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Biomedical subjects

J P Laurent

Publications and source records attributed to J P Laurent.

At least 19 recordsLinked to original sources
PubMed2003

Functional analysis of the deficit in semantic context processes in schizophrenic patients: an event-related potentials study.

AIM: Schizophrenic patients exhibit a deficit in the semantic context processing strategies which might be responsible for the language and communication disorders that are characteristic of this condition. The aim of our study was to identify the nature of the contextualization processes which are lacking in schizophrenic patients, by distinguishing between processes for the generation of expectations and processes of semantic integration. PATIENTS AND METHOD: Thirteen schizophrenic patients and 12 healthy controls performed two tasks: (a) a lexical decision task (LDT) with a highly structured sentence context and whose experimental characteristics made it possible to call strongly on predictive strategies, and (b) a LDT with classic semantic priming (the context being reduced to a single word). In this latter task, the small number of related words did not prompt the generation of expectations but instead called on the postlexical integration process. The event-related potentials (ERP) were recorded during the administration of the task. RESULTS AND CONCLUSION: In the sentence task, we observed a modulation in the N400 amplitude due to the presence of expectations both in the schizophrenic and control participants: predictable words evoked a small N400 amplitude compared to the non-predictable words. In contrast, in the simple (priming) task, the semantic link evoked an N400 amplitude modulation in the control group exclusively. Our results indicate that schizophrenics could be able to use context to activate expectations for the most highly predictable item, and that their deficit appears when the processing strategy is based on the integration of the context stored in working memory.

Adult↗
PubMed2001

Long-term (> or =8 years) outcome after Palmaz-Schatz stent implantation.

The purpose of this single-center study was to evaluate the long-term (> or =8 years) outcome of Palmaz-Schatz intracoronary stenting and to identify independent predictors of outcome. Although short-term results of Palmaz-Schatz intracoronary stenting have been promising, with a reduction in both angiographic restenosis and clinical cardiac events up to 3 years, longer-term follow-up has not been established. We analyzed clinical outcome in 426 consecutive patients at least 8 years after coronary stenting. Demographic, clinical, and procedural predictors of restenosis, survival, and event-free survival, defined as freedom from death, myocardial infarction (MI), and coronary revascularization (target stented site, target vessel, and any revascularization) were analyzed. Before discharge, 28 patients (6.6%) sustained at least 1 major cardiovascular event: 3 deaths (0.7%), 18 MIs (4.2%), and 17 repeat revascularizations. Surviving patients were followed for 8.9 years (interquartile range 8.4 to 9.4). After discharge, 59 patients (13.9%) died, 47 (11.1%) sustained an MI, and 188 (44.4%) underwent coronary revascularization. The 8-year event-free survival (freedom from death, freedom from death/MI/target-stented site revascularization, and freedom from death/MI/any coronary revascularization) was (mean +/- SE) 0.86 +/- 0.01, 0.62 +/- 0.03, and 0.47 +/- 0.02, respectively. Unstable angina, lower left ventricular ejection fraction, and saphenous vein graft stenting were found to be independent predictors of death during follow-up. Hypertension, unstable angina, multivessel disease, and multiple stent implantation were found to be independent predictors of the composite of death/MI/any coronary revascularization during follow-up. This study provided a useful assessment of very long-term outcome in survival, event-free survival, and predictors of major cardiac events 8 to 10 years after Palmaz-Schatz stent implantation.

Coronary Angiography↗
PubMed2001

Antineuronal nuclei immunohistochemical staining patterns in childhood ependymomas.

NeuN, the mouse-derived monoclonal antibody to the reportedly neuron-specific nuclear protein, has been observed to react with many different types of normal, postmitotic neurons throughout the central and peripheral nervous systems. We retrospectively examined 23 surgical specimens (collected from 20 patients) originally diagnosed at our institution between 1983 and 1999 as ependymoma (9), myxopapillary ependymoma (1), anaplastic/malignant ependymoma (10), and primitive neuroectodermal tumor with ependymal differentiation (3). The ependymomas included lesions from the spine (3), cerebrum (5), and posterior fossa (15). Representative formalin-fixed, paraffin-embedded sections from each tumor were subjected to immunohistochemical staining with antibody against NeuN (Chemicon International, Inc, Temecula, CA). Five astrocytomas, four primitive neuroectodermal tumors, and normal cerebral cortex and ependyma from autopsy brains of premature newborns, term infants, and older children served as controls. Thirteen ependymal tumors had positive nuclear staining ranging from rare tumor cells to numerous groups of cells; of these, 9 were anaplastic ependymomas and had the most staining. These studies suggest that some ependymomas arise from a pluripotential neuroglial cell.

Antibodies, Monoclonal↗
PubMed2000

Morphological and immunocytochemical characterization of electrophysiologically investigated neurons in the PVN of the rat.

This study was carried out to characterize angiotensin II (ANG II) sensitive neurons in the hypothalamic paraventricular nucleus (PVN) of the rat. An approach was chosen in which a combination of an electrophysiological, a morphological, and an immunocytochemical method was focused on one single neuron. The cell's reaction to an application of ANG II and its specific antagonist Losartan (Dup753) was investigated using the technique of intracellular recording inside 450-microm-thick brain slices. A final injection of a fluorescent dye labelled the neurons. Optical sections were taken through the marked cells by a confocal laser-scanning microscope and made into a three-dimensional cell model on a computer. One-micrometer thin sections were cut from the thick slice at the level of the electrophysiologically characterized and marked cell body for immunocytochemical tests with different antibodies. Our results show an example of such a neuron inside the PVN excited by ANG II. It was possible to block this excitation with the specific ANG II receptor subtype 1 (AT1) antagonist Losartan. The result indicated that the ANG II reaction was mediated by the AT1 receptor subtype. Immunocytochemical studies show that this ANG II-sensitive neuron contains ANG II but no vasopressin. The combination of the results enables us to gain improved information on interactions of peptidergic systems.

Angiotensin II↗
PubMed2000

Is ferromagnetism an intrinsic property of the CuII/GdIII couple? 1. Structures and magnetic properties of two novel dinuclear complexes with a mu-phenolato-mu-oximato (Cu,Gd) core.

Two original dinuclear (Cu(II),Gd(III)) complexes (1 and 2) deriving from polydentate nonsymmetrical Schiff base ligands LiH2 have been prepared. Formally they differ by the length of the diamino chain. They crystallize in the orthorhombic Pbca (No. 61) (1) and in the monoclinic P2(1/n) (No. 14) (2) space groups. The cell parameters are a = 12.6295(7) A, b = 20.7894(9) A, c = 18.3301(13) A, and Z = 8 for 1 and a = 12.7246(16) A, b = 13.5691(17) A, c = 14.5310(19) A, beta = 94.629(16) degrees , and Z = 4 for 2. These structural studies show that in both complexes the CuII and GdIII ions are doubly bridged by a phenolato oxygen atom and an oximato (N-O) pair. The bridging network is not planar. The more important distortions are observed for the complex having the larger diamino chain. Unexpectedly the latter complex presents an antiferromagnetic interaction, but the related J value is small (J approximately equal to -0.49 cm(-1)). In the former complex the interaction is ferromagnetic (J approximately equal to 3.5 cm(-1)) as it is for complexes containing (CuO2Gd) bridging cores which yield J values varying from 1.4 to 10.1 cm(-1).

Journal Article↗
PubMed2000

In-stent restenosis: long-term outcome and predictors of subsequent target lesion revascularization after repeat balloon angioplasty.

OBJECTIVES: We sought to evaluate the long-term clinical outcome of patients undergoing successful balloon angioplasty for in-stent restenosis, and to determine correlates of the need for subsequent target lesion revascularization (TLR). BACKGROUND: In-stent restenosis can be safely treated by repeat percutaneous intervention. Reported subsequent TLR rates have varied from 20% to 80% and seem related to the type of restenotic lesion. METHODS: The study population comprised 234 patients with follow-up data who were successfully treated with repeat balloon angioplasty for in-stent restenosis in 257 lesions between May 1995 and January 1998 at our institution. RESULTS: Clinical follow-up was available at 459 (286 to 693) days after the repeat procedure. Event-free survival was 78.5% and 74.6% at 12 and 24 months, respectively. Recurrent events occurred in 58 patients (24.8%), including 6 deaths (2.6%), 4 myocardial infarction (1.7%) and repeat target vessel revascularization in 50 patients (21.4%). Independent predictors of repeat TLR were time to in-stent restenosis <90 days (Hazard ratio 4.67, p < 0.001), minimal luminal diameter after repeat procedure (Hazard ratio 0.38, p = 0.034) and the angiographic pattern of in-stent restenosis (Hazard ratio 1.65, p = 0.036). CONCLUSIONS: Balloon angioplasty is an effective means of treating in-stent restenosis. The long-term results are acceptable particularly for focal restenotic lesions. Further restenosis is more common in patients with early initial recurrence, more proliferative lesions and a poorer angiographic result from repeat angioplasty.

Aged↗
PubMed2000

Auditory attention processing in 5-year-old children born preterm: evidence from event-related potentials.

The assumption that children born preterm have difficulties in maintaining active attention was tested in passive and active tasks. Twenty 5-year-old children born preterm at 26 to 32 weeks gestational age were compared with 20 children born at term, matched for age and IQ, using an auditory paradigm. In the passive task participants had to watch a videotape of a cartoon and ignore auditory stimuli. In the active task they had to detect a rare tone (the 'target' tone; 10% of the tones presented) among frequent tones (the 'standard' tone; 90%). Accuracy and reaction time were analysed, and event-related potentials (ERPs) were recorded at the scalp sites Fz, Cz, T3, T4, Pz, Oz, and two electrodes for the left mastoid (passive task); and Fz, F7, F8, Cz, T3, T4, Pz, and Oz (for the active task). Behavioural and electrophysiological data were analysed with repeated-measure ANOVAs. The results showed a significant group effect only on the active task. The preterm group scored fewer correct hits (correct detection of target tone) and were less efficient in their attentional strategy as assessed by ERP components.

Attention↗
PubMed2000

[Percutaneous coronary angioplasty via the radial artery. Feasibility and safety].

The authors report the results of percutaneous coronary angioplasty using the radial approach with respect to feasibility and safety. Between February 1994 and December 1998, out of a total of 9,070 coronary angioplasties performed in our Institute, the radial arterial approach was chosen in 5,354 cases (59%). During this period, the proportion of procedures performed via the radial artery progressively increased to 78% of cases in 1998. Cannulation of the radial artery was successful in 5,244 cases (98%). Rotatory atherectomy was used in 96 cases (2%), the excimer laser in 38 cases (1%) and stenting was performed in 3,350 cases (64%). Angiographic success was obtained in 5,224 patients (99%). Serious cardiac complications occurred in 82 patients (1.5%), including 17 deaths (0.3%), 22 Q wave myocardial infarctions (0.4%), 28 non-Q wave infarcts (0.5%), 5 coronary bypass procedures (0.1%) and 10 sub-acute occlusions (0.2%). The vascular complications included 1 death due to an ischaemic cerebrovascular accident, 25 haematomas at the puncture site (0.5%) and 3 surgical arterial repairs. The radial pulse disappeared after the procedure in 4% of cases, all asymptomatic. Angioplasty by the radial artery in the hands of trained operators is feasible and associated with a relatively low rate of cardiac and vascular complications.

Aged↗
PubMed1999

Coronary stenting in diabetics: immediate and mid-term clinical outcome.

Balloon angioplasty in diabetics is associated with acceptable immediate results but with high rates of restenosis, target vessel revascularization, and late mortality. The impact of coronary stenting on the outcome of these patients remains controversial. We reported the immediate and mid-term clinical outcome of 272 consecutive diabetic patients, representing 12.5% of the population undergoing coronary stenting between May 1995 and April 1997. Diabetes mellitus was insulin-requiring in 58 patients and non-insulin-requiring in 214. Stenting performed on large vessels (mean diameter >/=3 mm) was successful in 99.2% of nondiabetic patients and in all cases in diabetics. During in-hospital stay, the complications rate, including mortality, nonfatal myocardial infarction, emergency coronary bypass surgery, and stent subacute thrombosis, was similar in nondiabetic patients, insulin-requiring, and non-insulin-requiring diabetics (2.55%, 0%, and 2.0%, respectively). No complication occurred in the insulin-requiring group. One patient (0.5%) died from myocardial infarction and another (0.5%) presented a nonfatal myocardial infarction (subacute stent thrombosis) in the non-insulin-requiring group. The clinical follow-up (mean length 13 +/- 8 months) was obtained in 93% and 97% of the insulin-requiring and non-insulin-requiring diabetics, respectively. Overall mortality was significantly higher in insulin-requiring patients (9.3% vs. 2.4%). Nonfatal myocardial infarction and target lesion revascularization rates were similar in the two groups (0% vs. 0.5% and 8.2% vs. 10.5%). These results suggest that coronary stenting in diabetics could be performed with acceptable immediate and mid-term results. Cathet. Cardiovasc. Intervent. 47:279-284, 1999.

Aged↗
PubMed1999

Fluency versus conscious recollection in category-production performance: the performance of schizophrenic patients.

The purpose of this study was to investigate the relative contribution in schizophrenics of automatic processes (fluency) and conscious processes (conscious recollection) for the control of preencoded material in category production tasks. In one condition (Exclusion condition), subjects were told specifically not to produce previously presented words during the category-production task. This condition was compared with a standard category-production task in which subjects were told to produce the six first words that came to mind for a semantic category (Inclusion condition). In the inclusion condition, the effects of conscious control and automatic processes operated in the same direction, whereas in the exclusion condition automatic influences and conscious control were opposed. A recognition task followed the category-production tasks. Since the exclusion condition required conscious control of encoded items, we hypothesized that schizophrenic patients would be less able than control subjects to avoid producing study list items. These results indicated that schizophrenics' performance differed from these of control subjects in the exclusion condition but not in inclusion condition. Recognition performance was similar in both the schizophrenic and the control groups. These results suggest a defective conscious control in schizophrenic patients and confirm the data from the literature on explicit memory in these patients.

Female↗
PubMed1999

Variation of transient gene expression within single lineages of Trypanosoma cruzi.

The biodiversity of Trypanosoma cruzi is one of the main factors complicating the understanding of its molecular epidemiology. As an alternative to classical genetic methods, investigators have used DNA-mediated transformation techniques to study this diversity. Recently, transient expression data were shown to correlate with the genetic data. This led investigators to speculate on a potential speciation within clonal populations of Trypanosoma cruzi. To further test the phylogenetic significance of transient expression analysis in Trypanosoma cruzi, multiple plasmids were used to drive the expression of a reporter gene in different parasite populations. In our study, population specific expression of the reporter gene was observed but the variability revealed by these transient expression assays was very large and did not follow the grouping of Trypanosoma cruzi populations in 2 lineages. In this report, we discuss some of the limitations of transient assays on such a diverse parasite.

Animals↗
PubMed1999

Decreased GABAA-receptor clustering results in enhanced anxiety and a bias for threat cues.

Patients with panic disorders show a deficit of GABAA receptors in the hippocampus, parahippocampus and orbitofrontal cortex. Synaptic clustering of GABAA receptors in mice heterozygous for the gamma2 subunit was reduced, mainly in hippocampus and cerebral cortex. The gamma2 +/- mice showed enhanced behavioral inhibition toward natural aversive stimuli and heightened responsiveness in trace fear conditioning and ambiguous cue discrimination learning. Implicit and spatial memory as well as long-term potentiation in hippocampus were unchanged. Thus gamma2 +/- mice represent a model of anxiety characterized by harm avoidance behavior and an explicit memory bias for threat cues, resulting in heightened sensitivity to negative associations. This model implicates GABAA-receptor dysfunction in patients as a causal predisposition to anxiety disorders.

Animals↗
PubMed1998

Hybridization mapping of Trypanosoma cruzi chromosomes III and IV.

As part of the Trypanosoma Genome Initiative launched by the World Health Organization (WHO), a physical clone map of Trypanosoma cruzi chromosomes III and IV was generated to facilitate both DNA sequence analysis of the parasite's genome and the investigation of chromosome organization. Apart from a few genetic markers, anonymous cosmids were taken from chromosomal sublibraries and individually hybridized to filter arrays of the relevant cosmid library. The probe order was determined from the hybridization fingerprint results and used to define a fitting clone order, with few gaps remaining. The results were independently verified by hybridizations to a bacterial artificial chromosome (BAC) library and, in case of chromosome III, restriction mapping. For gap closure, additional experiments on a total cosmid library were carried out. The possible tiling paths consist of 26 clones for chromosome III (610 kbp) and 28 clones for chromosome IV (680 kbp).

Animals↗
PubMed1998

Trypanosoma cruzi: impact of clonal evolution of the parasite on its biological and medical properties.

Trypanosoma cruzi populations are subdivided into natural clones that can exhibit considerable genetic differences. It has been proposed that T. cruzi clonal structure has a major impact on this parasite's biological properties. The present work aims at testing this hypothesis. Twenty-one stocks isolated from various ecological cycles, places, and hosts were characterized by multilocus enzyme electrophoresis (MLEE) with 22 genetic loci and random amplification of polymorphic DNA (RAPD) with 10 primers on the one hand and by 14 different biological parameters on the other hand. These parameters were related to: (i) growth kinetics of epimastigotes and amastigotes; (ii) infection of culture cells by amastigotes; (iii) viability of extracellular trypomastigotes; or (iv) sensitivity of epimastigotes, trypomastigotes, and amastigotes to Benznidazole and Nifurtimox. MLEE and RAPD results exhibited parity to each other, as previously noted (M. Tibayrenc, K. Neubauer, C. Barnabé, F. Guerrini, D. Skarecky, and F. J. Ayala, 1993, Proceedings of the National Academy of Sciences of the USA 90, 1335-1339), and showed that the 21 stocks were distributed into three main genetic groups, 19/20, 32, and 39, corresponding to the major clones 19, 20, 32, and 39 previously described on the basis of 15 isozyme loci. Most biological parameters showed a strong correlation to the genetic distances evaluated from either MLEE or RAPD, which favors the working hypothesis. The only exception came from drug sensitivity estimated on trypomastigote forms. The overall results made it possible to firmly reject the null hypothesis that there is no relationships between evolutionary distances and biological differences in T. cruzi natural clones.

Animals↗
PubMed1998

[Implantation of coronary stents in diabetic patients. Short- and medium-term clinical results].

Coronary balloon angioplasty is associated with a high incidence of restenosis in diabetics and of revascularisation of the culprit lesion and increased long-term mortality. The authors report the short and medium-term results of coronary stenting in diabetics. Between May 1995 and April 1997, 2,182 patients underwent coronary stenting. This population included 272 diabetics : 58 insulin-dependent and 214 non-insulin dependent (oral antidiabetics). Stents were implanted in vessels with mean diameters of 3 mm and over. During the hospital period, the complication rate (mortality, non-fatal myocardial infarction, emergency coronary bypass surgery, subacute thrombosis of the stent) was comparable in non-diabetics, insulin-dependent and non-insulin-dependent diabetics (2.55, 0 and 2.0% respectively). One patient (0.5%) died and another (0.5%) had non-fatal myocardial infarction (thrombosis of the stent) in the non-insulin-dependent group. No complications were observed in the insulin-dependent diabetic group. The mean clinical follow-up of 13 months (3-26 months) was respected in 93 and 97% of diabetics. The non-fatal myocardial infarction rate and revascularisation of the culprit lesion were comparable in the insulin and non-insulin-dependent groups (0 versus 0.5% and 8.2 versus 10.5% respectively) but global mortality was higher in the insulin-dependent diabetics (9.3 versus 2.4%).

Aged↗
PubMed1998

Brachial plexus birth injuries and current management.

OBPP is a condition that, for the majority of patients, resolves spontaneously with appropriate nonoperative treatment. However, those patients who do not improve spontaneously now have a better chance for recovery owing to recent advances in microsurgery and nerve-transfer techniques. The most important aspect of therapy is timely recognition and referral.

Birth Injuries↗