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Biomedical subjects

E Aubert

Publications and source records attributed to E Aubert.

At least 19 recordsLinked to original sources
PubMed2003

Induced oscillations and the distributed cortical sources during the Wisconsin card sorting test performance in schizophrenic patients: new clues to neural connectivity.

Prefrontal dysfunction has been associated with schizophrenia. Activation during Wisconsin card sorting test (WCST) is a common approach used in functional neuroimaging to address this failure. Equally, current knowledge states that oscillations are basic forms of cells-assembly communications during mental activity. Promising results were revealed in a previous study assessing healthy subjects, WCST and oscillations. However, those previous studies failed to meet the functional integration of the network during the WCST in schizophrenics, based on the induced oscillations and their distributed cortical sources. In this research, we utilized the brain electrical tomography (variable-resolution brain electromagnetic tomography) technique to accomplish this goal. Task specific delta, theta, alpha and beta-2 oscillations were induced and simultaneously synchronized over large extensions of cortex, encompassing prefrontal, temporal and posterior regions as in healthy subjects. Every frequency had a well-defined network involving a variable number of areas and sharing some of them. Oscillations at 11.5, 5.0 and 30 Hz seem to reflect an abnormal increase or decrease, being located at supplementary motor area (SMA), left occipitotemporal region (OT), and right frontotemporal subregions (RFT), respectively. Three cortical areas appeared to be critical, that may lead to difficulties either in coordinating/sequencing the input/output of the prefrontal networks-SMA, and retention of information in memory-RFT, both preceded or paralleled by a deficient visual information processing-OT.

Adult↗
PubMed2003

Predicting outcome in acute stroke: a comparison between QEEG and the Canadian Neurological Scale.

OBJECTIVE: To determine and compare the predictive value of quantitative EEG (QEEG) and the Canadian Neurological Scale (CaNS), in patients with an acute cerebral stroke. METHODOLOGY: Twenty-eight patients were studied with the diagnosis of acute ischemic middle cerebral artery stroke, within the first 72 hours of clinical evolution. Thirty-seven EEGs and clinical evaluations were collected: 13 during the first 24 hours after stroke onset, 9 between 24-48 hours and 15 between 48-72 hours. The QEEG studied variables were: the Z values (maximum, minimum and the Z medians from the 5 nearest points to each one) of absolute energies (AE) from the 4 classic frequencies bands. The clinical scale showed a smaller percent of correct prognosis than QEEG variables. CONCLUSIONS: QEEG was demonstrated to be a powerful tool to predict the degree of residual functional disabilities after an acute ischemic stroke and showed a higher prognostic value than CaNS when they are performed within the first 72 hours of brain infarct.

Aged↗
PubMed2001

Invariant reversible QEEG effects of anesthetics.

Continuous recordings of brain electrical activity were obtained from a group of 176 patients throughout surgical procedures using general anesthesia. Artifact-free data from the 19 electrodes of the International 10/20 System were subjected to quantitative analysis of the electroencephalogram (QEEG). Induction was variously accomplished with etomidate, propofol or thiopental. Anesthesia was maintained throughout the procedures by isoflurane, desflurane or sevoflurane (N = 68), total intravenous anesthesia using propofol (N = 49), or nitrous oxide plus narcotics (N = 59). A set of QEEG measures were found which reversibly displayed high heterogeneity of variance between four states as follows: (1) during induction; (2) just after loss of consciousness (LOC); (3) just before return of consciousness (ROC); (4) just after ROC. Homogeneity of variance across all agents within states was found. Topographic statistical probability images were compared between states. At LOC, power increased in all frequency bands in the power spectrum with the exception of a decrease in gamma activity, and there was a marked anteriorization of power. Additionally, a significant change occurred in hemispheric relationships, with prefrontal and frontal regions of each hemisphere becoming more closely coupled, and anterior and posterior regions on each hemisphere, as well as homologous regions between the two hemispheres, uncoupling. All of these changes reversed upon ROC. Variable resolution electromagnetic tomography (VARETA) was performed to localize salient features of power anteriorization in three dimensions. A common set of neuroanatomical regions appeared to be the locus of the most probable generators of the observed EEG changes.

Adult↗
PubMed2000

Sources of abnormal EEG activity in brain infarctions.

EEGs from 16 patients with stroke in three different stages of evolution were recorded. EEG sources were calculated every 0.39 Hz by frequency domain VARETA. The main source was within the delta band in 2 out of 4 chronic patients, and in 67% of the patients in the acute or subacute stages when edema (cytotoxic or vasogenic) was present. Moreover, all patients showed abnormal activity in the theta band. Sources of abnormal activity in cortical or corticosubcortical infarcts were located in the cortex, surrounding the lesion. At the site of the infarct, a decrease of EEG power was observed. Sources of abnormal theta power coincided with edema and/or ischemic penumbra.

Adult↗
PubMed1999

Do specific EEG frequencies indicate different processes during mental calculation?

EEG recordings during mental calculation and a control task (with presentation of stimuli with similar physical characteristics to the arithmetic symbols) were obtained in 10 subjects. Narrow band analyses of the EEG and distributed sources for each EEG frequency were calculated using variable resolution electromagnetic tomography. Significant differences between the sources for arithmetic and control tasks were observed at 3.9 Hz within Broca's and left parietotemporal cortices, suggesting that this frequency may be related with the production of internal speech, storage and rehearsal of verbal working memory. Differences at 5.46 Hz within the right dorsolateral prefrontal cortex were considered to be associated to sustained attention. The decrease at 12.46 Hz within the left parietal cortex was interpreted as a sign of retrieval of arithmetic facts from long term memory.

Adult↗
PubMed1999

Sources of abnormal EEG activity in the presence of brain lesions.

In routine clinical EEG, a common origin is assumed for delta and theta rhythms produced by brain lesions. In previous papers, we have provided some experimental support, based on High Resolution qEEG and dipole fitting in the frequency domain, for the hypothesis that delta and theta spectral power have independent origins related to lesion and edema respectively. This paper describes the results obtained with Frequency Domain VARETA (FD-VARETA) in a group of 13 patients with cortical space-occupying lesions, in order to: 1) Test the accuracy of FD-VARETA for the localization of brain lesions, and 2) To provide further support for the independent origin of delta and theta components. FD VARETA is a distributed inverse solution, constrained by the Montreal Neurological Institute probabilistic atlas that estimates the spectra of EEG sources. In all patients, logarithmic transformed source spectra were compared with age-matched normative values, defining the Z source spectrum. Maximum Z values were found in 10 patients within the delta band (1.56 to 3.12 Hz); the spatial extent of these sources in the atlas corresponded with the location of the tumors in the CT. In 2 patients with small metastases and large volumes of edema and in a patient showing only edema, maximum Z values were found between 4.29 and 5.12 Hz. The spatial extent of the sources at these frequencies was within the volume of the edema in the CT. These results provided strong support to the hypothesis that both delta and theta abnormal EEG activities are the counterparts of two different pathophysiological processes.

Brain Edema↗
PubMed1998

[Percutaneous endoscopic gastrostomy for enteral nutrition. An evaluation of 50 patients].

The increased use of percutaneous endoscopic gastrostomy (PEG) for enteral nutrition, combined with the large number of different gastrostomy tubes available, should initiate a discussion about indications and practice. 50 patients who had had a gastrostomy for enteral nutrition performed at the Regional Hospital in Ostfold during the period 1993-96 have been evaluated. The method is safe and should be considered early if enteral nutrition is required. Few and only minor complications have been reported. Most adult patients will do well with a gastrostomy tube, the need for a button is presently being discussed. Users must be given detailed information on the management and use of a gastrostomy for enteral nutrition. An out-patient clinic for these patients--staffed by nurses--has shown good results. Percutaneous endoscopic gastrostomy for enteral nutrition can be used in the home, but the conditions must be well organized.

Adult↗
PubMed1997

Highly effective twice-daily triple therapies for Helicobacter pylori infection and peptic ulcer disease: does in vitro metronidazole resistance have any clinical relevance?

OBJECTIVES: To compare cure rates of Helicobacter pylori (H. pylori) infection, ulcer healing, and side effects of three simplified regimens of triple therapy in patients with peptic ulcer disease. METHODS: Two hundred thirty-one patients were prospectively randomized to receive either regimen OAM (omeprazole 20 mg b.i.d., amoxicillin 750 mg b.i.d., and metronidazole 400 g b.i.d.), OCM (omeprazole 20 mg b.i.d., clarithromycin 250 mg b.i.d., and metronidazole 400 mg b.i.d.), or BCM (bismuth subcitrate 240 mg b.i.d., clarithromycin 250 mg b.i.d., and metronidazole 400 mg b.i.d.), all for 10 days. Side effects were reported immediately afterward in a self-administered questionnaire. Upper endoscopy was carried out before treatment and 2 months after treatment. Three antral and three corpus biopsy specimens were analyzed microbiologically and with rapid urease test to determine the presence of H. pylori. Altogether 143 patients (62%) had an active ulcer at start of treatment. Metronidazole resistant (M-R) H. pylori strains were found in 30% of patients, while none had clarithromycin resistant (C-R) strains. RESULTS: According to intention-to-treat analysis, H. pylori cure rates were 91, 95, and 95% with OAM, OCM, and BCM, respectively (p = 0.63). In patients with metronidazole-sensitive (M-S) strains versus M-R strains, the cure rates were 96 versus 77% with OAM (p = 0.025), 94 versus 94% with OCM, and 94 versus 96% with BCM. Ulcer healing rates were 95, 94, and 92%, respectively (p = 0.91). There were no significant differences in side effects between the regimens, and only five patients (2%) had to stop the treatment prematurely. CONCLUSIONS: All treatment regimens were highly effective for cure of H. pylori infection and for ulcer healing. Metronidazole resistance reduced the efficacy of OAM, but was of no importance for the efficacy of OCM or BCM. Side effects were of minor importance.

Adult↗
PubMed1997

A comparison between omeprazole-based triple therapy and bismuth-based triple therapy for the treatment of Helicobacter pylori infection: a prospective randomized 1-yr follow-up study.

OBJECTIVES: To compare the efficacy and side effects of standard bismuth triple therapy with those of omeprazole-based triple therapy in patients with Helicobacter pylori infection and duodenal ulcer disease. METHODS: One hundred patients were prospectively recruited and randomized to receive either bismuth subnitrate 75 mg q.i.d., oxytetracycline 500 mg q.i.d., and metronidazole 400 mg b.i.d. (regimen BTM), or omeprazole 20 mg b.i.d., amoxicillin 750 mg b.i.d., and metronidazole 400 mg b.i.d. (regimen OAM), both for 14 days. Upper endoscopy (with antral biopsy specimens for microbiology and antral and corpus biopsy specimens for histology) was performed before treatment, after 2 months, and again 1 yr after treatment. Serum samples for serology (IgG) were taken. Patients with in vitro metronidazole-resistant (M-R) H. pylori strains were excluded. In a nonrandomized study, 41 patients with M-R strains were given either BTM or OAM. RESULTS: According to intention-to-treat analysis, H. pylori cure rates were 91% and 96% with BTM and OAM, respectively (p = 0.45). In the BTM group, the mean total side effect score was higher (p < 0.001), and more severe side effects were reported (32% vs. 4%, p < 0.001). In the nonrandomized group of patients with M-R strains, H. pylori cure rates were 88% and 67% with BTM and OAM, respectively. All of the successfully treated patients were still H. pylori-negative after 1 yr. CONCLUSIONS: Both treatment regimens were highly effective in curing H. pylori infection in patients with metronidazole-sensitive strains. Omeprazole-based triple therapy was tolerated better than standard bismuth-based triple therapy.

Adult↗
PubMed1994

Associative ERP effects with memories of artificial faces.

A previous study (Valdes-Sosa and Bobes, 1990) described a negative ERP component evoked by mis-matches in a face-feature matching task, using photographs of real faces. This component could be N400 (or an analogue), elicited by associative priming within a non-linguistic domain: that of face structure. To confirm this it is necessary to demonstrate that semantic/linguistic recoding was not a necessary condition in triggering the negativity. This means falsifying what we call the 'priming by proxy' hypothesis, and locating the triggering mis-match within face structure. In this paper subjects studied artificial schematic faces over several sessions, and 1 week later were presented with a face-feature matching task with simultaneous ERP recording. Since no semantic information or verbal labels were available, eliciting a mis-match negativity with these faces contradicts the 'priming by proxy' hypothesis. In a first experiment, in which the subjects learning was controlled through a face familiarity decision task, no significant mis-match negativity was found. However, in a second experiment in which learning was controlled through a forced-choice face-feature match, a significant mis-match negativity was found in the subsequent recording session. This result supports the idea that a component similar to N400 can be elicited by an associative mis-match restricted to the face-structural domain.

Adolescent↗
PubMed1989

On the evolution of Tn21-like multiresistance transposons: sequence analysis of the gene (aacC1) for gentamicin acetyltransferase-3-I(AAC(3)-I), another member of the Tn21-based expression cassette.

The aminoglycoside-3-O-acetyltransferase-I gene (aacC1) from R plasmids of two incompatibility groups (R1033 [Tn1696], and R135) was cloned and sequenced. In the case of R1033, it was shown that the aacC gene is coded by a precise insertion of 833 bp between the aadA promoter and its structural gene in a Tn21 related transposon (Tn1696). This insertion occurs at the same target sequence as that of the OXA-1 beta-lactamase gene insertion in Tn2603. Upstream of the aacC gene, we found an open reading frame (ORF) which is probably implicated in the site-specific recombinational events involved in the evolution of this family of genetic elements. These results provide additional confirmation of the role of Tn21 elements as naturally occurring interspecific transposition and expression cassettes.

Acetyltransferases↗
PubMed1988

Low-dose antacids or cimetidine for duodenal ulcer?

In a double-blind, randomized, multicenter trial 150 consecutive outpatients with endoscopically verified duodenal ulcer were treated with either a low-dose antacid regimen (1 tablet q.i.d.; acid-neutralizing capacity, 120 mmol/day), or cimetidine (800 mg nocte). After 4 wk of treatment control gastroscopy showed ulcer healing in 54 of 76 patients (71.1%) in the antacid group, as compared with 58 of 74 patients (78.4%) in the cimetidine-treated group. The difference in healing rate of 7.3% (95% confidence interval, -6.5% to +21.1%) was not statistically significant. The symptomatic effect, measured as number of days and nights with ulcer pain, was also quite similar in the two treatment groups. However, the number of days with pain was significantly lower in the first week of treatment in the antacid group (p less than 0.01). Thus, the efficacy of a low-dose antacid tablet regimen approximated that of cimetidine (800 mg nocte) in the treatment of duodenal ulcer patients.

Antacids↗
PubMed1987

Characterization of the sacQ genes from Bacillus licheniformis and Bacillus subtilis.

The sacQ gene from Bacillus licheniformis was cloned and expressed in Bacillus subtilis. Deletion analysis shows that it encodes a 46-amino-acid polypeptide homologous to the B. subtilis sacQ gene product. The polypeptide, when it is overexpressed, activates the expression of a number of target genes in B. subtilis, all encoding secreted enzymes: alkaline protease, levansucrase, beta-glucanase(s), xylanase, and alpha-amylase. The maximum stimulations measured for alkaline protease and levansucrase were by a factor of 70 and 50, respectively, when the sacQ gene from B. licheniformis was present on a multicopy plasmid in B. subtilis. The sacQ genes from B. subtilis and B. licheniformis, cloned in the same multicopy plasmid, were compared under the same conditions. The sacQ gene from B. licheniformis was more efficient than the sacQ gene from B. subtilis in producing the hypersecretion phenotype. The sacQ structural genes from B. subtilis and B. licheniformis were placed under the control of the same inducible promoter. Hypersecretion was specifically obtained under conditions of full induction of the promoter. The target site of levansucrase regulation by sacQ was identified as a 440-base-pair fragment located in the 5' noncoding region of sacB, suggesting transcriptional control.

Amino Acid Sequence↗
PubMed1985

Cloning and expression in Escherichia coli of the regulatory sacU gene from Bacillus subtilis.

The regulatory wild-type locus sacU, which has a pleiotropic effect in Bacillus subtilis, notably on the synthesis of secreted proteins, was obtained from a colony bank of Escherichia coli harboring recombinant cosmids representative of the B. subtilis genome. It was shown that the sacU gene is located on a 2.4-kilobase KpnI-EcoRI fragment and that the cloned sequence is homologous to the corresponding chromosomal DNA fragment. The wild-type phenotype was recovered after transformation of SacU-, SacUh, and SacU- Rec- strains with the recombinant cosmid, indicating that the sacU locus has been cloned in totality. The sacU gene was expressed in a minicell-producing E. coli strain, and it was shown that it coded for a 46-kilodalton protein. In addition to the hypersecretion of proteins, SacUh mutants were characterized by the presence of a 46-kilodalton protein in the membrane fraction in higher amounts than were found in the wild-type strain. These mutants were also devoid of a 36-kilodalton polypeptide corresponding to the flagellin subunit. Analysis of the mRNA content of a secreted protein (levansucrase) in SacU- and SacUh mutants strongly suggested that the pleiotropic action of the sacU gene on the synthesis of levansucrase is exerted at a posttranscriptional level in B. subtilis cells and is probably correlated with the mechanism of secretion of exoenzymes.

Bacillus subtilis↗
PubMed1985

Duodenal ulcer healing with four antacid tablets daily.

In a double-blind, randomized, multicenter trial in 80 consecutive outpatients with endoscopically verified duodenal ulcer, we have tested the ulcer-healing efficacy of a quite low dose of antacids, given only four times daily. The patients received one chewable aluminum-magnesium-antacid tablet (buffering capacity, 30 mmol/tablet) or placebo 1 h after meals and at bedtime. Re-endoscopy after 4 weeks of treatment showed healed ulcer in 28 of 38 patients (74%) in the antacid group, compared with 11 of 38 patients (29%) in the placebo group (p less than 0.001). The number of days and nights with ulcer pain was significantly less in the antacid group than in the placebo group during the treatment period. Thus, only four antacid tablets a day, with a total buffering capacity of 120 mmol/day, significantly promote duodenal ulcer healing and pain relief.

Adult↗
PubMed1980

[Urinary-blood delta PCO2 in renal tubular acidosis (author's transl)].

A state of renal tubular acidosis has been produced in rats by the administration of sodium maleate or acetazolamide (proximal tubular acidosis) and of lithium chloride of amiloride (distal tubular acidosis). During progressive alkaline diuresis, delta PCO2 (urine minus blood PCO2) increases significantly in rats presenting proximal tubular acidosis. Delta PCO2 is significantly depressed in rats presenting distal tubular acidosis. In well defined conditions of bicarbonate or phosphate excretion, delta PCO2 is a valuable index of distal ion secretion.

Acetazolamide↗