(PACE 2017; 40:425-433) ablation, arrhythmia, fluoroless

Binding competition between endogenous dopamine (DA) and the D2 receptor radiotracer [123I]IBZM allows measurement of the change in synaptic DA following amphetamine challenge with SPECT in the living human brain. Previous investigations using this technique in healthy subjects have shown that the magnitude of amphetamine effect on [123I]IBZM binding potential (BP) is small (range between 5 to 15% decrease), and that a large between-subject variability in this effect is observed. Therefore, it was unclear how much of the apparent between-subject variability was due to a low signal-to-noise ratio in the measurement, vs. true between-subject differences in the magnitude of the response. The goals of this investigation were to test the within-subject reproducibility and reliability of amphetamine-induced decrease in [123I]IBZM BP with a test/retest paradigm, and to establish the presence or absence of tolerance or sensitization to single administration ofi.v. amphetamine. Six healthy male subjects, never previously exposed to psychostimulants, twice underwent measurement of striatal amphetamine-induced DA release (between-measurement interval 16 +/- 10 days) using SPECT and the [123I]IBZM constant infusion technique. Results demonstrated an excellent within-subject reproducibility of amphetamine-induced DA release: amphetamine-induced decreases in [123I]IBZM BP were significant on each day, and had an intraclass correlation coefficient (ICC) of 0.89. Moreover, values from the second experiment were not significantly different from first experiment, suggesting the absence of either sensitization or tolerance to the effect of amphetamine on DA release in these experimental conditions. The subjective activation, as rated by the subjects on analog scales, was also highly reproducible. In conclusion, this scanning technique provides a reliable measurement of amphetamine-induced reduction of [123I]IBZM BP and enables detection of between-subject differences that appear stable over time.

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Pour comparer I'impact de trois techniques d'acquiescement sur I'incitation au comportement charitable, on a demand6 A 409 personnes de verscr $2 a l ' h e r i c a n Cancer Society. Cette requtte fut immtdiatement prksentte dans trois groupes contrde et p r t d d t e dans neuf groupes expenmentau d'une demande prtliminaire correspondant A une proctdure d'aquiescement B requite multiple. On a d'abord demand6 aux sujets soumis A la technique "pied dans la porte" de ripondre 3 un questionnaire composk de 10, 35 ou 60 items. On sollicitait d'abord $10, 25 ou 50 de la part de ceux confrontis a la situation "porte dans la figure"; et $0,50, 1 ou 1.50 de la part des sujets "ras des pgquerettes". Les rtsultats montrent que les mtthodes $10 et 25 "porte dans la figure" furent les plus rentables. Les sujets contrde et "ras des piquerettes" donnhent A peu prbs la mtme chose et les conditions "pied dans la porte" furent les moins productives. On discute, A partir de ces dicouvertes, de la valeur pratique et des inconvtnients virtuels de I'application des techniques d'acquiescement requtte multiple pour stimuler le comportement charitable.To compare the relative impact of three social compliance techniques in promoting charitable behaviour 409 individuals were asked to contribute $2 to the American Cancer Society. This target request was presented alone in three control groups and preceded by an initial request framed according to a multiple-request compliance procedure in nine experimental groups. Subjects exposed to the fwt-in-the-door technique were first asked to complete either a lo-, 3 5 , or 60-item questionnaire. Those in the door-in-the-face condition were first asked to donate either $10, $25 or $50. Low-ball subjects Requests for reprints should be Sent to Richard Katzev, door-in-face procedures produced more money than any other condition. Low-ball and control subjects contributed about equivalent amounts of money, and the foot-in-the-door conditions were the least successful on each measure of charitable khaviour. These fidings were discussed in terms of both the practical value and potential disadvantages of applying multiple request social compliance techniques to promote charitable behaviour.

Monoamine oxidase A (MAO-A) inhibition was investigated both in vitro and in vivo in rat brains by using the radioligand, 18 F-fluoroclorgyline (N-[3-(2Ј,4Ј-dichlorophenoxy)-2-18 F-fluoropropyl]-N-methylpropargylamine). In vitro binding affinities of six compounds, clorgyline, Ro 41-1049, deprenyl, fluoxetine, norfluoxetine and citalopram, were studied. Fluoxetine and norfluoxetine showed in vitro affinities of 36.5 and 68 µM for MAO-A, respectively. Fluoxetine and norfluoxetine also significantly inhibited (more than 20%) the binding of the radioligand in vivo while citalopram and deprenyl showed very poor affinities in vitro for MAO-A and had no effect in vivo. The in vivo effects of the various drugs were directly comparable to their in vitro affinities for binding to MAO-A as seen in the correlation plot of percent control in vivo binding of 18 F-fluoroclorgyline and binding affinity, -log IC 50 (R 2 ϭ 0.979). An acute dose of 20 mg/kg of fluoxetine inhibited binding of 18 F-fluoroclorgyline by more than 20%, while lower doses had some significant effects. These results provide evidence on the in vitro and in vivo inhibition of monoamine oxidase A by fluoxetine.

PurposeCryothermal ablation (CTA) for atrioventricular nodal reentrant tachycardia (AVNRT) is considered safer than radiofrequency ablation (RFA) since it eliminates the risk of inadvertent AV block. However, it has not been widely adopted due to high late recurrence rate (LRR). In an effort to improve LRR, we evaluated a new approach to cryothermal mapping (CTM): “time to tachycardia termination” (TTT).MethodsThis single-center study had 88 consecutive patients who underwent CTA using TTT for AVNRT. The CTA catheter was positioned in sinus rhythm at the posteroseptal tricuspid annulus, and then AVNRT was induced. The CTA target site was identified by prompt tachycardia termination in ≤20 s during CTM. Procedural success was defined as no inducible AVNRT and ≤1 single AV nodal echoes.ResultsAcute procedural success was achieved in 87 of 88 patients (98.9 %) and was similar to prior studies for both CTA and RFA. No permanent AV block was observed. LRR was 3.7 % at a mean follow-up of 19.7 months. LRR was equivalent to that commonly reported for RFA and improved when compared to conventional CTA.ConclusionTTT for CTA of AVNRT provides enhanced safety and similar long-term efficacy when compared to RFA. Based upon this experience, TTT provides an enhancement to conventional CTA that appears to result in improved long-term outcomes. In light of these findings, it seems reasonable to undertake additional randomized trials to determine whether RFA or CTA using TTT is the optimal approach for the catheter ablation of AVNRT.

In the United States, the absorbed dose to the gallbladder would limit [C-11]-6-OH-BTA-1 administered with the approval of a Radioactive Drug Research Committee (RDRC) to a single injection of 1295 MBq (35 mCi) in the adult male, and 1314 MBq (35 mCi) in the adult female.

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