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Biomedical subjects

J Izquierdo

Publications and source records attributed to J Izquierdo.

At least 19 recordsLinked to original sources
PubMed2006

Analysis of bifurcation phenomena in the electron internal transport barrier in the large helical device.

The electron internal transport barrier (eITB) formation in the Large Helical Device (LHD) is studied with the transport code TOTAL and a GyroBohm-like model. The reduction of anomalous transport by the E x B shear has been introduced by means of the factor [1 + (tauomega(ExB))(gamma)](-1). Simulation results show a clear critical transition between plasma regimes with rather flat electron temperature profiles (non-) to a steeped one (with eITB) when average density is low enough. With the aim of studying the eITB formation as a phase transition phenomenon, the electron average density is taken as the control parameter and the E x B shearing rate as the order parameter. Results show how the eITB formation in LHD is compatible with a continuum phase transition with critical exponent beta = 0.40.

Journal Article↗
PubMed2005

Analysis of forced wheezes in asthma patients.

BACKGROUND: Spirometric parameters can be normal in many stable asthma patients, making a diagnosis difficult at certain times in the course of disease. OBJECTIVES: The present study aims to find differences and similarities in the acoustic characteristics of forced wheezes among asthma patients with and without normal spirometric values. METHODS: Eleven chronic asthma patients (8 men/3 women) with moderate-to-severe airway obstruction (FEV1 48.4%), 9 stable asthma patients (6 males/3 females) with normal spirometry (FEV1 84.0%) and a positive methacholine test and 14 healthy subjects (8/6) were enrolled in the study. A contact sensor was placed on the trachea, and wheezes were detected by a modified Shabtai-Musih algorithm in a time-frequency representation. RESULTS: More wheezes were recorded in obstructive asthma patients than in stable asthma and control subjects: nonstable asthma 13.6 (13.3), stable asthma 3.5 (3.0) and control subjects 2.5 (2.1). The mean frequency of all wheezes detected was higher in control subjects than in either stable or non-stable asthma patients. The change in the total number of wheezes after terbutaline inhalation was more pronounced in nonstable asthma patients than in stable asthmatics and control subjects. CONCLUSIONS: This study confirms that wheeze recording during forced expiratory maneuvers can be a complementary measure to spirometry to identify asthma patients.

Acoustics↗
PubMed2003

Risk factors of readmission to hospital for a COPD exacerbation: a prospective study.

BACKGROUND: Exacerbations of chronic obstructive pulmonary disease (COPD) are a leading cause of admission to hospital among men in many countries, although the factors causing exacerbations are largely unknown. The association between readmission for a COPD exacerbation and a wide range of modifiable potential risk factors, after adjusting for sociodemographic and clinical factors, has been assessed. METHODS: Three hundred and forty patients with COPD recruited during an admission for an exacerbation in four tertiary hospitals in the Barcelona area of Spain were followed for a mean period of 1.1 years. Information on potential risk factors, including clinical and functional status, medical care and prescriptions, medication adherence, lifestyle, health status, and social support, was collected at the recruitment admission. A Cox's proportional hazards model was used to obtain independent relative risks of readmission for COPD. RESULTS: During the follow up period 63% of patients were readmitted at least once, and 29% died. The final multivariate model showed the following risk (or protective) factors: > or =3 admissions for COPD in the year before recruitment (hazard ratio (HR)=1.66, 95% CI 1.16 to 2.39), forced expiratory volume in 1 second (FEV(1)) percentage predicted (0.97, 95% CI 0.96 to 0.99), oxygen tension (0.88, 95% CI 0.79 to 0.98), higher levels of usual physical activity (0.54, 95% CI 0.34 to 0.86), and taking anticholinergic drugs (1.81, 95% 1.11 to 2.94). Exposure to passive smoking was also related to an increased risk of readmission with COPD after adjustment for clinical factors (1.63, 95% CI 1.04 to 2.57) but did not remain in the final model. CONCLUSIONS: This is the first study to show a strong association between usual physical activity and reduced risk of readmission to hospital with COPD, which is potentially relevant for rehabilitation and other therapeutic strategies.

Aged↗
PubMed2003

[Angioplasty and stenting in severe stenosis of basilar artery refractory to pharmacotherapy].

Stenoses in the posterior cerebral circulation often have a bad prognosis. There may be a high rate of morbi-mortality and recurrences of ischemic events in this territory. Currently we have no evidence or consensus about what the best pharmacological option is for these patients. We report a case of a 75 year old woman with sever stenosis of the proximal part of the basilar artery with recurrent transient ischemic events unresponsive to different combinations of antiagregant and anticoagulant treatments. A percutaneous transluminal angioplasty with the addition of a stent in the basilar artery was performed successfully. At present, there are few studies and a low number of patients treated by this technique. The results obtained are promising, with a low rate of morbi-mortality, the most frequent complications being embolization of the atherosclerotic lesion, dissection, rupture or restenosis.

Aged↗
PubMed2000

[Warthin tumor. Report of eight cases and review of the literature].

We have studied 8 patients with Warthin's tumor of the parotid gland (WT). Seven of them were men and smoked more than a packet daily. Seven were operated with conservative superficial parotidectomy and the other one with total parotidectomy with facial preservation. Two had postoperative peripheral facial paresia which disappeared with medical treatment in few days. One of the operated suffered from postoperative Frey's syndrome.

Adenolymphoma↗
PubMed2000

[Our management protocol and surgical technique in cerebrospinal fluid rhinorrhea treated with an endonasal approach].

Five patients with cerebrospinal fluid fistula (CFF) have been treated with intratecal fluoresceine, 2 cc at 2%, and endoscopic nasal surgery. In 3 patients CFF was postraumatic; one case spontaneous and another case iatrogenic. In all the cases CFF have been solved in the first time. Postoperatory follow-up vary from 8 to 14 months, and no recurrence was observed. Fluorescein must be managed adequately for prevent neural complications.

Adult↗
PubMed1999

[Benign metastasizing pulmonary leiomyomatosis. A report of 3 cases].

The benign metastasizing leiomyoma is an uncommon variety of leiomyoma, tumor derived from smooth muscular tissue. The benign metastasizing leiomyoma affects a middle age women, with antecedents of uterine leiomyoma, the pulmonary lesions appeared as a multiple nodules, without systemic affectation. We present three cases of benign metastasizing leiomyoma that de diagnosis was made for biopsy by thoracotomy; and in one case the markers from estrogens' receivers were positive.

Biopsy↗
PubMed1999

Analysis of tracheal sounds during forced exhalation in asthma patients and normal subjects: bronchodilator response effect.

PURPOSE: During the past 10 years, the acoustic analysis of breath sounds has been used as a diagnostic tool in patients suffering from obstructive respiratory diseases. Acoustic analysis might be able to monitor the response to bronchodilator therapy in a clinical setting. So far, few studies have been carried out in asthmatic patients. To assess the responses of a sampling of asthma patients to an inhaled bronchodilator (terbutaline) by means of spectral analysis of the tracheal sound performed during forced expiratory maneuvers. MATERIAL AND METHODS: Seventeen nonsmoking asthma patients (9 were male, 8 were female) who had been suffering from the disease for > or = 15 years were included in the study, as were 15 normal subjects (7 were male, 8 were female). The average age (+/- SD) was 56.5 +/- 15.2 years (FVC, 2.7 +/- 0.9 L [63.4%]; FEV1, 1.5 +/- 0.6 L [53.0%]). The tracheal sounds were collected during three forced expiratory maneuvers with a sampling frequency of 5,000 Hz and were analyzed by applying a 16-parameter autoregressive model. RESULTS: The centroid frequency decreased after the bronchodilator was given at different flow segments between 1.2 and 0.4 L/s, with significant changes between 0.6 and 0.4 L/s. CONCLUSIONS: Patients with asthma showed changes in the spectral acoustic analysis frequencies after the administration of a bronchodilator drug (terbutaline) during forced expiratory maneuvers.

Adolescent↗
PubMed1999

Evaluation of institutional cancer registries in Colombia.

The four primary objectives of this descriptive study were to: 1) design a quality-measurement instrument for institutional cancer registries (ICRs), 2) evaluate the existing ICRs in Colombia with the designed instrument, 3) categorize the different registries according to their quality and prioritize efforts that will efficiently promote better registries with the limited resources available, and 4) determine the institution with the greatest likelihood of successfully establishing Colombia's second population-based cancer registry. In 1990 the National Cancer Institute of Colombia developed 13 institution-based cancer registries in different Colombian cities in order to promote the collection of data from a large group of cancer diagnostic and treatment centers. During the first half of 1997, this evaluation reviewed 12 registries; one of the original 13 no longer existed. All of the Colombian institutions (hospitals) that maintain institution-based cancer registries were included in the study. At each institution, a brief survey was administered to the hospital director, the registry coordinator, and the registrar (data manager). Researchers investigated the institutions by looking at six domains that are in standard use internationally. Within each domain, questions were developed and selected through the Delphi method. Each domain and each question were assigned weights through a consensus process. In most cases, two interviewers went to each site to collect the information. The university hospitals in Cali, Pereira, and Medellín had substantially higher scores, reflecting a good level of performance. Four of the 12 institutions had almost no cancer registry work going on. Five of the 12 hospital directors considered that the information provided by the cancer registries influenced their administrative decisions. Three of the registries had patient survival data. Four of the institutions allocated specific resources to operate their cancer registries; in the other 8 hospitals there was no clear budget allocation. Seven of the hospital directors could not identify five or more objectives of a cancer registry. Data management was usually poor and resources insufficient at most of the institutions. In summary, the cancer registry system in Colombia varies greatly from institution to institution. A few of the hospitals do a good job while others have neglected the registries. The high, identical total scores for Pereira and Medellín suggest they would be good locations to establish new population-based cancer registries similar to the existing one in Cali. However, the overall characteristics in Pereira may provide a more appropriate environment for the second registry, with Medellín as an alternative.

Colombia↗
PubMed1998

nCPAP treatment interruption in OSA patients.

This study has investigated the effect of interrupting nasal continuous positive airway pressure (nCPAP) therapy on 10 obstructive sleep apnoea (OSA) patients (nine male, one female) (53.6 +/- 7.3 years) treated over 2 years. The effect of nCPAP interruption was determined by variations in sleep counts and gasometric values during five consecutive nights. On the first night, the patient used his habitual nCPAP. On the remaining nights, nasal nCPAP was not applied. The apnoea-hypopnoea index (AHI) was found to increase significantly in the second night, attaining a similar level to that of the basal study (2 years ago). SaO2 minimum decreased and PaCO2 increased in the second night with respect to the first night. The interruption of nCPAP therapy in OSA patients treated over a long period of time increases the sleep counts and impairs the gasometric parameters. Consequently, any change in nCPAP time therapy must be checked to avoid negative effects.

Carbon Dioxide↗
PubMed1998

Quality of life in severe chronic obstructive pulmonary disease: correlation with lung and muscle function.

UNLABELLED: Chronic obstructive pulmonary disease (COPD) patients suffer from significant impairment in quality of life (QL), but the variables related to this impairment are not well known. The aim of this study has been to identify physiological parameters related to QL in severe COPD patients undergoing long-term oxygen therapy. MATERIALS AND METHODS: We studied 47 COPD patients using long-term oxygen therapy (43 men/four women, 65.17 SD 8.21 years, 3.17 SD 2.61 years on oxygen). The Nottingham Health Profile (NHP) and activities of daily living (ADL) questionnaire were used to measure QL. Subjective assessment of dyspnoea was performed using a visual analogue scale. The physiological parameters determined were lung function (spirometry, arterial blood gases, lung volumes and carbon monoxide diffusing capacity), muscle function (maximum inspiratory and expiratory pressures, deltoid muscle and handgrip strength), and nutrition status (tricipital skin fold and mid-arm muscle circumference). RESULTS: High ADL (8.32 SD 6.97) and NHP scores (energy 63.3 SD 40.43, pain 35.11 SD 31.56, emotional reactions 43.03 SD 25.13, sleep 51.91 SD 32.75, social isolation 30.64 SD 26.98, physical mobility 49.73 SD 24.93) demonstrated clinically significant QL impairment in the severe COPD patients studied. Stepwise multiple regression analysis found a correlation between lung function and QL. Low FEV1% was associated with impairment in energy, physical mobility and social isolation NHP scores and ADL score (r = -0.3, P < 0.05). RV/TLC also correlated with ADL and social isolation scores (r = 0.3, P < 0.05). Lung function explained 39-45% of the variation in these QL dimensions. QL did not correlate with other lung function parameters, muscle function or nutrition status. CONCLUSION: COPD patients using long-term oxygen suffer from severe QL impairment affecting not only energy and mobility but also emotional reactions, social isolation and sleep. Lung function is related to energy, mobility and social isolation dimensions, but muscle function is unrelated to QL in these patients.

Aged↗
PubMed1998

Postanitbiotic and sub-MIC effects of azithromycin and isepamicin against Staphylococcus aureus and Escherichia coli.

Investigations of pharmacodynamic parameters (postantibiotic effect [PAE], sub-MIC effects [SMEs], etc.) have been progressively employed for the design of dosing schedules of antimicrobial agents. However, there are fewer in vivo than in vitro data, probably because of the simplicity of the in vitro procedures. In this study, we have investigated the in vitro PAE, SME, and previously treated (postantibiotic [PA]) SME (1/2 MIC, 1/4 MIC and 1/8 MIC) of azithromycin and isepamicin against standard strains of Staphylococcus aureus and Escherichia coli by using centrifugation to remove the antibiotics. In addition, the in vivo PAE and SME have been studied with the thigh infection model in neutropenic mice. Finally, in vivo killing curves with two dosing schedules were determined to examine whether the PAE can cover the time that antimicrobial agents are below the MIC. The two antimicrobial agents induced moderate-to-high in vitro PAEs, SMEs, and PA SMEs against S. aureus (>8 h) and E. coli (3.38 to >7.64 h). The in vivo PAEs were also high (from 3.0 to 3.6 h), despite the fact that isepamicin had lower times above the MIC in serum. Only azithromycin showed a high in vivo SME against the two strains (1.22 and 1.75 h), which indicated that the in vivo PAEs were possibly overestimated. In the killing kinetics, no great differences (<0.5 log10) were observed between the schedule that took the PAE into account and the continuous administration of doses. These results are comparable with those of other authors and suggest that these antimicrobial agents could be administered at longer intervals without losing effectiveness.

Animals↗
PubMed1998

Indices of respiratory muscle endurance in healthy subjects.

BACKGROUND: The evaluation of respiratory muscle performance can be described in terms of strength and endurance, the latter usually being measured by means of resistive or threshold inspiratory loads, using devices that are also used for respiratory muscle training. Few authors, however, have published endurance reference values for healthy subjects. To that end, we studied two indices of respiratory muscle endurance in a population of 99 healthy volunteers (50 men, 49 women) divided into five age groups (20-70 years old) applying a modification of the methods of Martyn et al. and Nickerson and Keens. Inspiratory muscle endurance (Tlim) was defined as the time the subject was able to sustain breathing against an inspiratory pressure load equivalent to 80% of the maximum tolerated load (Cmax). Cmax was calculated using a 2-min incremental threshold load. RESULTS: We found that the heaviest inspiratory threshold load tolerated for 2 min and the time a load equivalent to 80% of Cmax (Tlim) could be sustained were not significantly different for male and female subjects. Tlim correlated with Cmax, age, height, and maximum respiratory pressures.

Adult↗
PubMed1996

Evaluation of the use of three different devices for nocturnal oxygen therapy in COPD patients.

OBJECTIVE: To determine whether transtracheal catheter and reservoir nasal cannula contribute to maintaining adequate oxygen saturation during sleep, and to calculate the oxygen saving they allow compared to nasal prongs. DESIGN: A prospective study in which patients were randomly assigned to either nasal prongs or oxymizer device prior to transtracheal oxygen delivery. Arterial oxygen saturation was then monitored by a finger pulse oximeter during 8 h of sleep. SETTING: Pulmonary ward of 'The Hospital Universitari Germans Trias i Pujol, Badalona (Barcelona/Spain)'. PATIENTS: Fourteen stable hypoxemic (PaO2 50 +/- 6.9 mm Hg; PaCO2 51.5 +/- 9.3 mm Hg) COPD patients (FVC 44 +/- 19%; FEV1 26.5 +/- 11.5%; FEV1/FVC 44.9 +/- 9.7%) already receiving oxygen therapy at home. MEASUREMENTS: Pulmonary function test was performed. The lowest flow required to obtain an SaO2 at or above 88% for over 95% of the sleep time was determined for each type of oxygen delivery. Patients were not switched to the next type of oxygen delivery device until 3 reliable pulse oximetries had been obtained. The percentage of oxygen savings was calculated. Awake PaO2 was measured in patients using nasal prongs and transtracheal catheter while continuing to inspire oxygen at the same flow rate as when asleep. RESULTS: As expected, no differences were found in SaO2 measurements for the three types of oxygen delivery. Oxygen savings were 48.65% for the oxymizer device and 52.87% for the transtracheal catheter. Awake PaO2 was significantly higher (p < 0.04) in patients with nasal prongs than in those with transtracheal catheter at the flow rate required when asleep. CONCLUSIONS: The oxymizer device and transtracheal oxygen delivery benefit hypoxemic COPD patients reducing oxygen use during sleep by around 50%. Higher PaO2 levels were necessary to prevent nocturnal SaO2 decreases in patients with nasal prongs than in patients with transtracheal oxygen delivery. Oxygen-conserving devices are reliable and advisable methods for nocturnal oxygenation.

Aged↗
PubMed1996

The role of induction (neoadjuvant) chemotherapy in stage IIIA NSCLC.

Induction (neoadjuvant) chemotherapy has become an accepted treatment for stage IIIA (T1-3N2M0) non-small cell lung cancer. In two recent randomized trials, neoadjuvant chemotherapy plus surgery gave an increase in median survival at least fivefold greater than surgery alone. The Spanish Lung Cancer Group trial of preoperative chemotherapy, in which the cisplatin dose was randomized to either 50 mg/m2 or 100 mg/m2 plus 3 g/m2 ifosfamide and 6 mg/m2 mitomycin, examines the effect of K-ras gene mutations on tumor response and survival. Patients whose tumors contain K-ras gene mutations are more likely to develop distant metastases and have lower median survival than patients without such mutations. Microsatellite instability seems to be a frequent mechanism of genetic aberrations. Knowledge about these genetic alterations could have prognostic importance and may identify the patients who should receive the most aggressive additional treatment.

Carcinoma, Non-Small-Cell Lung↗
PubMed1996

[Factors associated with pleural thickening in pleural tuberculosis. Review of 99 cases].

OBJECTIVE: To analyze which factors were related to the development of pleural thickening in pleural tuberculosis (PT). METHODS: We reported 99 patients diagnosed as having PT separated into two different groups according to the presence of radiographic pleural thickening after completing the treatment: normal chest roentgenogram (group 1) or pleural thickening (group 2). We compared: clinical history, chest radiography, pleural fluid analysis, microbiological studies and effects of the treatment. RESULTS: 35 cases in group 1 (35.35%) and 64 in group 2 (64.45%). All the compared results did not differ between the two groups, excluding a higher incidence of febrile cases, increased white cell count and decreased relative percentage of pleural lymphocytes in group 1, and increased number of cases with hemoptysis, positive sputum cultures in patients with parenchymal infiltrates, relative percentage of pleural lymphocytes and decreased white cell count in group 2. CONCLUSIONS: We reported an elevated incidence of residual pleural thickening, but it is unlikely that all the cases could have any clinical significance. We didn't confirm a characteristic pattern. Our findings suggested that a different reaction related or not to the hypersensitivity, rather than the inflammatory response to infection was the responsible for the fibrosis.

Adolescent↗
PubMed1995

[Transtracheal catheter and liquid oxygen: 5 years of experience].

We studied clinical tolerance, complications, change in pulmonary function test results, arterial gasometrics, hemoglobin (Hb), 6 minute stress tests (6 wt) and subjective perception of dyspnea assessed on a visual analog scale (VAS) in a group of 18 patients (17 with obstructive disease and one with restrictive disease). These patients had previously been enrolled in a home oxygen therapy (HOT) program to deliver continuous oxygen therapy through nasal prongs, and had accepted portable oxygen therapy delivered by transtracheal catheter (TTC) from 1988 until 1993. Tolerance was good, there were no lethal complications of TTC, and excellent compliance with the prescribed HOT was achieved. Lung function test results worsened, while Hb and PaO2 improved and significant oxygen savings (50%) were achieved. The 6 wt test results had not worsened at the end of the first year but did so significantly at the end of the third year, in spite of a relative preservation of lung function. Dyspnea assessed on a VAS was not seen to worsen. We conclude that tolerance of the method was good and that no relevant complications occurred. HOT by TTC did not prevent worsening of bronchial obstruction. Oxygenation of patients was better, as shown by the decrease in Hb and the improvement in PaO2 at the end of the first year of monitoring. Changes in 6 wt showed that in order to achieve greater benefit from HOT by TTC, patients should follow a pulmonary rehabilitation program.

Aged↗