Search PubMed⌕ Search

Biomedical subjects

F Vidal

Publications and source records attributed to F Vidal.

At least 109 records · Page 6Linked to original sources
PubMed1996

Brain activation induced by estimation of duration: a PET study.

Duration information about a visual stimulus requires processing as do other visual features such as size or intensity. Using positron emission tomography, iterative H215O infusions, and statistical parametric mapping, we investigated the neural correlates of time processing. Nine normal subjects underwent six serial rCBF. Three tasks were studied: (a) A temporal generalization task (D task) in which the subjects had to judge (by pressing one of two keys) whether the duration of the illumination of a green LED was equal to or different from that of a previously presented standard; (b) An intensity generalization task (I task) in which the judgment concerned the intensity of the LED; and (c) A control task (C task) in which the subjects had to press one of the two keys at random in response to LED illumination. A significant increase in rCBF during the D task, compared to that during the C task, was observed in right prefontal cortex, right inferior parietal lobule, anterior cingulate cortex, vermis, and a region corresponding to the left fusiform gyrus. A significant increase in rCBF during the I task, compared to that during the C task, was observed in right prefontal cortex, right inferior parietal lobule, right extrastriate cortex, anterior cingulate cortex, left inferior parietal lobule, vermis, and two symmetrical regions corresponding to the fusiform gyri. No significant activation was observed in the D task when compared to that in the I task. We propose that these cortical maps are best explained by the recruitment of visual attention and memory structures, which play a major role in prospective time judgements as indicated by behavioral studies. The data also suggest that the temporal dimension of a visual stimulus is processed in the same areas as other visual attributes.

Adult↗
PubMed1996

[Pleural effusion as initial presentation of rheumatoid arthritis. Cytological diagnosis].

A 24-year-old woman with an unremarkable history presented with a large right-sided pleural effusion. Analysis of the pleural fluid showed a sterile exudate with a low sugar level. Complementary analyses were unable to pinpoint the etiology. The effusion was drained and the patient was released with no specific diagnosis. Nine months later the effusion recurred and the initial laboratory analyses were the same. Pleural fluid cytology revealed the presence of an amorphous necrotic background and non-small cells with multiple nuclei, two signs that constitute part of the pathognomonic triad of rheumatoid pleural effusions, the third characteristic benign fusiform histocytes. The biochemical characteristics of the pleural fluid thus suggested rheumatoid pleural effusion, and cytology confirmed the diagnosis. Corticoid therapy effected spectacular recovery, but when the dose was reduced, rheumatoid symptoms presented in the joints. Rheumatoid arthritis should be considered as a possible explanation for unexplained pleural effusion. Cytology must be used for diagnosis.

Adult↗
PubMed1996

Nimodipine fails to enhance the analgesic effect of slow release morphine in the early phases of cancer pain treatment.

We assessed nimodipine's ability to increase the analgesic effect of morphine in 32 patients suffering from cancer pain in a double-blind, placebo controlled cross-over study. Morphine administration began a few days before the start of the study. The analgesic effects of two combinations were compared: morphine (M) plus placebo (P) and morphine plus 90 mg/24 h of nimodipine (N). The study lasted 8 days, including the wash-out period, and the following sequence of treatments was applied: M + P or M + N on days 1, 2 and 3; only M on days 4 and 5; and M + N or M + P on days 6, 7 and 8. Morphine dose was individualised according to the intensity of the patient's pain and the same dose was maintained throughout the study period. Analgesic response was evaluated using four 10 cm visual analogue scales of quantitative variables for pain intensity, pain relief, sleep quality and mood. A verbal rating of qualitative variables was also scored following validated descriptors of pain in the Spanish language. No significant statistical differences were found in analgesic effect between combined treatment with nimodipine or placebo, as measured on any of the scales. In order to take into account both the short duration of treatment (8 days), and nimodipine's pharmacokinetic characteristics (half-life of 6 h and steady state of 36 h), we compared treatment with nimodipine or placebo on the third day of use, at which time, likewise, there were no statistically significant differences on any of the scales. However, when the same statistical tests were used for comparison of results with pre-treatment baseline values, highly significant differences between mean scores on the scales for pain relief and pain intensity were found. Based on these negative results we conclude that nimodipine given orally at a dose of 30 mg every 8 h does not enhance analgesia when associated with morphine in the early phases of treatment for cancer pain. Our study also gives clear evidence of a placebo effect.

Administration, Oral↗
PubMed1996

Absence of an early pre-emptive effect after thoracic extradural bupivacaine in thoracic surgery.

We have determined if thoracic extradural block before surgical incision for thoracotomy produces pre-emptive analgesia. Using a double-blind, placebo-controlled, crossover design, 45 patients (ASA II-III) undergoing posterolateral thoracotomy for lung resection were randomized to one of three groups: group 1 received 0.5% bupivacaine and adrenaline 1/200,000 (B+E) 8 ml through a thoracic extradural catheter (tip T3-T5) 30 min before skin incision and saline 8 ml 15 min after skin incision; group 2 received saline 8 ml extradurally before incision and B+E 8 ml after incision; group 3 received saline 8 ml extradurally before and after incision. General anaesthesia was induced and maintained with propofol, alfentanil and atracurium. The alfentanil infusion was stopped before chest closure and fentanyl 50 micrograms in saline 10 ml was given extradurally. Patient-controlled extradural analgesia (PCEA) was commenced with 0.125% bupivacaine, adrenaline 1/400,000 and fentanyl 6 micrograms ml-1 (continuous rate of 2 ml h-1 and supplementary doses of 0.5 ml per 6 min). Visual analogue scale (VAS) scores (recorded at rest, on mobilization and after cough), verbal rating scale (VRS) (recorded at rest), number of successful PCEA demands and complications were measured during the first 48 h after operation. There was no significant difference between groups, either in PCEA requirements (P > 0.21) or in VAS scores (either at rest, during mobilization of the ipsilateral arm of surgery or after cough). No significant differences between groups were found in the VRS. Thoracic extradural block with bupivacaine did not produce an early preemptive effect after thoracotomy.

Adult↗
PubMed1996

Incidence of chromosome 21 disomy in human spermatozoa as determined by fluorescent in-situ hybridization.

We have evaluated the incidence of chromosome 21 disomy in decondensed sperm heads from nine normal men using a locus-specific DNA probe for chromosome 21, and a centromeric probe for chromosome 6 as a control. The results show that the incidence of chromosome 21 disomy (0.38%) is significantly higher than disomy for chromosome 6(0.14%). No differences were found among the individuals analysed.

Adult↗
PubMed1996

Thoracic epidural anesthesia via the lumbar approach in infants and children.

BACKGROUND: In upper abdominal or chest surgery, the segmental approach to thoracic epidural space has the advantage of reducing the total dose of local anesthetic needed. This approach, however, is associated with greater risk of neurologic damage or dural puncture. The aim of this study was to assess the success and the degree of difficulty in advancing a 19-G catheter from the lumbar epidural space to the thoracic level in patients aged 0-96 months. METHODS: In 39 patients undergoing abdominal surgery, the cutaneous distance between the L4-L5 and T10-T11 interspaces was measured, and an appropriate length of 19-G catheter was inserted into the epidural space through an 18-G Tuohy needle with bevel directed cephalad. The intent was to advance the full length of catheter measured to reach the objective. The tips were observed radiologically, and all those positioned cephalad to the T12 level were considered well placed. The degree of difficulty in advancing the catheter was classified as easy, difficult, or impossible. Complications reported were vascular and/or spinal puncture and difficulty removing the catheter. RESULTS: The catheter tip reached T10-T12 in 7 patients, L2 in 1, L3 in 8, and L4-L5 in 23. Forty-eight percent of the catheters described as easily advanced remained at the L4-L5 level, and only 22% reached the desired level. Difficult insertions occurred in eight patients, in whom the objective was never reached. One case of intravascular insertion was reported. All catheters were removed without difficulty. CONCLUSIONS: The 19-G catheter is inappropriate for use in reaching the thoracic epidural space by the lumbar approach. Easy entrance of a catheter is not a reliable sign of having reached the desired level.

Anesthesia, Epidural↗
PubMed1995

Cloning of the laminin alpha 3 chain gene (LAMA3) and identification of a homozygous deletion in a patient with Herlitz junctional epidermolysis bullosa.

Laminin 5 and laminin 6 are basement membrane proteins synthesized by the basal cells of stratifying squamous epithelia. Altered expression of laminin 5 has been associated with Herlitz junctional epidermolysis bullosa (H-JEB), a severe epidermal blistering disorder inherited as an autosomal recessive disease. We have isolated cDNA clones encoding the alpha 3 chain of laminin 5 and searched for mutations in the LAMA3 gene in H-JEB patients. In one H-JEB family, an affected individual exhibited drastically reduced immunoreactivity to antibodies directed against the alpha 3 chain of laminin 5 and an impaired expression of the corresponding mRNA transcripts. RT-PCR analysis of mRNA extracted from the proband's keratinocytes identified a homozygous single basepair deletion in the transcripts encoding the laminin alpha 3A and alpha 3B isoforms. The mutation causes a frameshift and premature termination codon in both alleles of the LAMA3 gene. Inheritance of the clinical H-JEB phenotype was consistent with the segregation of the mutated allele in the family. We also report the identity of the alpha chains of laminin 5 and epiligrin and provide evidence that LAMA3 transcripts are distinct from the laminin 6 alpha chain mRNA.

3T3 Cells↗
PubMed1995

Degradation of fluorescent and radiolabelled sphingomyelins in intact cells by a non-lysosomal pathway.

The aim of the present study was to investigate the role of the entitled neutral, sphingomyelinase in the non-lysosomal pathway of sphingomyelin degradation by intact cells (Spence et al. (1983) J. Biol. Chem. 258, 8595-8600; Levade et al. (1991) J. Biol. Chem. 266, 13519-13529). The uptake and degradation of sphingomyelin by intact living cells was studied using cell lines exhibiting a wide range of activity levels of acid, lysosomal and neutral sphingomyelinases as determined in vitro on cell homogenates by their respective standard assays. For this purpose, neuroblastoma, skin fibroblasts, lymphoid and leukemic cell lines, some of them derived from patients with Niemann-Pick disease (deficient in the acid, lysosomal sphingomyelinase) were incubated with radioactive, [oleoyl-3H]sphingomyelin or fluorescent, pyrene-sulfonylaminoundecanoyl-sphingomyelin. Either compound was taken up by a pathway which was not receptor-mediated and hydrolyzed by all intact cells, including those derived from Niemann-Pick disease patients. Moreover, their degradation by the intact cells was not inhibited by treatment with chloroquine, indicating hydrolysis by a non-lysosomal sphingomyelinase. The intracellular sphingomyelin degradation rates showed no correlation with the activity of the 'classical' neutral sphingomyelinase as determined in vitro. In particular, fibroblasts derived from Niemann-Pick patients lacking the lysosomal sphingomyelinase, and having no detectable in vitro activity of the 'classical' neutral sphingomyelinase, were able to degrade the exogenously supplied sphingomyelins. Indeed, in vitro these cells were shown to exhibit neutral, magnesium- and dithiothreitol-dependent sphingomyelinase activities, that might contribute to the non-lysosomal pathway for sphingomyelin degradation to ceramide in intact cells.

Bridged-Ring Compounds↗
PubMed1995

USF binds to the APB alpha sequence in the promoter of the amyloid beta-protein precursor gene.

The APB alpha domain in the amyloid beta-protein precursor (APP) promoter contains a nuclear factor binding domain with the core recognition sequence TCAGCT-GAC. Proteins in nuclear extracts from brain and numerous cell lines bind to this domain and it contributes approximately 10-30% to the basal APP promoter activity. Included in this domain is the CANNTG motif, which is recognized by basic helix-loop-helix transcription factors. The same motif is also present in the CDEI element of the yeast centromere and in the adenovirus major late promoter (AdMLP). Here we present evidence based on thermostability, relative binding affinity, eletrophoretic mobility and antibody recognition that the cellular proteins that bind to the APB alpha and CDEI motifs are USF. However, the relative binding affinity for the motifs is different. The affinity of USF for AdMLP is approximately 20-fold higher than for the APB alpha sequence and 5-fold higher than for the CDEI sequence. Mutational analysis suggested that the primary determinant for USF binding affinity resides within the octamer CAGCTGAC, which is composed of the E-box consensus sequence CANNTG followed by the dinucleotide AC. The human homolog of the mouse CDEI binding protein did not bind to either the CDEI sequence or APB alpha.

Adenoviridae↗
PubMed1995

Programming the duration of a motor sequence: role of the primary and supplementary motor areas in man.

Event-related potentials were recorded in a reaction time (RT) paradigm, where the duration of a learned interval (either 0.7 s or 2.5 s) delimited by two brief button-presses was to be accurately controlled. A preparatory signal (PS) either did not give or gave prior information concerning the duration of the following response (neutral condition or primed conditions, respectively). In the latter case, the information was either validated (valid condition) or invalidated (invalid condition) by the response signal (RS). When duration was not known in advance (invalid and neutral conditions), RTs were longer before a response of short than long duration. This difference was not found under the valid condition. During the preparatory period (PP), the amplitude of the contingent negative variation (CNV) was larger when the duration was primed than when it was not. A larger CNV appeared when the PS primed a short rather than a long duration. This effect occurred in the early part of the PP over the supplementary motor area (SMA) and in its latest part over the primary motor area (MI). The RT and the electrophysiological pattern were interpreted as revealing the occurrence of programming operations regarding the temporal dimension of the response. The time course of the CNV over the SMA and MI suggested that these two areas were hierarchically organized. Between the RS and the onset of the response, differences probably related to programming effects were still found over MI: the activities were larger under the valid than under the neutral condition. However, no sign of deprogramming (expected in the invalid condition) was observed: similar amplitudes were found under the neutral and invalid conditions. Deprogramming operations seemed to be postponed during response execution where the invalid condition evoked larger activities than the two other conditions over the SMA. Finally, MI but not the SMA yielded a Bereitschaftpotential before the second press ending the response (i.e., during response execution). These results suggest that the duration of a motor response can be a part of the motor program and that the SMA plays a major role in programming processes but not in response execution, contrary to MI.

Algorithms↗
PubMed1995

Cytogenetic studies of oocyte fusion products.

We describe for the first time the cytogenetic characteristics of mouse 'embryos' obtained by oocyte fusion (oocyte fusion products; OFP). Our results indicate that, after fusion, meiosis II is resumed correctly, with extrusion of two haploid polar bodies, and that metaphase synchronisation of the two haploid sets and chromosome segregation during the first cleavage are also normal.

Animals↗
PubMed1995

Early mouse preimplantation development is unaffected by microinjection of metallothionein antibodies.

Polyclonal antibodies that cross-react with rodent metallothionein I (MT I) and metallothionein II (MT II) were microinjected in 1-cell and 2-cell mouse embryos, into either the cytoplasm or the nucleus. Regardless of the experimental treatment, mouse embryo development in vitro was not affected and most of the embryos cleaved normally until the morula stage. The results suggest that metallothionein is not essential for normal mouse early preimplantational development, in agreement with recent studies in mice with inactivated MT I and MT II genes.

Animals↗
PubMed1995

Integrin beta 4 mutations associated with junctional epidermolysis bullosa with pyloric atresia.

Pyloric atresia associated with junctional epidermolysis bullosa (PA-JEB), is a rare inherited disorder characterized by pyloric stenosis and blistering of the skin as primary manifestations. We demonstrate that in one PA-JEB patient the disease resulted from two distinct mutations in the beta 4 integrin gene alleles. The paternal mutation consists of a one base pair deletion causing a shift in the open reading frame, and a downstream premature termination codon. The maternal mutation occurs in a donor splice site, and results in in-frame exon skipping involving the cytoplasmic domain of the polypeptide. Our results implicate mutations in the beta 4 integrin gene in some forms of PA-JEB.

Alleles↗