New synthesis of 2-acyloxyimino-coumaranones

A New Synthesis of 2-Acyloxyimino-coumaranones The reaction of acetic anhydride with o-hydroxy-β-nitro-acetophenone does not yield 2-methyl-3-nitro-chromone, but 2-acetoxyimino-coumaranone (2-acetoxyimino-2,3-dihydrobenzofuranone-3). Other acid anhydrides give the same reaction; 2-benzoyloxyimino-, 2-veratroyloxyimino-and 2-(3,4-dibenzyloxy-benzoyloxyimino)-coumaranone were synthesized. Their degradation reactions and mass spectrometric fragmentations are discussed.     

The myocardiopathies of glycogenosis]

Thirty-three patients with glycogen abnormalities and myocardial disease were studied. 27 of them has type II glycogen disorders (Pompe's disease, with an intralysozymal deficit of acid maltase) and 6 with type III glycogen disorders Forbes disease, with a deficit in amylo-1-6-glucosidase). The picture of a type II abnormality in the infant is very standard: early onset, often neonatally; the association with asystole and muscular hypotonia and a characteristics clinical picture; invariable cardiomegaly and typical ECG findings (short PR interval, high voltage complexes). Death occurs before one year of age, treatment has limited effect, and attention is centred on the early discovery of heterozygotes and of diagnosis antenatally. The possibility of an obstructive type (4 out of 24) and a type with endocardial fibroelastosis (3 out of 24) must be emphasised. In the late onset myopathic form of type II disorder (3 cases), involvement of the myocardium is always found, but is of secondary importance in determining the clinical picture and natural history. The same can be said of type III disorders in which, despite the infrequency of asystole or significant cardiomegaly, a hypertrophic cardiomyopathy which may be obstructive can lead to sudden death in infancy (2 cases out of 6).     

Redoxpotentiale einiger 3′,4′-dihydroxylierter Flavon- und Flavonolderivate

The redox potentials of flavones with a free hydroxyl group at the 3-position have been determined by discontinuous titration to be significantly lower than those of flavones with an etherized, glycosidic linked or missing 3-hydroxyl group. Flavones and the flavonol derivatives without a free OH-group at the 3-position showed more positive potentials than catechol. Hydroxyl and methoxy groups at the 5-and 7-position have only a small influence on the redox potentials. Since the quinones formed by oxidation are unstable and polymerize easily, the potentials of the reaction solutions are not constant. The rate of change in potential is much smaller in the case of flavonols than of flavone derivatives without a free 3-hydroxyl group.     

Nucleotide induced head-head interaction in myosin

Summary In isolated myosin the reaction sequence of essential thiol groups with N-ethylmaleimide was studied using the following five approaches: kinetics of the modification reaction, effects of modification on enzyme properties, affinity chromatography of isolated subfragment-1 stemming from modified myosin, isolation of cyanogen bromide peptides and identification of the tryptic thiol peptides thereof. All techniques involved revealed differences whether the modification was performed in the presence or absence of pyrophosphate on the one hand and in the presence of ADP or ATP on the other. In the former cases the two thiol-1 groups per myosin, one per active site, reacted at an equal rate indicating an equivalent microenvironment of these groups and hence a symmetric site-site relationship. In contrast, the nucleotides induce the sequential modification of thiol-1 on one head followed by the thiol-2 on the other head. This indicates non-equivalence in microenvironment of the essential thiols connected with each active site and hence that a form of asymmetric head-head interaction is operative.     

When seeing depends on knowing: Adults with Autism Spectrum Conditions show diminished top-down processes in the visual perception of degraded faces but not degraded objects

Behavioural, neuroimaging and neurophysiological approaches emphasise the active and constructive nature of visual perception, determined not solely by the environmental input, but modulated top-down by prior knowledge. For example, degraded images, which at first appear as meaningless ‘blobs’, can easily be recognized as, say, a face, after having seen the same image un-degraded. This conscious perception of the fragmented stimuli relies on top-down priming influences from systems involved in attention and mental imagery on the processing of stimulus attributes, and feature-binding [Dolan, R. J., Fink, G. R., Rolls, E., Booth, M., Holmes, A., Frackowiak, R. S. J., et al. (1997). How the brain learns to see objects and faces in an impoverished context. Nature, 389, 596-599]. In Autism Spectrum Conditions (ASC), face processing abnormalities are well-established, but top-down anomalies in various domains have also been shown. Thus, we tested two alternative hypotheses: (i) that people with ASC show overall reduced top-down modulation in visual perception, or (ii) that top-down anomalies affect specifically the perception of faces. Participants were presented with sets of three consecutive images: degraded images (of faces or objects), corresponding or non-corresponding grey-scale photographs, and the same degraded images again. In a passive viewing sequence we compared gaze times (an index of focal attention) on faces/objects vs. background before and after viewers had seen the undegraded photographs. In an active viewing sequence, we compared how many faces/objects were identified pre- and post-exposure. Behavioural and gaze tracking data showed significantly reduced effects of prior knowledge on the conscious perception of degraded faces, but not objects in the ASC group. Implications for future work on the underlying mechanisms, at the cognitive and neurofunctional levels, are discussed.