Search results for "toxin"
showing 10 items of 1434 documents
Differentiation of Penicillium griseofulvum Dierckx isolates by enzyme assays and by patulin and griseofulvin analyses
1990
The production of patulin and griseofulvin by 49 different isolates of Penicillium griseofulvum Dierckx was analyzed by high-performance liquid chromatography. Eleven isolates were obtained from pistachio nuts, 37 were obtained from wheat seeds, and 1 was obtained from the American Type Culture Collection. Activities of 19 enzymes were also assayed by the API ZYM system. From these results it may be deduced that there are two different groups among the strains tested which cannot be distinguished by morphological and cultural characteristics. One group of isolates did not produce detectable amounts of patulin and griseofulvin when grown in sucrose-yeast extract and Wickerham media, while en…
Mycotoxin Incidence in Some Fish Products: QuEChERS Methodology and Liquid Chromatography Linear Ion Trap Tandem Mass Spectrometry Approach
2019
The inclusion of vegetal raw materials in feed for fish farming has increased the risk of mycotoxin occurrence in feed, as well as in edible tissues from fish fed with contaminated feed, due to the carry-over to muscle portions. Therefore, the objective of this study was to evaluate the occurrence of 15 mycotoxins in processed fish products, which are commonly consumed, such as smoked salmon and trout, different types of sushi, and gula substitutes. A QuEChERS method was employed to perform the mycotoxin extraction from fish samples. For mycotoxin identification and quantitation, the selected technique was the liquid chromatography-tandem mass spectrometry linear ion trap (LC-MS/MS-LIT). Sm…
Novel Analogs and Stereoisomers of the Marine Toxin Neodysiherbaine with Specificity for Kainate Receptors
2007
Antagonists for kainate receptors (KARs), a family of glutamategated ion channels, are efficacious in a number of animal models of neuropathologies, including epilepsy, migraine pain, and anxiety. To produce molecules with novel selectivities for kainate receptors, we generated three sets of analogs related to the natural marine convulsant neodysiherbaine (neoDH), and we characterized their pharmacological profiles. Radioligand displacement assays with recombinant alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and KARs demonstrated that functional groups at two positions on the neoDH molecule are critical pharmacological determinants; only binding to the glutamate receptor …
Dual effect mediated by protease-activated receptors on the mechanical activity of rat colon
2002
1. The present study examined the mechanical effects of agonist enzymes and receptor-activating peptides for protease-activated receptor (PAR)-1 and PAR-2 on longitudinal and circular muscle of rat isolated colonic segments in the attempt to clarify the PAR functional role in intestinal motility. 2. The responses to PAR-1 and PAR-2 activation were examined in vitro by recording simultaneously the changes of endoluminal pressure (index of circular muscle activity) and of isometric tension (index of longitudinal muscle activity). 3. Both PAR-1 agonists, thrombin (0.1 nM - 3 microM) and SFLLRN-NH2 (1 nM - 3 microM), and PAR-2 agonists, trypsin (0.1 nM - 10 microM) and SLIGRL-NH2 (1 nM - 10 mic…
Role of NK1 and NK2 receptors in mouse gastric mechanical activity
2006
The aim of the present study was to examine the role of NK1 and NK2 receptors in the control of mechanical activity of mouse stomach. In this view, the motor effects induced by NK1 and NK2 receptor agonists and antagonists were analyzed, measuring motility as intraluminal pressure changes in mouse-isolated stomach preparations. In parallel, immunohistochemical studies were performed to identify the location of NK1 and NK2 receptors on myenteric neurons and smooth muscle cells. Substance P (SP) induced biphasic effects: a contraction followed by relaxation; neurokinin A (NKA) and [β-Ala8]-NKA(4−10), selective agonist of NK2 receptors, evoked concentration-dependent contractions, whereas [Sar…
Arachidonic acid relaxes human pulmonary arteries through K+ channels and nitric oxide pathways.
2004
We aimed to investigate the role of K(+) channels and nitric oxide (NO) on the relaxant effects of arachidonic acid in the human intralobar pulmonary arteries. Arachidonic acid produced a concentration-dependent relaxation (E(max)=93+/-3% of maximal relaxation induced by papaverine 0.1 mM;-log EC(30)=7.03+/-0.09) that was antagonized by the cyclooxygenase inhibitor indomethacin (1 microM), by the combination of cyclooxygenase blockade and cytochrome P450 (CYP) blockade with 17-octadecynoic acid (17-ODYA, 10 microM), by the combination of cyclooxygenase inhibition and NO synthase (NOS) inhibition with N(omega)-nitro-l-arginine (l-NOARG, 100 microM), by the simultaneous inhibition of CYP and …
Isoform specificity of cardiac glycosides binding to human Na+,K+-ATPase α1β1, α2β1 and α3β1
2009
Abstract Cardiac glycosides inhibit the Na + ,K + -ATPase and are used for the treatment of symptomatic heart failure and atrial fibrillation. In human heart three isoforms of Na + ,K + -ATPase are expressed: α 1 β 1 , α 2 β 1 and α 3 β 1 . It is unknown, if clinically used cardiac glycosides differ in isoform specific affinities, and if the isoforms have specific subcellular localization in human cardiac myocytes. Human Na + ,K + -ATPase isoforms α 1 β 1 , α 2 β 1 and α 3 β 1 were expressed in yeast which has no endogenous Na + ,K + -ATPase. Isoform specific affinities of digoxin, digitoxin, β-acetyldigoxin, methyldigoxin and ouabain were assessed in [³H]-ouabain binding assays in the abse…
Über «therapeutische» und «toxische» Digitoxigeninwirkungen auf elektrophysiologische Messgrössen des Meerschweinchenvorhofs
1963
‘Therapeutic’ concentrations of digitoxigenin (10−7−3× 10−7 g/ml), producing positive inotropic effects, did not alter resting and action potentials of electrically driven guinea-pig auricles. However, ‘toxic’ concentrations of digitoxigenin (5 × 10−7−10−8 g/ml), producing arrhythmias and contracture of the myocardium, had a marked influence upon resting and action potentials and conduction velocity.
�ber die Wirkung von Strophanthidin-3-bromacetat am Papillarmuskel des Meerschweinchens
1971
In experiments on isolated, electrically stimulated papillary muscles or auricles of guinea pig hearts some characteristics of the inotropic action of strophanthidin-3-bromaocetate (SBA), a derivative of k-strophanthidin which is supposed to be an irreversible inhibitor of the (Na+-K+)-activated ATPase, were studied and compared with the behaviour of k-strophanthidin and digitoxin.
Die Reversibilität der Wirkung von Digitoxin, Strophanthidin und Strophanthidin-3-bromazetat am Papillarmuskel und einer mikrosomalen Na+-K+-aktivier…
1969
The reversibility of the inhibitory action of strophanthidin, strophanthidin-3-bromoacetate, and digitoxin on the Na+-K+-ATPase activity (microsomal fraction, guinea-pig brain) was compared with the rate of decline of their positive inotropic effects (papillary muscle, guinea-pig heart) after exposure to drug-free solution. The actions of strophanthidin and digitoxin were easily reduced on both systems. Strophanthidin-3-bromoacetate, however, was found to have an irreversible blocking effect on the transport ATPase, whereas its inotropic action could be rapidly abolished.