Showing papers by "Olivier F. Bertrand published in 2006"

A Randomized Study Comparing Same-Day Home Discharge and Abciximab Bolus Only to Overnight Hospitalization and Abciximab Bolus and Infusion After Transradial Coronary Stent Implantation

Abstract: Background— Systematic use of coronary stents and optimized platelet aggregation inhibition has greatly improved the short-term results of percutaneous coronary interventions. Transradial percutaneous coronary interventions have been associated with a low risk of bleeding complications. It is unknown whether moderate- and high-risk patients can be discharged safely the same day after uncomplicated transradial percutaneous coronary interventions. Methods and Results— We randomized 1005 patients after a bolus of abciximab and uncomplicated transradial percutaneous coronary stent implantation either to same-day home discharge and no infusion of abciximab (group 1, n=504) or to overnight hospitalization and a standard 12-hour infusion of abciximab (group 2, n=501). The primary composite end point of the study was the 30-day incidence of any of the following events: death, myocardial infarction, urgent revascularization, major bleeding, repeat hospitalization, access site complications, and severe thrombocytop...

Listening in Silence Activates Auditory Areas: A Functional Magnetic Resonance Imaging Study

Abstract: Directing attention to some acoustic features of a sound has been shown repeatedly to modulate the stimulus-induced neural responses. On the contrary, little is known about the neurophysiological impact of auditory attention when the auditory scene remains empty. We performed an experiment in which subjects had to detect a sound emerging from silence (the sound was detectable after different durations of silence). Two frontal activations (right dorsolateral prefrontal and inferior frontal) were found, regardless of the side where sound was searched for, consistent with the well established role of these regions in attentional control. The main result was that the superior temporal cortex showed activations contralateral to the side where sound was expected to be present. The area extended from the vicinity of Heschl's gyrus to the surrounding areas (planum temporale/anterior lateral areas). The effect consisted of both an increase in the response to a sound delivered after attention was directed to detect its emergence and a baseline shift during the silent period. Thus, in absence of any acoustic stimulus, the search for an auditory input was found to activate the auditory cortex.

Hydrophobic cluster analysis and modeling of the human Rh protein three-dimensional structures.

Abstract: Rh (Rhesus) is a major blood group system in man, which is clinically significant in transfusion medicine. Rh antigens are carried by an oligomer of two major erythroid specific polypeptides, the Rh (D and CcEe) proteins and the RhAG glycoprotein, that shared a common predicted structure with 12 transmembrane a-helices (M0 to M11). Non erythroid homologues of these proteins have been identified (RhBG and RhCG), notably in diverse organs specialized in ammonia production and excretion, such as kidney, liver and intestine. Phylogenetic studies and experimental evidence have shown that these proteins belong to the Amt/Mep/Rh protein superfamily of ammonium/methylammonium permease, but another view suggests that Rh proteins might function as CO2 gas channels. Until recently no information on the structure of these proteins were available. However, in the last two years, new insight has been gained into the structural features of Rh proteins (through the determination of the crystal structures of bacterial AmtB and archeaebacterial Amt-1. Here, models of the subunit and oligomeric architecture of human Rh proteins are proposed, based on a refined alignment with and crystal structure of the bacterial ammonia transporter AmtB, a member of the Amt/Mep/Rh superfamily. This alignment was performed considering invariant structural features, which were revealed through Hydrophobic Cluster Analysis, and led to propose alternative predictions for the less conserved regions, particularly in the N-terminal sequences. The Rh models, on which an additional Rh-specific, N-terminal helix M0 was tentatively positioned, were further assessed through the consideration of biochemical and immunochemical data, as well as of stereochemical and topological constraints. These models highlighted some Rh specific features that have not yet been reported. Among these, are the prediction of some critical residues, which may play a role in the channel function, but also in the stability of the subunit structure and oligomeric assembly. These results provide a basis to further understand the structure/function relationships of Rh proteins, and the alterations occurring in variant phenotypes.

Experiencing and detecting happiness in humans: the role of the supplementary motor area.

Abstract: Understanding emotions in others may involve neural structures implicated in both perception and action.1 Laughter is a socially important behavior and its neural correlates are poorly understood. Depth electrode electrophysiological techniques offer a rare opportunity to both record and stimulate neural structures involved in emotion processing. (2,3) This kind of direct electrophysiological investigation in humans is particularly determinant because laughter processing cannot be studied in animals.

Usefulness of Fractional Flow Reserve Measurements to Defer Revascularization in Patients With Stable or Unstable Angina Pectoris, Non–ST-Elevation and ST-Elevation Acute Myocardial Infarction, or Atypical Chest Pain

Abstract: This study determined the safety of deferring coronary revascularization based on a fractional flow reserve (FFR) value ≥0.75 in a series of consecutive unselected coronary patients with moderate coronary lesions, including patients with unstable angina, myocardial infarction (MI), and/or positive noninvasive test findings. The study included 201 consecutive coronary patients (mean age 62 ± 10 years; 65% men) with 231 lesions evaluated by FFR measurement for which revascularization was deferred based on a FFR value ≥0.75. Lesions associated with a positive noninvasive test result were those located in an artery supplying a myocardial territory in which myocardial ischemia was demonstrated by a noninvasive test. Cardiac events (cardiac death, MI, revascularization) and Canadian Cardiovascular Society angina class were evaluated at follow-up. Indications for coronary angiography included unstable angina or MI (62%), stable angina (30%), or atypical chest pain (8%). Forty-four patients (22%) had ≥1 coronary lesion associated with a positive noninvasive test result in which FFR was evaluated. Mean FFR value was 0.87 ± 0.06 and mean lesion percent diameter stenosis was 41 ± 8%. At 11 ± 6 months of follow-up, cardiac events occurred in 20 patients (10%), and no significant differences were observed between patients with unstable angina or MI and those with stable angina (9% vs 13%, p = 0.44) or between patients with and without lesions associated with positive noninvasive test results (9% vs 10%, p = 1.00). At the end of follow-up, 88% of patients were asymptomatic in angina class 0 or I, with no differences across various groups. In conclusion, these results suggest that patients with moderate coronary lesions can be safely managed without revascularization on the basis of FFR measurements, irrespective of clinical presentation and/or presence of positive noninvasive test results.

Functional Significance of Olfactory-induced Oscillations in the Human Amygdala

Abstract: We recorded directly from the amygdalar nucleus of nine epileptic patients performing a delayed odor-matching recognition memory task. Time-frequency analysis of the responses to the odorants revealed that the stimulations elicited induced oscillatory responses, as well as already described olfactory evoked potentials. These oscillatory responses were composed of two frequency components--one in the beta band (15-25 Hz) and a faster one, in the low gamma band (25-35 Hz)--both of which lasted during the full duration of the inspiration. In pairs of identical odorants, the power of gamma oscillations was weaker for the second odorant (the target) than for the first one (the sample). We observed no such difference when the first and second odorants of a pair were different. Thus, gamma oscillations in the amygdala are weaker for repeated stimuli, a mechanism known as repetition suppression. This is consistent with an involvement of the human amygdala in the encoding and retrieval of olfactory information independently of its hedonic properties, at least in epileptic patients. Altogether, our results corroborate in humans evidence found in animals that oscillations serve as a common coding process of olfactory information.

Gamma Oscillations in Humans

Abstract: Gamma oscillations in human electroencephalographic signals are defined by their frequency range, from 20 Hz up to 100 Hz. Different types of oscillations are related to arousal states, early sensory processes, and neural mechanisms of sensory or cognitive binding by oscillatory synchronization. Keywords: binding; synchronization; EEG; MEG; temporal code