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Acute effects of aflatoxins on guinea pig ileum
No full textPrevious studies on the aflatoxins have focused mainly on their chronic toxic effects. In this study we investigated the acute gastrointestinal effects of four common aflatoxins on isolated guinea pig ileum. AFB(1) (EC(50) 4.6+/-0.4 microM) and AFB(2) (EC(50)17+/-4.4 microM) contracted isolated guinea pig ileum in a dose-dependent manner, whereas AFG(1) and AFG(2) evoked no contractions. Atropine (5.9 nM 11.8 and 23.6 nM) antagonized AFB(1)-induced contractions in a dose-dependent manner. Pretreatment with the nicotinic ganglionic blocker, hexamethonium (up to 55 microM), left AFB(1)-induced contractions unchanged. In contrast, tetrodotoxin (0.3 microM), blocked AFB(1) contractile activity. The two inhibitors of ACh release, morphine (0.3 microM) and clonidine (0.4 microM), antagonized EC(50) AFB(1)-induced contractions, and apamin, a drug that increases neuronal excitability, facilitated the EC(50) AFB(1)-induced contractile effect. The choline uptake blocker, hemicholinium (17.4 microM) markedly reduced AFB(1)-induced contractions. These results suggest that aflatoxins induce their contractile effect indirectly through the cholinergic system by stimulating acetylcholine release from the postganglionic parasympathetic nerve endings. The acute actions of aflatoxins on isolated guinea pig ileum could explain their acute gastrointestinal effects in humans and animals
Antibacterial activity of Hydrastis canadensis extract and its major isolated alkaloids
No full textThe antibacterial activity of extract and isolated ma- jor alkaloids (berberine, b-hydrastine, canadine and canadaline) of Hydrastis canadensis L. (Ranunculaceae) was evaluated against 6 strains of microorganism: Staphylococcus aureus (ATCC 25993 and ATCC 6538P), Streptococcus sanguis (ATCC 10556), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853). Bactericidal activity was evaluated by contact test by measuring the akilling timeo on a low density bacterial inoculum, and bacteriostatic activity in liquid medium by M.I.C. values. The results provide a rational basis for the traditional antibacterial use of Hydrastis canadensis
Isolation of secoiridoids artifacts from Lonicera japonica.
No full textTwo artifactual secoiridoid glucosides werw isolated from a butanol extract of Lonicera japonica
Studies on vasoconstrictor activity of Curculigo pilosa extract and of its isolated compounds
No full textThe Curculigo pilosa total extract, its butanolic fraction (0.5 microg-100 mg/kg) and the most active in vitro compound structurally similar to adrenaline, pilosidine (10 ng-l mg/kg), caused a reversible and dose-dependent increase in blood pressure in anaesthetized rat. This hypertensive effect is partially reversed (90%) by the prior administration of phentolamine (1 mg/kg) and abolished by pre-treatment with phentolamine (1 mg/kg) and atenolol (100 microg/kg). Neither tachiphylaxis nor any toxic effects were observed. These experimental findings suggest an interaction between C. pilosa and the peripheral adrenergic system (particularly with alpha1 and beta1 receptors); the structure of the bioactive glucosides could be important in evoking this effect
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
Benzylbenzoate and norlignan glucosides from Curculigo pilosa: structural analysis and in vitro vascular activity
No full textFrom the rhizomes of Curculigo pilosa, two benzylbenzoate diglucosides, piloside A and piloside B, and a glucosyl-fused norlignan, pilosidine, previously obtained only as the tetra-O-methyl derivative, were isolated. Pilosidine showed facilitating effect on adrenaline evoked contractions in rabbit aorta isolated preparations. (C) 2000 Elsevier Science Ltd. All rights reserved
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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