Discriminating experiments

Based on the modest ability of the (+)-isomers of MDMA and MBDB to inhibit the reuptake of norepinephrine (NE) into hypothalamic synaptosomes (Steele et al. 1987). it seemed possible that noradrenergic pathways might be involved in the eue. In ano er series of drug discrimination experiments designed to test this hypothesis, the specific NE uptake inhibitor (-)-tomoxctine was tested for stimulus transfer in doses up to 10 mg/kg in MDMA-trained rats. At 5 mg/kg, 67 percent of the animals responded on, the drug lever. However, pretreatment with tomoxetine in six rats trained to discriminate MDMA from saline had no effect on the discrimination of a subsequent dose of MDMA. 

Stolerman IP (1989) Discriminative stimulus effects of nicotine in rats trained under different schedules of reinforcement. Psychopharmacology 97 131-138 Stolerman IP (1991) Measures of stimulus generalization in drug discrimination experiments, Behav Pharmacol 2 265-282... 

Stolerman IP, Garcha HS (1989) Temporal factors in drag discrimination experiments with nicotine. J Psychopharmacol 3 88-97... 

This concept was also applied to a discrimination experiment with 2-fluoro- and 4-fluoroisobutyrophenone [64]. Thus, treatment of an equimolar mixture of 2-fluoro-and 4-fluoroisobutyrophenone in toluene at -78 °C with MesAl (1 equiv.) and subsequent addition of tributyltin hydride resulted in formation of two different alcohols 51 and 52 (82 % combined yield) in a ratio of 34 1. Here again, the discrimination capacity is dramatically reduced by using other Lewis acids (Sch. 37). 

An important historic development was the insight that surface tension is a surface- and not a bulk-property. Newton ) had already discriminated between cohesive and adhesive forces. A decisive discriminative experiment was carried out by Hawksbee ). He investigated liquid rise in capillaries and between glass plates and found that the thickness of the glass did not matter. So the phenomenon of wetting was established as a surface phenomenon, although the depth of the interactions responsible for the various tensions still remains an issue today (chapter 2). 

Different approaches were used to distinguish between the signals of guest and host molecules. In single-pulse experiments (SPEs), with a relatively short delay of 8-10 s, only solvent C resonances were monitored (Fig. 20a, and top trace Fig. 20c,). This so-called T discrimination experiment takes advantage of the significant distinction of the spin-lattice relaxation times of the mobile... 

Rate acceleration provided by the chelate formation was further observed in a discrimination experiment between two isomeric alkoxycarbonyl compounds 36 and 37 (X = OMe R =Pr or H) as shown in Table 1-9 (entries 1-4). Thus, chelation-induced selective reduction of a-methoxyisobutyrophenone 36 (X=OMe R =Pr ) was observed to furnish o-methoxyphenyl carbinol 38 (X = OMe R =Pr R = H) preferentially with (C6F5)3B and Me3Al. The (CfiF5)3B and Me3Al-pro-moted discriminative allylation of an equimolar mixture of o- and p-anisaldehyde,... 

Overall, these experimental results indicate that (1) urinary odors of individuality in rats and mice are influenced by dietary factors and genetic differences at the major histocompatibility complex (2) the presence of bacteria is necessary for the appropriate expression of both of these cues and (3) methodological factors may influence the outcome of odor discrimination experiments. 

Each "age group" was further divided into five subgroups. Prior to egg discrimination experiments, the females from each subgroup were isolated from their eggs for 0, 24, 48, 72, or 96 h, respectively. 

Table 4. F values and probabilities for group main effects in eight independent odor discrimination experiments. 

Twelve saccharides were selected for the discrimination experiment D-ribose, D-arabinose, L-rhamnose, D-xylose, D-lyxose, D-glucose, D-mannose, D-galactose, D-fructose, L-sorbose, melibiose, and lactulose. The selected saccharides all possess free hydroxy groups in the 1- and 2-position allowing them to bind to the boronic acid. The increase in fluorescence intensity [F/Fq) induced by adding the saccharide to the BBV/HPTS sensing ensemble was measured with a fluorescence plate reader (Figure 5.23). 

High-resolution C spectra of solid polymers can principally be obtained by two ways from normal Bloch decays (SPE single-pulse excitation) of the carbon magnetisation, just as in 1-NMR, or from cross-polarisation. These techniques are complementary. Discriminating experiments may consist of comparing CP/MAS and SPE spectra (the latter obtained without cross-polarisation). Whereas the former depends on proton relaxation, the latter is affected only by carbon relaxation. Because of the great segmental mobility in elastomers, these systems have shorter spin-lattice relaxation times (in the order of seconds), which makes SPE feasible. 

Proton relaxation data allow the NMR spectroscopist both to interpret CPMAS spectra and to devise discriminating experiments [20]. One such... 

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