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F Palacios

Publications and source records attributed to F Palacios.

18 recordsLinked to original sources
PubMed2002

Wavelet transform analysis of heart rate variability during myocardial ischaemia.

Analysis of heart rate variability (HRV) is a valuable, non-invasive method for quantifying autonomic cardiac control in humans. Frequency-domain analysis of HRV involving myocardial ischaemic episodes should take into account its non-stationary behaviour. The wavelet transform is an alternative tool for the analysis of non-stationary signals. Fourteen patients have been analysed, ranging from 40 to 64 years old and selected from the European Electrocardiographic ST-T Database (ESDB). These records contain 33 ST episodes, according to the notation of the ESDB, with durations of between 40s and 12 min. A method for analysing HRV signals using the wavelet transform was applied to obtain a time-scale representation for very low-frequency (VLF), low-frequency (LF) and high-frequency (HF) bands using the orthogonal multiresolution pyramidal algorithm. The design and implementation using fast algorithms included a specially adapted decomposition quadrature mirror filter bank for the frequency bands of interest. Comparing a normality zone against the ischaemic episode in the same record, increases in LF (0.0112 +/- 0.0101 against 0.0175 +/- 0.0208 s2 Hz(-1); p<0.1) and HF (0.0011 +/- 0.0008 against 0.00 17 +/- 0.0020 s2 Hz(-1); p<0.05) were obtained. The possibility of using these indexes to develop an ischaemic-episode classifier was also tested. Results suggest that wavelet analysis provides useful information for the assessment of dynamic changes and patterns of HRV during myocardial ischaemia.

Adult↗
PubMed2001

An essential role for ARF6-regulated membrane traffic in adherens junction turnover and epithelial cell migration.

We describe a novel role for the ARF6 GTPase in the regulation of adherens junction (AJ) turnover in MDCK epithelial cells. Expression of a GTPase-defective ARF6 mutant, ARF6(Q67L), led to a loss of AJs and ruffling of the lateral plasma membrane via mechanisms that were mutually exclusive. ARF6-GTP-induced AJ disassembly did not require actin remodeling, but was dependent on the internalization of E-cadherin into the cytoplasm via vesicle transport. ARF6 activation was accompanied by increased migratory potential, and treatment of cells with hepatocyte growth factor (HGF) induced the activation of endogenous ARF6. The effect of ARF6(Q67L) on AJs was specific since ARF6 activation did not perturb tight junction assembly or cell polarity. In contrast, dominant-negative ARF6, ARF6(T27N), localized to AJs and its expression blocked cell migration and HGF-induced internalization of cadherin-based junctional components into the cytoplasm. Finally, we show that ARF6 exerts its role downstream of v-Src activation during the disassembly of AJs. These findings document an essential role for ARF6- regulated membrane traffic in AJ disassembly and epithelial cell migration.

ADP-Ribosylation Factor 6↗
PubMed2001

[Macroscopic and microscopic study of the right coronary artery after radiofrequency catheter ablation of cavotricuspid isthmus in an experimental model].

INTRODUCTION AND OBJECTIVES: The right coronary artery (RCA) is found in the AV groove, just below the ablation target of atrial flutter, the cavotricuspid isthmus (ICT). After radiofrequency (RF) ablation with standard catheters, there have been no reports of complications, but it may not be successful in 10% of the cases. However, the use of irrigated tip catheters, which create deeper lesions, might potentially damage the coronary tree. METHODS: We analyzed the effects of ICT RF ablation on the coronary tree, with macroscopic and microscopic anatomopathological study. Ablation on ICT was performed using an irrigated tip catheter in 16 pigs and was randomly compared with a standard ablation catheter. There were no clinical problems, modifications of ST or new arrhythmias during the ablation. The heart was extracted at 1 week. RESULTS: The macroscopic study demonstrated that the right coronary artery was preserved, along the ICT, surrounded by the epicardial fat. The microscopic study showed an inflammatory reaction in the epicardial fat that reached the adventitia of the coronary artery, but never produced necrosis in 14 cases. The muscular wall of the artery had signs of focal inflammation without endothelium involvement in 2 cases. However, we found a subepicardial vein completely damaged by the radiofrequency. CONCLUSIONS: Although the right coronary artery is located just below the isthmus, no necrosis was observed in any case. However, there was an inflammatory reaction that focally reached the muscular wall. The veins may be damaged in RF ablation, perhaps due to the different blood flow of each vessel.

Animals↗
PubMed2001

Randomized comparison of efficacy of cooled tip catheter ablation of atrial flutter: anatomic versus electrophysiological complete isthmus block.

There is a subset of patients with failed ablation of the cavotricuspid isthmus (CTI) using standard catheters and with 10% of the patients having recurrences. The purpose of this study was to compare the cooled and standard ablation with regard to acute successful electrophysiological achievement of bidirectional isthmus block and the subacute anatomic characteristics of the lesions. This randomized, experimental study compares the effects of ablation on the isthmus using a cooled catheter with those of a standard ablation catheter in 16 pigs. In 12 animals, CTI block was achieved after ablation (8/8 cooled and 4/8 standard). In two animals, it was not possible to achieve complete isthmus block and two had persistent slow conduction (all four using the standard catheter). After 1 week, the animals were slaughtered. The size of the lesion was greater with the irrigated tip catheters. Transmural lesions were found in 14 animals. A complete line of anatomic isthmus block was not documented after thefirst line in six animals, four with the standard and two with the cooled catheter. A conduction block was never present across gaps > or = 5 mm. In conclusion cooled catheters achieved a complete line of electrophysiological and anatomical block in a significantly higher percentage than the standard catheters.

Animals↗
PubMed2000

[Hairy cell leukemia. An alternative method for the detection of minimal residual disease using flow cytometry].

In patients with hairy cell leukemia (HCL) who received chemotherapeutic treatment and achieved complete remission (CR), minimal residual disease (MRD) can be detected in bone marrow biopsies using immunohistochemical (IHC) techniques. In this study, we investigated the value of flow cytometry (FCM) and IHC to detect MRD and to establish whether MRD+ could predict relapse. A total of 15 HCL patients in CR were studied. Samples of bone marrow (BM) and peripheral blood (PB) were processed by FCM with triple staining of the following monoclonal antibodies (mAbs): CD20, CD22, CD11c, CD103, CD25, anti-Kappa and anti-Lambda light chains. Reference values were obtained from normal samples of peripheral blood and bone marrow. FCM detected MRD in 64% of the patients. BM samples were more demonstrative than peripheral blood for MRD detection in HCL. IHC was performed in paraffin-embedded BM biopsies using CD20 and DBA44 mAbs. MRD+ was detected in 46% of patients. Although not statistically significant, FCM appeared more sensitive compared with IHC. Detection of MRD by either of these methods in our series did not predict hematological relapse. The results show that FCM is a useful alternative method to detect MRD in HCL and that a longer, follow-up is required to establish the predictive outcome of MRD+ patients.

Antibodies, Monoclonal↗
PubMed1999

A problem-solving method for 'unprotocolised' therapy administration task in medicine.

This paper describes a problem-solving method for modelling the 'unprotocolised' treatment administration task in medicine. We argue that there are medical domains in which no well-established standard treatment protocols exist, and the physician has to decide on the therapy that is to be applied to each patient, in function of a set of therapeutic objectives to be fulfilled. For this reason, we propose the modelling of this type of task adapting the generic class of problem resolution methods for design task, labelled as Propose-Critique-Modify (PCM). In this paper, we are presenting a model of expertise which has been developed using the basic modelling components of the CommonKADS methodology.

Artificial Intelligence↗
PubMed1997

SUTIL: intelligent ischemia monitoring system.

SUTIL is an intelligent monitoring system for intensive and exhaustive follow up of patients in coronary care units. This system processes electrocardiographic and hemodynamic signals in real time, with the main objective of detecting ischemic episodes. In this paper, we describe the tasks included in SUTIL. In addition to basic tasks, those at higher levels will also be presented. Some of these latter tasks attempt to mimic, to some extent, the way in which the human expert operates.

Algorithms↗
PubMed1994

Speciation and paraphyly in western Mediterranean hares (Lepus castroviejoi, L. europaeus, L. granatensis, and L. capensis) revealed by mitochondrial DNA phylogeny.

Mitochondrial DNA (mtDNA) variation among specimens of the northwestern African hare (Lepus capensis schlumbergeri) and three European hares sampled in Spain (L. castroviejoi and L. granatensis, which are endemic to the Iberian Peninsula, and L. europaeus) was analyzed using seven restriction endonucleases. Fourteen haplotypes were found among the 34 animals examined. Restriction site maps were constructed and the phylogeny of the haplotypes was inferred. mtDNA of L. capensis was the most divergent, which is consistent with its allopatric African distribution and with an African origin of European hares. We estimated that mtDNA in hares diverges at a rate of 1.5-1.8% per MY assuming that the European and African populations separated 5-6 MYBP. Maximum intraspecies nucleotides divergences were 1.3% in L. capensis, 2.7% in L. castroviejoi, and 2.3% in L. granatensis but 13.0% in L. europaeus. The latter species contained two main mtDNA lineages, one on the branch leading to L. castroviejoi and the other on that leading to L. granatensis. The separation of these two lineages from the L. castroviejoi or L. granatensis lineages appears to be much older than the first paleontological record of L. europaeus in the Iberian peninsula. This suggests that the apparent polyphyly of L. europaeus is due not to secondary introgression, but to the retention of ancestral polymorphism in L. europaeus. The results suggest that L. europaeus either has evolved as a very large population for a long time or has been fractionated. Such a pattern of persistence of very divergent lineages has also been reported in other species of highly mobile terrestrial mammals. As far as mtDNA is concerned. L. europaeus appears to be the common phylogenetic trunk which has diversified during dispersion over the European continent and from which L. castroviejoi and L. granatensis speciated separately in southwest Europe.

Animals↗
PubMed1993

[Delay in caring for patients with precordial pain].

OBJECTIVES: Estimate the differences in the time of arrival at the Intensive Care Unite (ICU) among patients with previous++ infarction versus first infarction ones. DESIGN: Transversal retrospective study. SETTING: General Hospital of Elche. PATIENTS AND OTHER PARTICIPANTS: 622 diagnosed of infarction between 1984-1990. MEASUREMENTS AND MAIN RESULTS: The sample was divided into two groups according to whether having previous infarction or not. In each patient we registered age, sex, initial killip, initial CPK, maximum CPK, year of admission and time from beginning of symptoms till ICU arrival. None of the groups we studied showed significant differences in which refers to times to arrival at ICU. Initial CPK was lower in those who had previous infarction (p = 0.023) (obtained at the emergency ward). CONCLUSIONS: We concluded that patients with previous infarction arrive at hospital before those first infarction (lower CPK in emergency ward), but assistance protocols even the elapsed time when arriving at ICU. We did not find any factors which joined with time value in a significant way.

Aged↗
PubMed1989

Dysfunction of the monocyte-macrophage system in the idiopathic minimal change nephrotic syndrome.

We studied the function of phagocytes and the distribution of lymphocyte subpopulations in 23 patients with Idiopathic Minimal Change Nephrotic Syndrome. All the patients were in relapse at the time of the study. The latter was performed before specific therapy was started. Our control group consisted of 26 normal children who were studied while undergoing routine analysis prior to plastic surgery. Polymorphonuclear leukocytes from the patients showed no alterations in their ability to ingest and to kill candidas. On the contrary, peripheral blood monocytes had a normal phagocytic function with a decreased candidacidal activity when compared to normal controls (p less than 0.001). No correlation was found between serum immunoglobulin levels and the monocyte lytic function. The absolute number of B lymphocytes was significantly increased (p less than 0.05), whereas the absolute number of total lymphocytes, T lymphocytes and T4+ and T8+ cell subsets did not differ from those of the age-matched normal controls. Natural killer cells were functionally normal.

Child↗
PubMed1989

[Immunologic studies in thalassemia major].

It is accepted that the immune alterations in patients with thalassemia major (TM) are secondary to the continuous transfusion-related antigenic stimulation together with iron overload. We evaluated the immune status of TM patients and found quantitative alterations in the distribution of peripheral blood lymphocyte subpopulations as well as functional alterations in natural killer (NK) cytotoxicity, B-cell differentiation, T-cell immunoregulation and phagocyte functional activities. TM patients, 10 years old or younger, have a lymphocyte profile and phagocytic activity similar to normal controls. Non-splenectomized thalassemic patients, older than 10, present lymphocytosis due to an increase in B lymphocytes and with splenectomy the T-CD8+ lymphocytes increase. With respect to phagocytes, the capacity to ingest candida is preserved while the candidacidal activity and the generation of toxic oxygen metabolites during the respiratory burst are diminished, and are inversely proportional with age and serum ferritin concentration, that is, older in age and higher in iron overload, more profound are the phagocyte dysfunctions. The altered B-cell function, the dysfunction of T immunoregulatory cells and the defective NK activity observed in TM patients were independent of the age of the patients and they were observed even in children younger than 10 years old and in general are attributed to blood transfusions. Moreover, there are some alterations that thalassemic carriers can express such as a defect at the level of NK and at B-cell function regulations, suggesting a possible genetic origin. Although complex, TM constitutes a human model that allows the dissection of specific immune defects, involving multiple factors, and can provide a better comprehension of how this complex immunoregulatory system works.

Humans↗
PubMedDate not supplied

Fuzzy logic in a patient supervision system.

A patient supervision system in progress for intensive and coronary care units, focused on patients with acute myocardial infarct is briefly described particularly regarding the role that fuzzy logic is playing in its design, and why this is so.

Artificial Intelligence↗
PubMedDate not supplied

[Hepatic hemorrhagic infarction in eclampsia and HELLP Syndrome associated with the antiphospholipid syndrome].

A 33 year-old woman developed eclampsia with HELLP syndrome. Laboratory results revealed lupus anticoagulant and anticardiolipin antibodies. Imaging tests showed liver and spleen infarctions. The patients was given enoxaparin and supportive care and there was a good evolution. We discuss some aspects about liver infarction and its association with toxemia of pregnancy and the antiphospholipid syndrome.

Adult↗
PubMedDate not supplied

The muscle inhibitory period by transcranial magnetic stimulation. Study in stroke patients.

Motor evoked potentials (MEPs) elicited over hand muscles by transcranial magnetic stimulation (TMS) were studied in healthy individuals and, bilaterally, in patients with cerebral infarction. Conduction time of the central motor pathways (CMCT), threshold intensity, and amplitude of the MEPs were correlated with recovery motor hand function after stroke. Following MEPs by TMS during tonic muscle contraction, there is a transient suppression of muscle action. This inhibitory period (IP) was significantly shorter in the upper paretic limb of stroke patients with spasticity than in normal limb of the patients and healthy individuals. Shortening of the IP duration was correlated to degree of upper limb spasticity (Ashworth scale) and may be due to supraspinal level reduction of the inhibitory function. The IP study contributes to a better quantification of the hand function in stroke patients.

Adult↗