Avoidance active

Cycloaddition reactions often require the use of harsh conditions such as high temperatures and long reaction times. These conditions are not compatible with sensitive reagents or products such as natural products. The applicability of Diels-Alder cycloadditions is, moreover, limited by the reversibility of the reaction when a long reaction time is required. The short reaction times associated with microwave activation avoid the decomposition of reagents and products and this prevents polymerization of the diene or dienophile. All these problems have been conveniently solved by the rapid heating induced by microwave irradiation, a situation not accessible in most classical methods. With the aid of microwave irradiation, cydoaddition reactions have been performed with great success [9, 10]. 

Philippens IHCHM, Melchers BPC, Wolthuis OL. Active avoidance in guinea pigs, effects of physostigmine and scopolamine. Pharmacol. Biochem. Behav. 42 285-289, 1992. 

Modifying your evening activities — avoiding beverages, stimulating activities, and caffeine in the evening. 

For all phototrophic organisms exposed to UV radiation for substantial parts of their life cycles, strategies that passively screen UV radiation will contribute to preventing UV-induced direct and indirect damage to essential biomolecules. In addition, UV-screening may also save metabolic energy by reducing the need for constantly active avoidance and repair processes. 

Mactutus CF, Tilson HA. 1984. Neonatal chlordecone exposure impairs early learning and retention of active avoidance in the rat. Neurobehav Toxicol Teratol 6(1 ) 75-83. 

Ginseng extract improves the spatial learning performance of aged rats in an eight-arm radial maze and operant discrimination task (Nitta et al. 1995). It also improves memory performance in active-avoidance (shuttle-box) and passive-avoidance (step-down) tasks, and reinforces staircase-maze learning in both young and aged rats. (Petkov and Mosharrof 1987 Petkov et al. 1990 Petkov et al. 1992). The effects were also very dose dependent, with inverted U-shape dose-response curves. 

Am I alert to and actively avoiding escalation of commitment to a failing course of action ... 

Xu Z, Seidler FJ, et al (2002) Adolescent nicotine administration alters serotonin receptors and cell signaling mediated through adenylyl cyclase. Brain Res 951(2) 280-292 Xu Z, Seidler FJ, et al (2003) Sex-selective hippocampal alterations after adolescent nicotine administration effects on neurospeciflc proteins. Nicotine Tob Res 5(6) 955-960 YUmaz O, Kanit L, et al (1997) Effects of nicotine on active avoidance learning in rats sex differences, Behav Pharmacol 8(2-3) 253-260... 

Acetylcholinesterase, 308-309 Acid, 462, 463,471-474, 477 Action-outcome relationship, 304 Active avoidance learning, 279 Addiction, 209-229 Additives, 459, 465, 469,472, 473 Adolescent, 424 25... 

The influence of chain length and side-chain modifications of ACTH-derived peptides on active avoidance behaviour in rats will be discussed. H-Met(02)-Glu-His--Phe-D-Lys-Phe-OH (Org 2766) emerged from these studies as an orally active peptide with an increased potency and selectivity of action. Physico-chemical data (from the literature) on the reference peptide ACTH--(4-10) did not point to a preferred conformation in solution, whereas in the crystalline state an antiparallel 3-pleated sheet structure was found. At the receptor site we suggested an a-helical conformation in which the Phe and Met residues are close together. Additional support for this suggestion came from the behavioural activity of [des-Tyr", Met ]enkephalin and of cyclo--(-Phe-Met-cAhx-), eAhx merely serving as a spacer. 

The relationship between the structure of a series of peptides derived from the adrenocorticotropic hormone ACTH, and the behavioural activity in an active avoidance behaviour test, has been studied over the past 10-20 years. The results obtained were quite different from those in which endocrine activity relationships were studied. From the outcome of a quantitative study on the structure--behavioural activity of the ACTH-related peptides, suggestions about the spatial interactions at the receptor site were made. This receptor-bound conformation differed from those suggested by solution experiments or found in crystal structures. 

The first step in these studies has been the search for the shortest fragment of the ACTH chain that is essential for (maintenance of) activity. Next, changes in the peptide backbone and modification of the side-chains of the amino acid residues have been studied. As a test system the delay of extinction of an active avoidance response in rats as measured in a pole-jumping test after subcutaneous administration has been used (7 ) this assay method gives a graded dose-response relationship which allows the estimation of an ED50 and thus potency ratio s. The heptapeptide ACTH--(4-10) has been used as the reference peptide (8 ). For a more extensive review see ref. 9. 

If in instrumental conditioning a response is not followed by a punishment, but its absence, animals will increase this response in order to minimise punishment. In active avoidance tasks, for instance, animals have to show a distinct behavioural response in order to avoid a punishment. Typical examples would be shuttle-box experiments and jump-up avoidance. A shuttle box consists of two compartments that are connected by a sliding door. The punishment will be signalled by either a tone or a light stimulus (CS). Animals have to leave the compartment in which the CS was presented within a selected amoimt of time, after which the CS would be followed by a footshock. In the pole-jump test, the occurrence of the footshock will be signalled by a tone or hght stimulus as well. Animals can avoid the punishment if they jump onto a vertical wooden rod. 

Further studies are needed to characterize the mechanisms underlying AVP over-expression and over-release in more detail. The same holds true for the hyper- and hypo-emotional Roman low- and high-avoidance rats, originally selected and bred for poor versus rapid acquisition of two-way active avoidance response (Steimer and Driscoll 2003). In the former, more ACTH and corticosterone were secreted upon a mild stressor, again indicating a hyper-reactive HPA axis. This was shown to be associated with higher AVP mRNA levels in the PVN, whereas CRH mRNA did not differ between the hnes (Aubry et al. 1995). 

Impair or enhance the performance of rats in an active avoidance task [V. Paul et al. 1994 Petkov et al. 1995]... 

J Am Acad Child Adolesc Psychiatry 28 856-860, 1989 Ogren S-O Forebrain serotonin and avoidance learning behavioural and biochemical studies on the acute effect of p-chloroamphetamine on one-way active avoidance learning in the rat. Pharmacol Biochem Behav 16 881-895, 1982 Ogren S-O Central serotonin neurons in avoidance learning interactions with noradrenaline and dopamine neurons. Pharmacol Biochem Behav 23 107-124, 1985... 

Quartermain D, Clement J, Schemer A 5-HT, agonists disrupt memory of fear conditioning in mice. Biol Psychiatry 33 247-254, 1993 Quartermain D, Clement J, Schemer A The 5-HT, agonist tandospirone disrupts retention but not acquisition of active avoidance learning. Pharmacol Biochem Behav 48 805-807, 1994... 

Strains selected for differences in learning performance Roman high avoidance (RHA) versus Roman low avoidance (RLA). In addition to the different performances displayed on the acquisition of an active avoidance task (RHA > RLA rats) these two strains have been described to differ in emotionality/level of anxiety (RHA < RLA) (e.g. Gentsch et t//., 1988). 

For compounds that require metabolic activation, avoiding structural features that may provide resonance stabilization of electrophilic metabolites (e.g., conjugated double bonds, or conjugated system/aryl moiety) will decrease the lifetime of the reactive intermediates. 

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