Bitterstoffe beim Erhitzen von Prolin und Saccharose 3. Mitteilung

Zusammenfassung Die Konformation von 2,3-Bis-(1-pyrrolidinyl)-5-hydroxy-5-methyl-2-cyclopenten-1-on (I) wurde durch Röntgenstrukturanalyse ermittelt. Der Pyrrolidinring in Position 3 und der Cyclopentenonring sind um die C-N-Achse nur 10,2° gegeneinander gedreht und bilden ein nahezu planares System. Die beiden Pyrrolidinringe stehen dagegen in einem Winkel von 74,2° zueinander. Die resultierende sperrige hydrophobe Gruppierung wird als Ursache für den niedrigen Bitterschwellenwert von 1(0,02–0,04 mmol/1) angesehen. Die Schwellenwerte einiger anderer Aminohexosereduktone und Cyclopent(b)azepinone werden im Zusammenhang mit den Strukturen diskutiert.

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Bitter compounds obtained by heat treatment of proline and saccharose. III

Summary The conformation of 2,3-bis-(1-pyrrolidinyl)-5-hydroxy-5-methyl-2-cyclopenten-1-one (I) was determined by X-ray diffraction. The pyrrolidine ring in position 3 and the cyclopentenone ring are rotated around the N-C axis by only 10.2°, thus forming a nearly planar system. The two pyrrolidine rings, on the other hand, exhibit an angle of 74.2° relative to each other. The resulting bulky hydrophobic moiety is assumed to cause the low bitter threshold of 1 (0.02–0.04 mmol/1). The thresholds of some other aminohexose reductones and cyclo-pent(b)azepinones are discussed in relation to their structures.

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2. Mitteilung: Z Lebensm Unters Forsch (1985) 181:386     

SEarch via Recursive Rejection (SERR): Visual search for single and dual form-conjunction targets.

Models of visual search that assume spatially serial processing of conjunction stimuli break down when displays contain 2 identical conjunction targets: (1) They fail to account for the slopes of the target-absent reaction time (RT)/display size functions, both when the target-present response requires the detection of only 1 of the 2 targets and when it requires the detection of both targets, and (2) under redundant target conditions, the probability of "fast" present RTs is greater than that expected from the independent (serial) processing of the target stimuli. This article shows that G. W. Humphreys and H. J. Müller's (see record 1993-20216-001) parallel SERR model can account for human search performance under dual-target conditions. In SERR, simple form conjunctions are coded and grouped (on the basis of their similarity) in a spatially parallel manner, and targets are detected through the activation of a temporary "template" or through the recursive rejection of grouped distractors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sound and meaning in auditory data display

Auditory data display is an interdisciplinary field linking auditory perception research, sound engineering, data mining, and human-computer interaction in order to make semantic contents of data perceptually accessible in the form of (nonverbal) audible sound. For this goal it is important to understand the different ways in which sound can encode meaning. We discuss this issue from the perspectives of language, music, functionality, listening modes, and physics, and point out some limitations of current techniques for auditory data display, in particular when targeting high-dimensional data sets. As a promising, potentially very widely applicable approach, we discuss the method of model-based sonification (MBS) introduced recently by the authors and point out how its natural semantic grounding in the physics of a sound generation process supports the design of sonifications that are accessible even to untrained, everyday listening. We then proceed to show that MBS also facilitates the design of an intuitive, active navigation through "acoustic aspects", somewhat analogous to the use of successive two-dimensional views in three-dimensional visualization. Finally, we illustrate the concept with a first prototype of a "tangible" sonification interface which allows us to "perceptually map" sonification responses into active exploratory hand motions of a user, and give an outlook on some planned extensions.     

Shear stress inhibits H2O2-induced apoptosis of human endothelial cells by modulation of the glutathione redox cycle and nitric oxide synthase

Physiological levels of shear stress reduce endothelial cell turnover and exert a potent antiatherosclerotic effect. Here we demonstrate that oxidative stress-induced apoptosis of human endothelial cells was inhibited by shear stress exposure (15 dynes/cm2). Incubation with H2O2 (200 mumol/L) for 18 hours induced apoptosis of human umbilical venous endothelial cells as demonstrated by an enzyme-linked immunosorbent assay specific for histone-associated DNA fragments and visual analysis of fluorescence-stained nuclei. Shear stress-mediated inhibition of apoptosis was partially prevented by pharmacological inhibition of glutathione (GSH) biosynthesis with buthionine sulfoximine (BSO) or nitric oxide (NO) synthase with NG-monomethyl-L-arginine (LNMA), whereas inhibition of catalase by aminotriazol did not affect the inhibitory action of shear stress. Combined inhibition of NO synthase and GSH biosynthesis completely reversed the protective effect of shear stress, suggesting that both NO synthase and the GSH redox cycle system are involved in the apoptosis-suppressing effect of shear stress. Similar results were obtained when apoptosis was stimulated by tumor necrosis factor alpha (TNF alpha). To gain further insights into the interference of shear stress with apoptosis signal transduction, we measured caspase-3-like activity, a cysteine protease that has been shown to play a predominant role in the cell death effector pathway. Indeed, shear stress prevented the activation of caspase-3-like activity induced by H202 or TNF alpha. The inhibitory effect of shear stress was prevented by LNMA and BSO, suggesting that the reduction of oxidative flux by shear stress prevents the activation of caspase-like proteases and thereby inhibits apoptotic cell death in human endothelial cells.     

Antipodean squint

Strabismic cases which are exotropic fixing with one eye, and esotropic fixing with the other eye are rare and a result of anisometropia, unequal accommodation, paresis or restriction, and previous ocular muscle surgery. Three cases of antipodean squint are reported without known etiology factor. An extensive survey of experts in the field of strabismus was unable to document other similar cases where a cause could not be determined.