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Chiral synthesis of a component of Amanita muscaria, (-)-4-hydroxypyrrolidin-2-one and assessment of its absolute configuration
No full textConvenient synthesis of stereospecifically deuteriated glycines from glutamic acid using a combination of enzymatic and chemical methods
No full textChiral glycines (1a) and (1b) have been synthesized starting from stereospecifically deuteriated 4-aminobutanoic acids (3a) and (3b). Enzymatic decarboxylation of (2S)-glutamic acid (2a) in 2H2O and (2R,S)-[2,4,4-2H3]glutamic acid (2b) + (2c) in H 2O afforded (3a) and (3b), respectively. Chemical transformations of deuteriated pyrrolidinones (4a) and (4b) afforded stereospecifically labelled glycines (1a) and (1b) in good yields
Synthesis of (R)- and (S)-2-aminobutane from (S)- and (R)-2-aminobutanol
No full text(R)-(-)- and (S)-(+)-2-Aminobutane (1) can be synthesized in good yield and high optical purity from (S)-(+)- and (R)-(-)-2-aminobutanol (2) respectively
Afferent sympathetic unmyelinated fibres with left ventricular endings in cats
No full text1. We recorded the electrical impulse activity of thirty-three single afferent fibres with left ventricular endings from the third and fourth left thoracic sympathetic rami communicantes of anaesthetized cats. Their conduction velocity ranged from 0.23 to 0.98 m/sec (group C). 2. The endings of each fibre were localized to the left ventricle by mechanical probing performed at the end of the experiment on the non-beating heart. No fibre had multiple sensory fields. 3. The impulse activity (0.95 +/- 0.2 impulses/sec) was spontaneous but most often a fixed temporal correlation between impulses and ventricular dynamics was not detectable. It was increased during occlusion of the thoracic aorta, I.V. administration of isoprenaline or infusion of saline. It was unaffected by asphyxia, haemorrhage and I.V. administration of acetylcholine. It was decreased during occlusion of inferior vena cava. Therefore these ventricular receptors appeared to be mainly sensitive to mechanical events. 4. The fibres were excited during the occlusion of the left main coronary artery, after a latency of 14.5 +/- 1.3 sec. They were also excited during ventricular fibrillation, exhibiting the highest values of impulse activity (2.51 +/- 0.4 impulses/sec). The increase in impulse activity during ventricular fibrillation was sometimes immediate and extreme, with peak frequencies of about 50 impulses/sec. 5. These spontaneously active ventricular receptors with unmyelinated nerve fibres participate in the transmission of the continuous impulse activity which from the cardiovascular system reaches the spinal cord through the sympathetic nerves and which is likely to contribute to the neural control of circulation. Thus the unmyelinated cardiac sympathetic afferents should not be considered as purely nociceptive in function
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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