Action mode/mechanism

Mechanism of Action. The mechanisms by which antibiotic adrninistration at subtherapeutic levels enhance growth rate and efficiency of gain in growing animals have not been clarified. Possible modes of action include disease control, nutrient sparing, and metaboHc effects. There is extensive evidence that the principal benefit from subtherapeutic use of antibiotics results from the control of harmfiil microorganisms. 

Thijssen, H.H.W. (1995). Warfarin-based rodenticides mode of action and mechanism of resistance. Pesticide Science 43, 73-7S. 

Stages in hazard characterization according to the European Commission s Scientific Steering Committee are (1) establishment of the dose-response relationship for each critical effect (2) identification of the most sensitive species and strain (3) characterization of the mode of action and mechanisms of critical effects (including the possible roles of active metabolites) (4) high to low dose (exposure) extrapolation and interspecies extrapolation and (5) evaluation of factors that can influence severity and duration of adverse health effects. 

In cooperation with USDA-ARS, isolated compounds demonstrating phytotoxic activity will be synthesized and tested to determine lethal concentrations, mode of action, and mechanism of action. 

His major scientific interests are bacterial virulence and various aspects of bacteriocins and toxins including quorum sensing regulation, mode of action, and mechanisms involved in immunity and receptor targeting. 

Currently, there are no validated and regulatory accepted in vitro methods for assessing repeated dose toxicity. Numerous in vitro systems have been developed over the last decades and have been discussed and summarized in recent ECVAM reports on repeated dose toxicity testing (Worth and Balls 2002, Prieto et al. 2005, Prieto et al. 2006). Human in vitro data, particularly on kinetics and metabolism, and in vitro test data from well-characterized target organ and target system models on, e.g., mode of action(s)/mechanism(s) of toxicity may be useful in the interpretation of observed repeated dose toxicity. 

A constant observation when the MRP were separated by various methods was that antioxidative effect was found in many different fractions. Both the dialysates and the retentates from dialysis were antioxidative to some extent. All the electrophoresis fractions exhibited some antioxidative effect. Attempts to separate the MRP by column chromatography on Sephadex G-50 have resulted in several fractions with some antioxidative effect, and so on. This indicates that several antioxidative products are formed by the Maillard reaction, possibly differing in molecular size and chemical structure, but perhaps with one single antioxidative functional group in common, such as a free radical function. However, it can not be excluded that the MRP contain a few entirely different antioxidants with different modes of action. Various mechanisms have also been suggested. Eichner (6) claimed MRP to inactivate the hydroperoxides formed by the lipid oxidation. There are also reports on the complex binding of metals by MRP (18, 19). 

Vitamins are essential in mammalian physiology because their coenzyme forms are prosthetic groups or cofactors in many enzyme reactions or because they can perform certain specialized functions in the human organism. Vitamin A and its role in the visual process is an example. The biology of vitamins may be examined from the nutritional or biochemical points of view. The former is concerned with minimum daily requirements, dietary sources, bioavailability, and deficiency syndromes. The biochemist looks for structures, functional groups, conversion to coenzymes, mechanisms of action, mode of transport, and storage. Both aspects will be addressed in this chapter, though the emphasis will be on the biochemical properties of vitamins. 

Mode of action Several mechanisms have been identified by which chloroquine kills the organism after accumulating in the organism. 

Bozdogan B, Appelbaum PC. Oxazolidi-nones activity, mode of action, and mechanism of resistance. Int. J. Antimi-crob. Agents, 2004, 23, 113—119. 

Even for antimicrobial drugs wich have the same mode of action, the mechanisms of actions in molecular terms can be quite different. An instructive example of this is the body of knowledge on actions of inhibitors of protein synthesis at the ribosomal level66). Since the mechanistic details of protein biosynthesis as well as of DNA replication are still incompletely resolved, studies on mechanisms of action of inhibitors of these biosynthetic processes frequently remain inconclusive when the target reaction is not known. Each problem of the mechanism of action of a chemotherapeutic drug becomes an individual research problem in its own right, after the mode of action has been elucidated in the manner described in this article. 

The quality and consistency of the data are important. Evaluation of substances or mixtures related to the material being classified should be included, as should site of action and mechanism or mode of action study results. Both positive and negative results are assembled together in a single weight of evidence determination. 

Toxicokinetic studies in animals and humans, site of action and mechanism or mode of action study results may provide relevant information, which could reduce or increase concerns about the hazard to human health. If it can be conclusively demonstrated that the clearly identified mechanism or mode of action has no relevance for humans or when the toxicokinetic differences are so marked that it is certain that the hazardous property will not be expressed in humans then a substance which produces an adverse effect on reproduction in experimental animals should not be classified. 

Modes of action The mechanisms of UDCA and its effects in cholestatic liver diseases are not yet fully understood - even though a number of different effects have been demonstrated. These include (i.) hepatopro-tective (92, 97, 98), (2.) cytoprotective (89), and (3.) biliary-metabolic effects (84, 93, 104, 105), as well as (4.) an influence on the immune system. In ligature of the bile duct in rats, UDCA was found to reduce the occurrence of histological changes and biliary cirrhosis as well as of portal hypertension. (98) (s. tab. 40.7)... 

For many of the commonly used anti-protozoal drugs the modes of action and mechanisms of selective toxicity are well understood, although for some the precise mechanism remains unclear. The most... 

The role of cytoskeletal tubulins in the mode of action and mechanism of drug resistance to benzimidazoles has been reviewed by Lacey [111], who also supports the above hypothesis proposing a close relationship between tubulin-microtubules and other sites of the benzimidazole action. It is believed that inhibition of glucose uptake, fumarate-reductase activity or neuromuscular activity are dependent on inhibition of polymerisation of tubulins to microtubules by benzimidazoles. The inhibition of tubulins by benzimidazoles is so pronounced that it is postulated that even the hatching of eggs of H. controtus is a microtubule dependent process [240]. 

Mode of action or mechanism of action (MOA) studies are performed to characterize the interaction of an active compound with its target in detail in order to understand how the compound... 

Beeslow, R. (1962), Part 11. Cocarboxylase Mode of action, reaction mechanism, and role of the active acetate, Ann. N. Y. Acad. Sci. 98, 445-452. 

Vial, H. J., and Calas, M. (2001). Inhibitors of phospholipid metabolism. In "Antimalarial Chemotherapy, Mechanisms of Action, Modes of Resistance and New Directions in Drug Development" (Rosenthal, ed.), pp. 347-365. Humana, Totowa, NJ. 

Mode of Action, Resistance Mechanism and New Targets Control of Insect... 

F. E. Dayan, S. O. Duke, Phytotoxidty of Protoporphyrinogen Oxidase Inhibitors Phenomenology, Mode of Action and Mechanisms of Resistance, in Herbicide Activity Toxicology, Biochemistry and Molecular... 

Compounds shown in Table 12.17 entered the market only recently or are going to enter soon. Because the mode of action and mechanism of resistance are still unknown, these compounds have been given a transient status. As soon as more detailed information becomes available, these compounds will be given a... 

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