due to nitrogen fixation byFrankia in the alder root-nodules. Most of the nitrogen released from the plants was in the nitrogen-rich leaf and other shoot litter. Only small amounts of nitrogen were found in the drainage water from the pots and were recorded as increased nitrogen content of the sand. 相似文献
9.
Abstract The copy number of a pUB110 derivative, pKTH10, containing the α-amylase gene from Bacillus amyloliquefaciens , was determined, using an assay based on a sandwich hybridization technique. In this method, a known gene on the plasmid is hybridized between two non-overlapping fragments of that same gene, cloned into separate vectors. One fragment is used as a radiolabelled probe and the other bound to a filter, forming a three-component, 'sandwich' hybrid when the relevant gene is present in the sample. Since the hybridization can only take place in the presence of the relevant gene, the amount of radioactivity binding to the filters will be proportional to the concentration of this gene in the sample. We utilized the α-amylase gene on the plasmid to form the sandwich hybrid. The copy number was of a totally different magnitude from what has previously been reported, and ranged from 2500 copies/viable cell in early logrithimic growth phase to about 500 in late stationary phase. 相似文献
10.
Pharmacological profile of a novel carbacyclin derivative with high metabolic stability and oral activity in the rat 总被引:5,自引:0,他引:5
S Stürzebecher M Haberey B Müller E Schillinger G Schr?der W Skuballa G Stock H Vorbrüggen W Witt 《Prostaglandins》1986,31(1):95-109
A novel carbacyclin derivative (16S)-13,14-dehydro-16,20-dimethyl-3-oxa-18,18,19,19-tetradehydro- 6a- carbaprostaglandin-I2 (3-oxa-analogue) has been synthesized in order to find chemically and metabolically stable prostacyclin-mimetics with a potency equal or even superior to PGI2. The 3-oxa-analogue was found to be stabilized against beta-oxidation, a main metabolic degradation step also for chemically stable PGI2-analogues. The compound is orally available and displays a long duration of 4.5-48 h of antiaggregatory and hypotensive action. The 3-oxa-analogue inhibits ADP-induced platelet aggregation with an IC50 of 3.0 nM. Following intravenous application the 3-oxa-analogue lowers diastolic blood pressure in a dose dependent manner, the ED20 being 0.1-0.2 micrograms/kg after injection and less than or equal to 0.05 micrograms/kg/min after infusion respectively. In vivo platelet aggregation is inhibited after i.v. infusion of the 3-oxa-analogue with an IC50 of 0.037 micrograms/kg/min. As compared to Iloprost, the 3-oxa-analogue is 5-12 fold more potent with respect to in vivo hypotensive and anti-aggregatory effects. The results of the present studies indicate that the 3-oxa-analogue has a pharmacological profile comparable to prostacyclin (PGI2) and Iloprost. Due to the fact that the 3-oxa-analogue is chemically and metabolically stable, long term oral treatment can be achieved in clinical conditions in which PGI2 and Iloprost have already been shown to be therapeutically useful principles. 相似文献