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J Vian

Publications and source records attributed to J Vian.

11 recordsLinked to original sources
PubMed1997

Stereospecific in vitro and in vivo effects of the new sinus node inhibitor (+)-S 16257.

The effects of the two isomers, (+)-S 16257 and (-)-S 16260, of a new bradycardic agent, (+/-)-S 15544 (7,8-dimethoxy 3-[3-[[(4.5-dimethoxybenzocyclobutan-1-yl)methyl] methylamino]propyl]1,3,4,5-tetrahydro-2H-3-benzazepin-2-one), were compared in vitro and in vivo on cardiac spontaneous rate and repolarization time. In the isolated rabbit sino-atrial node, the three compounds (3 microM) were equi-effective to reduce the action potential firing rate. In anesthetized pigs, both isomers (0.03, 0.1, 0.3 and 1 mg kg(-1) i.v.) were equipotent to reduce heart rate. For all compounds, the negative chronotropic effect resulted from a reduction in the slope of diastolic depolarization of pacemaker cells. In sino-atrial node cells, (-)-S 16260 (3 microM) increased action potential duration while (+)-S 16257 had a smaller effect. In driven guinea-pig papillary muscles exposed to increasing concentrations of compounds (0.1 to 10 microM) a small prolongation of action potential duration was observed. This prolongation was more marked in rabbit Purkinje fibers stimulated at a low rate. In all cardiac preparations the highest prolongation was observed with (-)-S 16260. In vivo, (-)-S 16260 prolonged QTc at the two highest doses tested while (+)-S 16257 had no effect. In conclusion, resolution of (+/-)-S 15544 into its two enantiomers yielded compounds with the same bradycardic effects. Of the isomers, (+)-S 16257 has an increased specificity with minimal direct effect on action potential repolarization.

Action Potentials↗
PubMed1995

Functional correlates of dopamine D3 receptor activation in the rat in vivo and their modulation by the selective antagonist, (+)-S 14297: 1. Activation of postsynaptic D3 receptors mediates hypothermia, whereas blockade of D2 receptors elicits prolactin secretion and catalepsy.

Using [125I]-iodosulpride as a radioligand, the novel naphthofurane, (+/-)-S 11566 [(+/-)-[7-(N,N-dipropylamino)-5,6,7,8-tetra-hydro- naphtho(2,3b)dihydro,2,3-furane]) showed a marked preference for human, recombinant D3 as compared with D2 receptors stably transfected into Chinese hamster ovary cells (Kis = 24/529 nM). This activity resided in its (+)-eutomer, (+)-S 14297 (13/297 nM) as compared with its (-)-distomer, (-)-S 17777 (406/3544 nM). In contrast, (+)-AJ 76 manifested only a mild 2-fold preference for D3 sites (70/154 nM), whereas haloperidol and six additional antagonists showed a mild (2-7-fold) preference for D2 sites. As concerns agonists, (+)-7-OH-DPAT, (+/-)-CGS 15855A, quinelorane, (-)-quinpirole and N-0434 displayed a preference (6-40-fold) for D3 receptors, whereas piribedil showed a slight, 2-fold, preference for D2 sites (243/126 nM). (+)-S 14297 showed low (> 1.0 microM) affinity at rat D1 and D2 sites and at cloned, human D4 and D5 receptors and only low affinity (145 to > 10,000 nM) at all other sites examined. In vivo, administered s.c., (+)-7-OH-DPAT, CGS 15855A, quinelorane, (-)-quinpirole and N-0434 potently evoked hypothermia. Across all (8) agonists tested, potency correlated significantly with affinity at D3 sites (r = .84, P < .001) but not D2 sites (r = .50, P > .05). (+)-S 14297 (0.16-1.25 mg/kg, s.c.) blocked the induction of hypothermia by (+)-7-OH-DPAT, CGS 15855A and (-)-quinpirole, but not by the alpha 2-adrenergic agonist, clonidine, without influencing core temperature alone. In contrast, (-)-S 17777 (10.0 mg/kg, s.c.) was only partially active. Across all (9) antagonists, potency for inhibition of (+)-7-OH-DPAT-induced hypothermia correlated more strongly with affinity at D3 (r = .96, P < .001) than D2 (r = .75, P < .02) sites. Whereas haloperidol and the other antagonists provoked prolactin secretion and elicited catalepsy, (+)-S 14297 and (+/-)-S 11566 at doses of up to 10.0 and 40.0 mg/kg, s.c., respectively, were not significantly effective (P > .05). Across all antagonists, potency for eliciting prolactin secretion and catalepsy correlated better with affinity at D2 (r = .95 and .96) than D3 (r = .76 and .91) sites. In conclusion, these data demonstrate that the novel naphtofurane, (+)-S 14297, is a selective ligand (antagonist) at dopamine D3 receptors and suggest that their activation mediates hypothermia in the rat.(ABSTRACT TRUNCATED AT 400 WORDS)

2-Naphthylamine↗
PubMed1995

Functional correlates of dopamine D3 receptor activation in the rat in vivo and their modulation by the selective antagonist, (+)-S 14297: II. Both D2 and "silent" D3 autoreceptors control synthesis and release in mesolimbic, mesocortical and nigrostriatal pathways.

The preferential dopamine (DA) D3 versus D2 receptor agonist, (+)-7-OH-DPAT, dose-dependently decreased DA synthesis in the nucleus accumbens, olfactory tubercles, striatum and frontal cortex. This action was potently mimicked by several other high-potency D3 agonists: CGS 15855A, (-)-quinpirole, quinelorane and N-0434. In contrast, piribedil, which displays a mild preference for D2 sites, was less active. Across eight agonists, potency for inhibition of DA synthesis correlated more potently to affinity at D3 (r = .82 +/- .04) than D2 receptors (r = .60 +/- .06, P < .05). Correlations were also marked to potency for induction of a further D3-mediated response, hypothermia (r = .93 +/- .02). The novel and selective D3 versus D2 antagonist, (+/-)-S 11556, attenuated the action of (+)-7-OH-DPAT in each structure. This action was shared by its active (+)-eutomer, (+)-S 14297, whereas its inactive (-)-distomer, (-)-S 17777, was ineffective. (+)-S 14297 similarly attenuated the inhibitory action of CGS 15855A and (-)-quinpirole upon DA synthesis, whereas it failed to modify inhibition of striatal DA synthesis by the alpha 2-adrenergic receptor agonist, clonidine. As compared with the D2/D3 receptor antagonist, haloperidol, neither (+/-)-S 11566 nor (+)-S 14297 modified DA turnover upon administration alone. Furthermore, across (nine) antagonists, potency in facilitating DA synthesis more powerfully correlated to affinity at D2 (r = .94 +/- .01) than D3 (r = .73 +/- .01) sites (P < .01). Correlations were also marked to potency for induction of catalepsy (r = .91 +/- .01) and prolactin secretion (r = .89 +/- .01) but not for antagonism of (+)-7-OH-DPAT-induced hypothermia (r = .60 +/- .01). In freely moving rats, (+)-7-OH-DPAT dose-dependently reduced dialysate concentrations of DA in the nucleus accumbens and contralateral striatum: this action was potently mimicked by CGS 15855A, but only weakly so by piribedil. (+)-S 14297 markedly attenuated the action of (+)-7-OH-DPAT, whereas (-)-S 17777 was inactive. In contrast, haloperidol completely blocked the action of (+)-7-OH-DPAT. Finally, in distinction to haloperidol, upon administration alone, (+)-S 14297 did not significantly enhance the release of DA. In conclusion, these data suggest that D3 (auto)receptors control synthesis and release of DA in dopaminergic pathways innervating the limbic system, cortex and striatum.(ABSTRACT TRUNCATED AT 400 WORDS)

2-Naphthylamine↗
PubMed1994

S 14297, a novel selective ligand at cloned human dopamine D3 receptors, blocks 7-OH-DPAT-induced hypothermia in rats.

The selective dopamine D3 receptor agonist, 7-OH-DPAT ((+)-7-hydroxy-2-(di-n-propylamino)tetralin) and the novel naphthofurane, S 14297 ((+)-[7-(N,N-dipropylamino)-5,6,7,8-tetrahydro- naphtho(2,3b)dihydro,2,3-furane]), bound with high affinity and selectivity to recombinant, human dopamine D3 versus D2 receptors stably transfected into Chinese hamster ovary cells: Ki values = 2 versus 103 nM for 7-OH-DPAT and 13 versus 297 nM for S 14297. In contrast, the putative dopamine D3 receptor antagonist, AJ 76 (cis-(+)-5-methoxy-1-methyl-2-(n- propylamino)tetralin), displayed low affinity and selectivity for dopamine D3 versus D2 sites (70 versus 154 nM). 7-OH-DPAT (0.01-0.16 mg/kg s.c.) provoked hypothermia in rats, an action abolished by S 14297 (0.04-0.63 mg/kg s.c.) and, less potently, by AJ 76 (0.16-2.5 mg/kg s.c.). S 14297 (20.0 mg/kg s.c.) did not modify prolactin secretion. These data suggest that dopamine D3 receptors mediate hypothermia in the rat and that S 14297 acts as a selective antagonist at these sites.

2-Naphthylamine↗
PubMed1994

Electrophysiological effects of S 16257, a novel sino-atrial node modulator, on rabbit and guinea-pig cardiac preparations: comparison with UL-FS 49.

1. S 16257 is a new bradycardic agent. Its electropharmacological profile has been compared to that of the known bradycardic compound UL-FS 49 (Zatebradine). Intracellular recordings of action potentials (APs) were performed with conventional glass microelectrodes. 2. In the rabbit isolated sino-atrial node (SAN) tissue, S 16257 and UL-FS 49 (1 microM, 3 microM and 10 microM) were equipotent in slowing spontaneous APs firing predominantly by decreasing the rate of diastolic depolarization (at 3 microM, -23.8 +/- 3.9% and -27.9 +/- 2.6%, respectively). For the two compounds a maximal effect was obtained at 3 microM. In these preparations, action potential duration at 50% of total repolarization (APD50) was more affected by UL-FS 49 than S 16257 at any concentration tested (at 3 microM, +8.9 +/- 2.9% and +29.1 +/- 3.7% for S 16257 and UL-FS 49, respectively; P < or = 0.01). 3. To estimate the direct effects on AP duration, driven cardiac preparations were exposed to these agents. In guinea-pig papillary muscles, paced at a frequency of 1 Hz, increasing concentrations of S 16257 or UL-FS 49 (0.1 to 10 microM, 30 min exposure for each concentration) slightly prolonged AP repolarization. This prolongation was more marked for UL-FS 49 (at 1 microM, +6.1 +/- 0.6% and +11.2 +/- 1.3% elevation of APD50, for S 16257 and UL-FS 49, respectively). 4. Application of UL-FS 49 (3 microM) to rabbit Purkinje fibres, triggered at a frequency of 0.25 Hz, induced a marked prolongation of APD50 and APD90 (+149.4 +/- 51.2% and +86.0 +/- 15.4%, respectively). S 16257 (3 MicroM) induced only a weak prolongation of AP (+ 14.1 +/- 5.0% and + 14.8 +/- 3.3% for APD50 and APD90, respectively) significantly smaller than in the case of UL-FS 49.5. These results show that S 16257 slows the rate of spontaneous AP firing in isolated SAN mainly by a reduction of the diastolic depolarization of the cells, which suggests an inhibition of the pace-maker current (If). S 16257 and UL-FS 49 are equipotent in their bradycardic effect but S 16257 is more specific as it induces less increase in myocardial repolarization time.

Action Potentials↗
PubMedDate not supplied

Analysis of nurse-doctorates; data collected for the International Directory of Nurses with Doctoral Degrees.

In an American Nurses' Foundation survey of the 1973 population of nurses with doctoral degrees (N = 1,020) general trends in doctoral education of nurses were elicited. Specific unique characteristics were highlighted, including: a continuing trend for nurses to earn the Ph.D. rather than the Ed.D., a divergence between field of doctoral study and the current field of research interest, and a slight number of these qualified nurses actually participating in research of any kind. The majority of subjects were single; most were employed in a university or college where they held either full or associate professorships; most considered themselves still to be in the field of nursing, although their doctoral studies frequently took them out of the discipline; their work responsibilities were heavily loaded with administrative duties. As compared with the holders of doctoral degrees in other fields, nurses earned their degrees later, but took no longer to complete them. While universities in the Mid-Atlantic states were the largest producers of nurse-doctorates, universities in the Midwest were found to be the most frequent employers. Questions regarding the future direction of nurse-doctorates were raised.

Adult↗