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Biomedical subjects

J Leblond

Publications and source records attributed to J Leblond.

15 recordsLinked to original sources
PubMed2003

Group therapy for pathological gamblers: a cognitive approach.

This study evaluated the efficacy of a group cognitive treatment for pathological gambling. Gamblers, meeting DSM-IV criteria for pathological gambling, were randomly assigned to treatment (N=34) or wait-list control (N=24) conditions. Cognitive correction techniques were used first to target gamblers' erroneous perceptions about randomness, and then to address issues of relapse prevention. The dependent measures used were the DSM-IV criteria for pathological gambling, perceived self-efficacy, gamblers' perception of control, desire to gamble, and frequency of gambling. Post-treatment results indicated that 88% of the treated gamblers no longer met the DSM-IV criteria for pathological gambling compared to only 20% in the control group. Similar changes were observed on all outcome measures. Analysis of data from 6-, 12- and 24-month follow-ups revealed maintenance of therapeutic gains. Recommendations for group interventions are discussed, focusing on the cognitive correction of erroneous perceptions toward the notion of randomness.

Adult↗
PubMed2002

PFG NMR measurements of flow through porous media: effects of spatial correlations of the magnetic field and the velocity field.

Used for a long time for diffusion studies, PFG NMR techniques are now widely used to study flow through porous media. We discuss here the effects of the magnetic field inhomogeneities and the finite gradient pulse duration in this case. We propose a statistical model based on spatial correlations of the magnetic field and velocity field and as far as we can, we draw practical conclusions on the PFG NMR measurements conditions.

Journal Article↗
PubMed2001

Cognitive treatment of pathological gambling.

This study evaluated the efficacy of a cognitive treatment package for pathological gambling. Sixty-six gamblers, meeting DSM-IV criteria for pathological gambling, were randomly assigned to treatment or wait-list control conditions. Cognitive correction techniques were used first to target gamblers' erroneous perceptions about randomness and then to address issues of relapse prevention. The dependent measures used were the South Oaks Gambling Screen, the number of DSM-IV criteria for pathological gambling met by participants, as well as gamblers' perception of control, frequency of gambling, perceived self-efficacy, and desire to gamble. Posttest results indicated highly significant changes in the treatment group on all outcome measures, and analysis of data from 6- and 12-month follow-ups revealed maintenance of therapeutic gains. Recommendations for clinical interventions are discussed, focusing on the cognitive correction of erroneous perceptions toward the notion of randomness.

Adult↗
PubMed2000

Is the SOGS an accurate measure of pathological gambling among children, adolescents and adults?

The South Oaks Gambling Screen (SOGS) is widely used to assess the prevalence of pathological gambling. For a variety of reasons, this instrument may not provide an accurate rate of the prevalence of pathological gambling. In this paper, one source of error in data provided by the SOGS is investigated. It is argued that individuals may not fully understand the meaning of some items, and that clarification of the meaning of misunderstood items may in some cases lead to a changed score on the scale. The present study evaluates respondents' understanding of the SOGS items. The results from three studies are reported, each using a different sample: grade school children, adolescents and adults. It was hypothesised that (1) participants would not understand some items of the SOGS, (2) problem gamblers and probable pathological gamblers would be more inclined to interpret items incorrectly than would non-problem gamblers and, (3) consistent with the first two hypotheses, clarification of items would decrease the number of participants identified as problem gamblers or probable pathological gamblers. The data obtained supported hypotheses 1 and 3. Furthermore, hypothesis 2 was supported for grade school children, but not for adolescents or adults. These results are consistent with recent literature on endorsement and acquiescence phenomena, and have implications for prevalence studies of probable pathological gambling.

Journal Article↗
PubMed2000

Analysis of a casino's self-exclusion program.

As gambling facilities become more available, the number of pathological gamblers increases. Effective therapeutic and preventive interventions should be developed and systematically evaluated. Self-exclusion programs may be a useful means to facilitate self-control among problem gamblers. This paper describes the characteristics of individuals who decided to bar themselves from a Canadian casino. Two hundred twenty individuals participated in the present study and completed a questionnaire including four sections: (1) socio-demographic data, (2) the South Oaks Gambling Screen, (3) gambling habits, and (4) prior experiences with the self-exclusion program. According to the SOGS, 95% of the participants were classified as severe pathological gamblers on the SOGS (Mean score = 9.87). Furthermore, based on self-reported observation, 30% of the participants completely stopped gambling once enrolled in this program. No one scored within the interval of non-problem gamblers. Suggestions to improve self-exclusion programs are discussed.

Journal Article↗
PubMed1998

A Pulsed Field Gradient NMR Technique for the Determination of the Structure of Suspensions of Non-Brownian Particles with Application to Packings of Spheres.

The internal structure of systems of particles in a liquid is studied with a novel NMR technique based on the measurement of the squared modulus of the magnetization in presence of a pulsed field gradient. The formalism is analogous to the one used in classical scattering techniques (light, X-rays, neutrons); it allows similar information to be obtained about the structure (in particular, the structure factor S(q)). The main improvement is that the range of particles sizes is 10 µm to 1 mm, as compared with the range of the scattering techniques (<5 µm). The NMR technique was validated by studying packings of spherical particles of mean diameter 240 µm created by sedimentation. The profile of the experimental squared modulus of the magnetization versus the wave vector provides results for the mean size of particles and the compacity. The main feature is that it depends on the pair distribution function, and the present results are in good agreement with a model based on the Percus-Yevick approximation. This technique is then particularly adapted to systems such as non-Brownian suspensions, fluidized beds, porous media, and sediments. Copyright 1998 Academic Press.

Journal Article↗
PubMed1996

Pulsed field gradient NMR measurements of probability distribution of displacement under flow in sphere packings.

In this work we used the PFG NMR displacement technique to investigate the transport of water particles under flow through a model porous media. Using different sizes of sphere for monodisperse glass sphere packings, we measured the probability distribution of displacement for mean displacements ranging from 0.08 to 7.3 times the characteristic length of the porous media. We observed, therefore, the transition between the velocity probability distribution and the Gaussian-shaped distribution of classical dispersion.

Glass↗
PubMed1992

[Reconstruction of the external ear].

The authors after a short morphological description of the microtia, expose the surgical evolution which had led to the actual auricular reconstruction technique, using a costal cartilage framework. This technique requiring several steps is exposed in the typical case of microtia. It is the preferential method. The difficult reconstructions due to the poor quality of the skin are exposed by degree of complexity: in these cases, tissue expansion, fascia temporalis superficialis can be useful and finally auricular prostheses, attached to bone-integrated implants, can be recommended. The functional surgery of the middle ear is also replaced in the context of the auricular reconstruction which is done around 8 years old.

Burns↗
PubMed1991

Temperature dependence of extracellular ionic changes evoked by anoxia in hippocampal slices.

1. Extracellular [K] and [Ca] were measured with ion-selective microelectrodes in CA1 pyramidal cell layer of rat hippocampal slices in an interface chamber. 2. Near room temperature (21-22 degrees C), brief periods of anoxia (3- to 4-min substitution of 95% N2-5% CO2 for 95% O2-5% CO2) produced very small changes in [K]o [-0.022 +/- 0.10 (SE) mM] or [Ca]o (-0.030 +/- 0.0029 mM) and were associated with only minor depression of population spikes (-22.5 +/- 11%). 3. Stratum radiatum (SR) stimulation (0.2-5 Hz) could evoke substantial increases in [K]o (by 0.2-2 mM); although variable, they were consistent in any one slice. The same stimulation regularly caused only small depressions of [Ca]o (by less than 0.1 mM, typically). 4. Also at 21-22 degrees neither stimulation nor anoxia generated more than minimal reductions in extracellular space [by 2.3 +/- 0.94%, as measured by the tetramethylammonium (TMA) method], and spreading depression (SD) occurred in only 1 out of 20 slices. 5. At 33-34 degrees C, anoxia (also for 3-4 min) consistently produced more substantial increases in [K]o (0.83 +/- 0.18 mM); but the apparent changes in [Ca]o at 33 degrees C (0.058 +/- 0.12 mM) could not with certainty be distinguished from thermoelectric artifacts. There was a severe depression of population spikes (-76 +/- 10%). 6. Although electrical stimulation evoked greater reductions in [Ca]o, increases in [K]o were 50% smaller. 7. During anoxia at 33-34 degrees C, the extracellular space was significantly reduced, by 6.1 +/- 0.9%. Moreover, in 37% of the slices, either stimulation or anoxia triggered massive increases in [K]o (greater than 10 mM) and large reductions in [Ca]o (less than 1 mM), associated with SD-like swings in focal potential. 8. It is concluded that the extracellular ionic changes evoked by brief anoxia do not contribute in a major way to the depression of synaptic transmission.

Action Potentials↗
PubMed1989

Mediation of acetylcholine's excitatory actions in central neurons.

In experiments on the hippocampus in situ (in rats under urethane), neither cyclic GMP nor H-8 (an antagonist of cyclic nucleotide-dependent kinases) had much effect on CA1/CA3 population spikes or on the excitatory action of ACh. This is further evidence against the idea that cyclic nucleotides play a major role as cholinergic second messengers. On the other hand, the results of tests with a PKC antagonist sphinganine are in keeping with some involvement of PKC in cholinergic actions. (Another PKC antagonist, H-7, proved to be a very powerful excitant, probably via disinhibition). Preliminary experiments on CA1 neurons in hippocampal slices (by single electrode voltage clamp), confirmed previous reports that carbachol depresses A- and C-type K currents, as well as inward Ca2+ currents; though the latter effect was sometimes mainly due to frequency-dependent inactivation of Ca currents. It is suggested that a single, primary muscarinic action, the acceleration of phosphinositide turnover, may account for a variety of secondary effects: on the one hand, via activation of PKC, a number of possible PKC-mediated actions, such as block of the slow AHP; on the other, via IP3 formation, a block of IM and a rise in cycloplasmic free Ca2+ that may cause inactivation of both Ca2(+)-inward currents, and Ca2(+)-dependent GKs.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1989

Hypoxic changes in hippocampal neurons.

1. Reversible effects of brief periods of anoxia (replacing 95% O2-5% CO2 with 95% N2-5% CO2 for 2-4 min) were studied in CA1 neurons in hippocampal slices (from Sprague-Dawley rats), kept in an interface-type chamber at 33.5 degree. 2. The predominant voltage change during anoxia (N2) was a hyperpolarization, accompanied by a marked fall in resistance and excitability; synaptic potentials were also depressed, especially inhibitory postsynaptic potentials (IPSPs). 3. In voltage-current (V-I) plots, the N2-evoked hypolarization had a reversal potential below -90mV, even when recording with 2 M KCl electrodes and after substituting 90% of medium Cl- with isethionate. The accompanying fall in input resistance (RN) is therefore probably caused by an increase in K conductance (in agreement with previous reports). There was evidence that anomalous rectification enhances the fall in RN but limits the hyperpolarization. 4. These effects of anoxia were not fully blocked by any of the K-channel antagonists tested, including Cs, TEA, 4-AP, quinine and apamin. 5. Intracellular injections of Ca chelators caused a variable depression of N2-evoked reductions in RN. 6. It is unlikely that N2 activates ATP-sensitive K channels as tolbutamide enhanced rather than depressed the hyperpolarization and fall in RN. 7. When early depletion of cellular ATP was prevented by incubation in creatine (25 mM for greater than 1 h), even longer anoxic periods produced only minor changes in potential, RN, and synaptic transmission. 8. It was concluded that activation of K conductance by a rise in cytosolic-free Ca2+ is the most plausible of several possible underlying mechanisms.

4-Aminopyridine↗
PubMed1989

Changes in membrane currents of hippocampal neurons evoked by brief anoxia.

1. Effects of anoxia (2-4 min of 95% N2-5% CO2) on membrane currents of CA1 neurons were studied by single-electrode voltage clamp in hippocampal slices (from Sprague-Dawley rats) kept in an interface-type chamber at 33.5 degree. 2. When recording with KCl electrodes at a holding potential (VH) near-70 mV, anoxia evoked a slow outward current [0.18 +/- 0.06 (SE) nA], accompanied by a conductance increase ( + 46 +/- 20%, mean +/- SE). The difference current evoked by N2 had a reversal potential near-100 mV. It was much smaller in presence of 2-4 mM extracellular Cs, and any remaining outward current was abolished by 10 mM tetraethylammonium (TEA). Only inward currents were observed when recording with CsCl electrodes. 3. Inward relaxations evoked by large hyperpolarizing pulses from VH less than or equal to - 70 mV (Q-type) were not significantly depressed by anoxia (-1.5 +/- 6.0%). 4. Some voltage-dependent outward currents (evoked by 200-ms depolarizing pulses) were depressed during anoxia: 1) a fast-inactivating (A-like) current, obtained at VH less than or equal to -70 mV and suppressed by 200 microM 4-AP, was reduced by 25.6 +/- 7.3% (n = 5); 2) a slower, noninactivating (C-like) current, suppressed by TEA, was reduced by 52 +/- 7.2% (n = 16). Neither of these currents (1 or 2) was observed when recording with 2- to 3-M CsCl electrodes; and 3) small (M-like) inward relaxations, observed at VH approximately -40 mV 5. Net inward currents could be evoked after blockage of GK with 10 mM TEA when recording with KCl electrodes or by recording with CsCl electrodes. At VH less than or equal to -70 mV, large, transient, and incompletely controlled currents were evoked by depolarizing pulses; at VH less than or equal to -50 mV, smaller and more persistent currents were evoked by depolarizing pulses (L-like), and transient currents (T-like?) were seen immediately after hyperpolarizing pulses. 6.L-type currents (at VH less than or equal to -50 mV) were nearly abolished after 1-2 min anoxia (by approximately 90%). This was equally true of the currents evoked by constant pulses or peak currents in I-V plots. After reoxygenation, recovery was biphasic, with a quick early phase (to 50-80% in 2 min) and then a much slower one (to 60-90% by 10-15 min).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Anoxia reversibly suppresses neuronal calcium currents in rat hippocampal slices.

Intracellular recording from CA1 neurons confirmed that short periods of anoxia (95% N2 + 5% CO2 for 2-4 min) have a hyperpolarizing action, caused by a rise in K conductance. After blockage of K channels with extracellular Cs+ and tetraethylammonium (or intracellular Cs+), large inward currents of Ca were evoked by depolarizing pulses: transient currents at a holding potential near -70 mV, and more sustained ones near -50 mV. Both types of Ca current were much reduced or fully suppressed after 1-3 min of anoxia, but they largely (or fully) recovered within 1-10 min of starting reoxygenation.

Animals↗