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Biomedical subjects

J S Ward

Publications and source records attributed to J S Ward.

At least 55 records · Page 3Linked to original sources
PubMed1992

The inhibitory effects of cromakalim and its active enantiomer BRL 38227 against various agonists in guinea pig and human airways: comparison with pinacidil and verapamil.

The effects of the potassium channel activators, cromakalim, BRL 38227 and pinacidil, and the calcium antagonist, verapamil, have been compared against various spasmogens on airway responses in vitro and in vivo in the guinea pig and also in human isolated bronchi. In guinea pig tracheal spirals, potassium channel activators generally had a greater inhibitory effect than verapamil against tone induced by a wide range of spasmogens (spontaneous, 5-hydroxytryptamine, leukotriene D4, prostaglandin E2). The potassium channel activators had very little effect against potassium chloride- and carbachol-induced tone in guinea pig tracheal spirals [e.g., cromakalim (20 microM) induced relaxations of 0.21 +/- 0.03 (relative to an isoprenaline maximum = 1.0, mean +/- S.E.M.) against carbachol, compared to 0.77 +/- 0.03 against histamine]. In vivo, the potassium channel activators prevented histamine and 5-hydroxytryptamine-induced bronchoconstrictions, but had little inhibitory effect against acetylcholine. In contrast, in human bronchi, cromakalim was capable of inducing powerful concentration-dependent relaxations against carbachol-induced tone [cromakalim (20 microM) induced relaxations of 0.77 +/- 0.09 (relative to isoprenaline = 1.0, mean +/- S.E.M.) against carbachol, compared to 0.95 +/- 0.04 against histamine]. In human bronchi, all the inhibitory agents were more potent and more effective, except that verapamil did not have an increased maximum response. We conclude that potassium channel activators should be effective at relaxing contractions induced by a wide range of spasmogens in man.

Animals↗
PubMed1990

Interactions between scopolamine and muscarinic cholinergic agonists or cholinesterase inhibitors on spatial alternation performance in rats.

The effects on working memory of the muscarinic cholinergic agonists oxotremorine, arecoline, RS86 and pilocarpine, and the cholinesterase inhibitors physostigmine and tetrahydroaminoacadine were investigated in male F344 rats. Working memory was assessed by behavior maintained under a spatial alternation schedule of food presentation in which the interval between trials was varied from 2 to 32 sec. Under control conditions the percentage of correct responses decreased as the retention interval was varied from 2 to 32 sec. Administered alone the cholinergic agonists oxotremorine (0.01-0.1 mg/kg), arecoline (3-30 mg/kg), RS86 (0.3-3 mg/kg) and pilocarpine (0.3-3.0 mg/kg), and the cholinesterase inhibitors physostigmine (0.01-0.1 mg/kg) and tetrahydroaminoacridine (0.3-3.0 mg/kg) either had no effect on or produced dose-related deficits in working memory and decreases in response rates. The muscarinic antagonist scopolamine (0.1 mg/kg) produced retention interval-dependent decreases in the percentage of correct responding and rates of responding. The cholinergic agonists and tetrahydroaminoacridine failed to reverse the effects of scopolamine. However, physostigmine produced a dose-dependent reversal of the working-memory deficits and response-rate decreasing effects of scopolamine. The present results are consistent with the interpretation that drugs which primarily enhance M2 muscarinic cholinergic transmission are ineffective in enhancing working memory or in reversing scopolamine-induced deficits in working memory.

Animals↗
PubMed1989

Decreased 5-hydroxytryptamine turnover in striatum and other brain regions after administration of 5-methoxy-3-(di-n-propylamino)chroman to rats.

5-Methoxy-3-(di-n-propylamino)chroman (5-MeO-DPAC) caused a dose-dependent decrease in the accumulation of 5-hydroxytryptophan after decarboxylase inhibition in rat striatum, hippocampus and frontal cortex. The decreased 5-hydroxytryptamine (5-HT) turnover may have resulted from activation of 5-HT receptors on cell bodies of 5-HT neurons that project to the striatum and other brain regions, since 5-MeO-DPAC had earlier been reported to lack affinity for striatal binding sites.

5-Hydroxytryptophan↗
PubMed1988

Ergolines as selective 5-HT1 agonists.

The synthesis and serotonin receptor subtype affinity of a series of ergolines are described. High selectivity for the 5-HT1 subtype was found with a number of 8-substituted (3 beta, 5 beta)-9,10-didehydro-6-methylergolines. The more potent and selective of these compounds increased the concentration of serotonin and decreased the concentration of 5-HIAA in rat brain and increased corticosterone concentration in rat serum. Oral administration of 13, (3 beta)-2,3-dihydrolysergine, produced long-lasting decreases in serotonin turnover. Compound 13 lacked substantial dopaminergic activity as measured by its effects on dopamine turnover in whole brain or striatum and its affinity for alpha-adrenergic binding sites was significantly less than for 5-HT1 binding sites. The increases in serum corticosterone concentrations produced by 13 were not blocked by the serotonin uptake inhibitor fluoxetine or by the serotonin synthesis inhibitor p-chlorophenylalanine, suggesting that 13 exerts its effects through direct stimulation of serotonin receptors.

Animals↗
PubMed1977

A study of ergonomics factors in washbasin design.

A 4-week UNESCO-sponsored mission to the Department of Architecture, Karadeniz Technical University in Eastern Turkey, gave an opportunity to apply ergonomics techniques to some aspects of that country's domestic washbasin design. The study was intended to provide experience in questionnaire design and administration, in the application of psycho-physical methods, and to highlight the importance of determining user characteristics and preferences with regard to the built environment. A field study elicited information on dimensions and positioning of existing wash-basins and ancillary equipment and the opinions of users as to the suitability of these features in relation to the activities performed. A laboratory study, using an adjustable rig permitting variation in the heights of basin, taps and mirror/shelf, followed. The data obtained on preferred heights of these items led to the conclusions that basin height should be increased to between 95 and 100 cm to satisfy the majority of users; tap height above the basin should be reduced to about 11 cm; the shelf and lower edge of a mirror sited above the basin should be 136 cm above the floor; and a clear space of 110 cm should be available between the front of the basin and a wall or other obstruction. Suggestions on other design aspects of the bathroom, resulting from the study, are discussed.

Journal Article↗
PubMed1970

Ergonomics in the home.

The house and housework are as appropriate an area of ergonomics study as in the factory floor, but much less concerted effort has been put into studying the problems of the housewife. It is suggested that investigations to determine the amount of physiological effort (particularly that of muscle activity by techniques such as electromyography), the optimum dimensional accord between equipment and user, and the provision of satisfactory environmental conditions, are needed in order to ensure that the housewife performs her tasks with the minimum of unnecessary effort and maximum satisfaction.

Journal Article↗