Biomedical subjects

Sarah Leonard

Publications and source records attributed to Sarah Leonard.

3 recordsLinked to original sources

PubMed2004

Dissociation between the Espinet and perceptual learning effects in flavour aversion conditioning.

In three experiments rats were given pre-exposure to two compound flavours, AX and BX, the two compounds being presented for some subjects on alternate trials (the intermixed schedule) and, for others, in separate blocks of trials (the blocked schedule). After aversion conditioning with A (in Experiments 1 and 2), the inhibitory properties of B were tested using both retardation (Experiment 1) and summation tests (Experiment 2). The results failed to support the proposal [Anim. Learn. Behav. 23 (1995) 361] that B should acquire inhibitory properties in the intermixed condition (the "Espinet effect"). Experiment 3 demonstrated that generalisation to BX after conditioning with AX was attenuated by intermixed pre-exposure (a perceptual learning effect). This pattern of results challenges the hypothesis that inhibitory learning during intermixed pre-exposure to AX and BX can account for both the Espinet and the perceptual learning effects.

Animals↗

PubMed2004

The successes and challenges of developing a prison telepsychiatry service.

Prisoners are not typical of the general population with regard to their health needs, as they have a disproportionately high incidence of mental health problems and drug misuse. Health-care delivery in prison faces a significant number of challenges not experienced by other health-care organizations. Telepsychiatry is one strategy to improve the accessibility and quality of mental health-care in the prison setting. Despite some initial challenges, a telepsychiatry service was successfully established between a medium-secure unit in Fareham, Hampshire, and a category B training prison on the Isle of Wight. A low-cost, PC-based videoconferencing system was used, connected by ISDN lines at 128 kbit/s. A valuable lesson that was learnt was the importance of having the support of key individuals in a prison setting.

Delivery of Health Care↗

PubMed2002

Structure-activity relationship for enhancement of paracellular permeability across Caco-2 cell monolayers by 3-alkylamido-2-alkoxypropylphosphocholines.

Paracellular permeability enhancers have been used to improve the oral bioavailability of hydrophilic drugs; however, the mechanism of action of many enhancers is poorly understood. In this study, highly potent enhancers of paracellular permeability were identified in the 3-alkylamido-2-alkoxypropylphosphocholine series, and a structure-activity relationship was developed for enhancement of paracellular permeability across Caco-2 cell monolayers. Compounds with short (<5 carbons) hydrocarbon chains at both C-2 and C-3 were generally inactive. The potency exhibited a parabolic relationship with respect to the chain length at either C-2 or C-3. Linear molecules (i.e., compounds with a short hydrocarbon chain at C-2 or C-3 and a long hydrocarbon chain on C-3 or C-2, respectively) were more potent than the corresponding branched molecules with the same carbon load. The efficacy of 3-alkylamido-2-alkoxypropylphosphocholines as enhancers of paracellular permeability was not dependent on their existence in micellar form or their ability to alter the fluidity of cell membrane. Previously, a correlation between the potency of alkylphosphocholines as enhancers of paracellular permeability and the inhibitors of phospholipase C (PLC) was established in Madine Darby canine kidney (MDCK) cell monolayers. The potencies of selected 3-alkylamido-2-alkoxypropylphosphocholines as inhibitors of PLC and enhancers of paracellular permeability fit well into this correlation. Therefore, phosphocholines are likely to increase paracellular permeability by modulating the signal transduction pathway initiated by a PLC-catalyzed reaction rather than by physically altering the cell membrane.

Adenosine Triphosphate↗