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J Roca

Publications and source records attributed to J Roca.

At least 19 recordsLinked to original sources
PubMed1992

The capture of a DNA double helix by an ATP-dependent protein clamp: a key step in DNA transport by type II DNA topoisomerases.

The binding of linear and circular forms of DNA to yeast DNA topoisomerase II or its complex with AMPPNP, the nonhydrolyzable beta,gamma-imido analog of ATP, was carried out to probe the ATP analog-induced conformational change of the enzyme. Binding of the ATP analog is shown to convert the enzyme to a circular clamp with an annulet, through which only a linear DNA can pass; subsequent circularization of the bound linear DNA forms a salt-stable catenane between the protein circular clamp and the DNA ring. Analysis of catenane formation between a small DNA ring originally bound to the topoisomerase and a large DNA ring subsequently added, under conditions such that the two do not exchange, supports a model in which a second DNA double-helix can enter the open jaws of a DNA-bound protein clamp, and the closure of the jaws upon ATP-binding traps the second duplex and transports it through an enzyme-operated gate in the first DNA duplex.

Adenosine Triphosphatases↗
PubMed1992

[Cardiac tamponade: clinical review of 53 cases].

BACKGROUND: To describe the clinical features and prognosis of the patients with cardiac tamponade admitted in the coronary care unit. METHODS: Analysis the clinical data, etiology, treatment, and short term outcome of fifty three patients presenting with cardiac tamponade that required pericardiocentesis. RESULTS: Neoplasm (21 cases) and idiopathic pericarditis (10 cases) were the most frequent causes of cardiac tamponade. In forty four patients an haemorrhagic fluid was obtained. Neoplastic pericardial fluid showed a higher haematocrit than the rest (18 +/- 8% vs 7 +/- 5%, p less than 0.01). Recurrence of tamponade occurred in all but one neoplastic patients, and was early (less than 48 h) in 18 patients. Twenty seven patients underwent pericardiectomy, and recurrence was the most frequent indication (18 cases). Overall in-hospital mortality was 26%. Ten out of 14 deaths occurred in neoplastic patients and 2 deaths after myocardial perforation related to temporary pacemaker. No patient with idiopathic or post-pericardiotomy cardiac tamponade died. CONCLUSIONS: Short term outcome and prognosis in patients with cardiac tamponade mainly depends on the etiology. A high rate of early recurrence and death characterize the malignant cardiac tamponades.

Adult↗
PubMed1992

The hepatopulmonary syndrome: new name, old complexities.

On the basis of previous work, our own experience and findings, and the considerations discussed above, we propose a set of four diagnostic criteria for the hepatopulmonary syndrome: 1. presence of chronic hepatic disease (alcoholic, postnecrotic, or primary biliary cirrhosis or active chronic hepatitis)--severe liver dysfunction may not be mandatory; 2. absence of intrinsic cardiopulmonary disease, with normal chest radiograph or with nodular basal shadowing; 3. pulmonary gas exchange abnormalities--an increased alveolar-arterial oxygen gradient (> or = 2.0 kPa) with or without hypoxaemia; 4. the extrapulmonary appearance of intravenous radiolabelled microspheres or a positive contrast enhanced echocardiogram, suggesting intrapulmonary vascular abnormalities. Although these four criteria appear straightforward, there may be other features that are not always present--namely: 1. low transfer factor (diffusing capacity); 2. shortness of breath, with or without platypnoea and orthodeoxia; 3. increased cardiac output and reduced pulmonary vascular pressures; 4. small (or no) increase in pulmonary vascular resistance when the patient is breathing low oxygen mixtures. From the physiological viewpoint, the hepatopulmonary syndrome provides an excellent model for clinical research in the pathophysiology of pulmonary gas exchange. So far it has been possible to show that arterial hypoxaemia in this condition is (1) partitioned into components resulting from VA/Q mismatching, intrapulmonary shunt, and limitations of oxygen diffusion; (2) modulated by the interplay between the intrapulmonary and the extrapulmonary determinants of PaO2, such as cardiac output and minute ventilation; (3) vulnerable to the influence of inadequate pulmonary vascular tone; and (4) resolved when the injured liver is replaced and hepatic function is restored to within normal limits.

Arteriovenous Anastomosis↗
PubMed1992

Interstitial pulmonary fibrosis with and without associated collagen vascular disease: results of a two year follow up.

BACKGROUND: Interstitial pulmonary fibrosis is a disease with a highly variable clinical course. To ascertain if an inadequate selection of patients might explain part of this variability, two different groups of patients with interstitial pulmonary fibrosis, those with the "lone" form of the disease (LIPF) and those with associated collagen vascular disorders (AIPF), were studied separately. METHODS: Twenty consecutive patients (nine with LIPF and 11 with AIPF) were included. Their clinical and radiographic findings and results of pulmonary function tests, gallium-67 lung scanning, and cellular analysis of bronchoalveolar lavage fluid were compared at diagnosis. Moreover, the evolution of LIPF and AIPF was contrasted after a follow up of two years, both groups having received a similar treatment regimen of corticosteroids. RESULTS: At enrollment, patients with LIPF and AIPF were of similar age, and had similar symptoms and derangement of lung function, but patients with LIPF presented with finger clubbing, more obvious radiographic abnormalities, and a greater percentage of eosinophils in bronchoalveolar lavage fluid. Two years later, patients with LIPF had significantly decreased FVC, FEV1, TLC, TLCO, and PaO2. By contrast, lung function remained unaltered in patients with AIPF. Similarly, when the percentage change from entry to the study was compared, patients with LIPF showed a significant decrease in FVC, FEV1, and PaO2. CONCLUSIONS: Unlike the patients with AIPF, those with LIPF showed a deterioration in lung function and developed further restrictive impairment and poorer gas exchange. This has implications in their clinical management.

Adult↗
PubMed1992

Pulmonary complications after long term amiodarone treatment.

BACKGROUND: Amiodarone hydrochloride is an antiarrhythmic agent useful in arrhythmias refractory to standard therapy. Although interstitial pneumonitis is known to be its most serious side effect, several aspects of amiodarone lung toxicity are still controversial. METHODS: Pulmonary side effects were examined in a sample of 61 symptomless patients (mean (SD) age 55 (7) years) who had had long term treatment with amiodarone (daily maintenance dose 400 mg), selected from 482 men attending the University of Barcelona myocardial infarction project. To allow for the confounding effects of coronary artery disease and tobacco history on lung function, 46 patients who had taken amiodarone for more than one year were matched with a control group from the same population. Subjects underwent measurement of lung volumes, arterial blood gas analysis and an incremental bicycle exercise test. RESULTS: Most lung function values were close to predicted values, though there was a small increase in resting alveolar-arterial oxygen tension difference (A-aDO2) at rest (4.8 (1.4) kPa in both groups). There were no differences in the results of forced spirometry or static lung volumes between the two groups, or in the fall in A-aDO2 from rest to exercise. There was a small difference between the amiodarone and the control group in transfer factor for carbon monoxide corrected for lung volume (KCO 1.67 (0.3) and 1.83 (0.3) mmol min-1 kPa-1 l-1 respectively) and in exercise capacity (140 (25) and 120 (30)w). Only three patients showed lung function impairment consistent with pneumonitis. No relation between lung function measures and cumulative doses of amiodarone or desethylamiodarone was found. CONCLUSIONS: The prevalence of clinically evident pulmonary side effects was 4.9%, which is lower than that reported in studies in which higher daily maintenance doses of amiodarone were given. The slightly lower KCO values and lower work load achieved by the patients taking amiodarone suggest a small effect of amiodarone in doses of 400 mg on lung function. A role for individual susceptibility to pulmonary complications of amiodarone treatment is suggested.

Amiodarone↗
PubMed1992

Effects of training on muscle O2 transport at VO2max.

To quantify the relative contributions of convective and peripheral diffusive components of O2 transport to the increase in leg O2 uptake (VO2leg) at maximum O2 uptake (VO2max) after 9 wk of endurance training, 12 sedentary subjects (age 21.8 +/- 3.4 yr, VO2max 36.9 +/- 5.9 ml.min-1.kg-1) were studied. VO2max, leg blood flow (Qleg), and arterial and femoral venous PO2, and thus VO2leg, were measured while the subjects breathed room air, 15% O2, and 12% O2. The sequence of the three inspirates was balanced. After training, VO2max and VO2leg increased at each inspired O2 concentration [FIO2; mean over the 3 FIO2 values 25.2 +/- 17.8 and 36.5 +/- 33% (SD), respectively]. Before training, VO2leg and mean capillary PO2 were linearly related through the origin during hypoxia but not during room air breathing, suggesting that, at 21% O2, VO2max was not limited by O2 supply. After training, VO2leg and mean capillary PO2 at each FIO2 fell along a straight line with zero intercept, just as in athletes (Roca et al. J. Appl. Physiol. 67: 291-299, 1989). Calculated muscle O2 diffusing capacity (DO2) rose 34% while Qleg increased 19%. The relatively greater rise in DO2 increased the DO2/Qleg, which led to 9.9% greater O2 extraction. By numerical analysis, the increase in Qleg alone (constant DO2) would have raised VO2leg by 35 ml/min (mean), but that of DO2 (constant Qleg) would have increased VO2leg by 85 ml/min, more than twice as much. The sum of these individual effects (120 ml/min) was less (P = 0.013) than the observed rise of 164 ml/min (mean). This synergism (explained by the increase in DO2/Qleg) seems to be an important contribution to increases in VO2max with training.

Adaptation, Physiological↗
PubMed1992

Risk factors of soybean epidemic asthma. The role of smoking and atopy.

Epidemics of emergency room admissions for asthma occurring in Barcelona during the period 1981 to 1987 were caused by inhalation of soybean dust. To investigate the risk factors that determined why some asthma patients became reactive to soybean and were consequently affected by the asthma epidemics of Barcelona but others did not do so, a case-control study was conducted during 1989, 2 yr after the cessation of asthma epidemics. Patients with asthma admitted in emergency room services during epidemic asthma days (n = 169) were compared with asthma patients admitted in the same services during nonepidemic days and who were never admitted during the epidemics (n = 147). Risk factors other than soybean exposure, namely skin reactivity against at least one common allergen (odds ratio [OR] 3.0, 1.7 to 5.3), age over 64 yr (OR 2.8, 1.4 to 6.0), cigarette smoking at the time of the epidemics (OR 2.3, 1.2 to 2.4), past smoking (OR 1.8, 0.9 to 3.7), and total immunoglobulin E (IgE) higher than 100 IU/ml (OR 1.7, 1.0 to 3.0), were found independently related to epidemic asthma. The role of smoking was especially important for those who had a positive skin reaction and were exposed to soybean dust (OR 7.9, 1.8 to 36.0). In this group, a dose-response pattern with pack-years was observed (p less than 0.01). The present findings suggest a multifactorial process for epidemic asthma, in which atopy and cigarette smoking played an important synergistic role. This has a preventive potential for IgE-related asthma.

Asthma↗
PubMed1992

Effect of intravenously administered aminophylline on ventilation/perfusion inequality during recovery from exacerbations of chronic obstructive pulmonary disease.

To investigate the effect of intravenously administered aminophylline and 100% O2 breathing on ventilation-perfusion (VA/Q) inequality, nine patients recovering from an acute exacerbation of chronic obstructive pulmonary disease (COPD) were studied. The design was double-blind, crossover, placebo-controlled for aminophylline, and a single-blind, controlled protocol for O2, patients being studied on two successive days. Forced spirometry, systemic hemodynamics, arterial pH, and blood gases were measured together with the VA/Q distribution using the multiple inert gas elimination technique, and then a loading dose of aminophylline (6 mg/kg body weight) or placebo was given over 20 min followed by a maintenance infusion at 0.9 mg/kg/h that was kept constant for the rest of the study. After 20 min of infusion the patient breathed either air or 100% O2 for another 30 min, and the measurements were repeated. Thereafter the inspired gas was shifted to the other FlO2 for 30 min, and a final set of measurements was made. The following day the procedure was repeated using the alternate drug. Aminophylline alone increased FVC and FEV1, but it produced no change in the group in ventilation, hemodynamics, blood gases, or the VA/Q distribution, although individual patients who had low VA/Q areas at baseline showed increases in these areas and worsening of log SD Q. Oxygen alone reduced cardiac output (QT) and caused modest further dispersion of the VA/Q distribution when compared with air breathing during placebo infusion (log SD Q 1.03 +/- 0.27 increased to 1.26 +/- 0.35, p less than 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Deep venous thrombosis and the risk of pulmonary embolism. A systematic study.

The influence of several diseases and clinical conditions on the presence of pulmonary embolism (PE) in a large series of patients with deep venous thrombosis (DVT) in the lower extremities was analyzed prospectively. Lung scan findings from a series of 434 consecutive patients with DVT (with and without symptoms of PE) were studied and then correlated to five clinical variables: age, sex, elapsed time since clinical symptoms had appeared in the leg to diagnosis, degree of proximity of venous thrombus, and the presence or not of several risk factors that could have predisposed to thrombus development. According to scintigraphic findings, 164 patients were considered to have PE (asymptomatic in 76 of them), while 200 patients were classified as having only DVT. Lung scan was considered to be indeterminate for PE in 70 patients, and they were not included in the study. No differences were found in terms of age, sex, interval of time elapsed since onset of symptoms to diagnosis, or in the degree of proximity of the thrombus. However, several differences between groups were found when comparing the presence or absence of several predisposing factors for thrombosis: DVT developing in immobilized patients was associated with a significantly lower incidence of PE as compared with nonimmobilized patients (p = 0.005). Conversely, patients with a history of venous thromboembolism (VTE) had a significantly higher rate of embolism (31/51 vs 133/313; p = 0.01). On logistic regression analysis, a history of VTE showed a statistically significant association with more than a twofold higher risk of having PE for patients with such an antecedent. Our findings suggest that different pathophysiologic pathways could perhaps explain differences in embolic potential.

Causality↗
PubMed1992

[Meningitis in pediatrics. Clinical and epidemiological study of 173 cases].

BACKGROUND: To know the incidence, clinical presentation, differential diagnosis and resistance level to antibiotics in pediatric meningitis. METHODS: 173 cases of meningitis (bacterial: 69, viral: 104) have been prospectively followed during 1988 according to a previously established clinical and laboratory protocol. RESULTS: Meningitis attack rate was 60 cases/100,000 children younger than 15 years per year (meningococcal: 25/100,000, Haemophilus: 2/100,000). Mortality was 1.4%. 40% of bacterial meningitis received previous antibiotic treatment. Sensitivity of culture, Gram stain, and direct antigen detection by latex and EIA was 79%, 61.7%, 20.5% and 34%, respectively. Bacterial and viral differential diagnosis, by the application of Boyer's score was 95% sensitive and 98% specific. Four out of six cases of Haemophilus meningitis were ampicillin and chloramphenicol resistant; 39% of meningococcus had their penicillin susceptibility decreased between 2 and 8 times, although no therapeutic failures were seen. CONCLUSIONS: Laboratory parameters might not separate bacterial and viral meningitis at early stages of illness. Gram stain is an excellent and sensitive method of bacterial detection in CSF. Moderate resistance to penicillin in meningococcus is very frequent but clinical failures are not yet present.

Adolescent↗
PubMed1991

Mechanisms of abnormal gas exchange in patients with pneumonia.

The mechanisms of abnormal gas exchange in patients with pneumonia and the gas exchange response while breathing high inspired O2 concentrations have not been clearly elucidated. To this end, we studied 23 inpatients with pneumonia and mild to severe arterial hypoxemia and/or increased alveolar - arterial O2 difference. Ventilation-perfusion (VA/Q) distributions were obtained upon breathing room air (or maintenance inspired oxygen fraction) and 100% O2 in random order. Subjects were divided in two groups according to whether they were spontaneously breathing (SB, n = 13) or their lungs were mechanically ventilated (MV) because of acute severe respiratory failure (n = 10). The SB patients showed only small amounts of shunt (7 +/- 2%) (mean +/- standard error) and moderate VA/Q mismatching, characterized by the presence of a small percentage of blood flow to low VA/Q units (VA/Q less than 0.1) (4 +/- 1%). In contrast, patients whose lungs were MV had larger shunts (22 +/- 5%) and greater percent of perfusion to low VA/Q units (11 +/- 5%). While breathing 100% O2, shunt remained unchanged but the dispersion of the pulmonary blood flow distribution (log SDQ) (normal range, 0.3-0.6) increased in each group (from 1.04 +/- 0.10 to 1.29 +/- 0.13 in SB and from 1.40 +/- 0.11 to 1.64 +/- 0.14 in MV; P less than 0.05 each), suggesting release of hypoxic pulmonary vasoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Mechanisms of gas-exchange impairment in idiopathic pulmonary fibrosis.

To investigate the mechanisms of pulmonary gas-exchange impairment in idiopathic pulmonary fibrosis (IPF) and to evaluate their potential relationship to the CO diffusing capacity (DLCO), we studied 15 patients with IPF (mean DLCO, 52% of predicted) at rest (breathing room air and pure O2) and during exercise. We measured pulmonary hemodynamics and respiratory gas-exchange variables, and we separated the ventilation-perfusion (VAQ) mismatching and O2 diffusion limitation components of arterial hypoxemia using the multiple inert gas elimination technique. At rest VA/Q mismatching was moderate (2 to 4% of cardiac output perfusing poorly or unventilated lung units), and 19% of AaPO2 was due to O2 diffusion limitation. During exercise VA/Q mismatch did not worsen but the diffusion component of arterial hypoxemia increased markedly (40% AaPO2, p less than 0.005). We observed that those patients with higher pulmonary vascular tone (more release of hypoxic pulmonary vasoconstriction) showed less pulmonary hypertension during exercise (p less than 0.05), less VA/Q mismatching [at rest (p less than 0.005) and during exercise (p less than 0.0025)], and higher arterial PO2 during exercise (p = 0.01). We also found that DLCO corrected for alveolar volume (KCO) correlated with the mechanisms of hypoxemia during exercise [VA/Q mismatching (p less than 0.025) and O2 diffusion limitation (p less than 0.05)] and with the increase in pulmonary vascular resistance elicited by exercise (p less than 0.005). In conclusion, we showed that the abnormalities of the pulmonary vasculature are key to modulate gas exchange in IPF, especially during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Ventilation-perfusion mismatch after methacholine challenge in patients with mild bronchial asthma.

To investigate the effects of methacholine (MTH) challenge on spirometry, lung mechanics, respiratory gases, and ventilation-perfusion (VA/Q) distributions, 16 subjects 16 to 58 yr of age with stable mild asthma (FEV1, 92 +/- 5% [SEM] predicted; FEF25-75, 71 +/- 7% predicted; respiratory system resistance (Rrs) at 4 Hz, 4.6 +/- 0.4 cm H2O/L-1 s; PaO2, 88 +/- 3 mm Hg; AaPO2, 23 +/- 3 mm Hg) were recruited. Baseline VA/Q distributions were unimodal and relatively narrow in 12 patients and modestly bimodal in the other four. The dispersion of pulmonary blood flow (log SD Q) was slightly enlarged (0.71 +/- 0.09) and that of ventilation (log SD V) was normal (0.57 +/- 0.04) (normal range, 0.3 to 0.6); an index of overall VA/Q heterogeneity (DISP R-E*) was also mildly abnormal (5.3 +/- 0.8) (normal values less than 3.0). After MTH challenge, FEV1, FEF25-75, and PaO2 fell (to 62 +/- 3 and 35 +/- 3% predicted, and to 71 +/- 1 mm Hg, respectively), whereas Rrs (p less than 0.001 each), minute ventilation (p less than 0.02), heart rate (p less than 0.01), and AaPO2 increased (p less than 0.001). VA/Q relationships mildly to moderately worsened (log SD Q increased to 0.98 +/- 0.04 [p less than 0.01], log SD V to 0.79 +/- 0.04, and DISP R-E* to 9.8 +/- 0.6 [p less than 0.001 each]). Qualitatively, the pattern of blood flow distribution was broadly unimodal in 13 patients and modestly bimodal in three, of whom only one had a bimodal baseline distribution.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Gas exchange during exercise in mild chronic obstructive pulmonary disease. Correlation with lung structure.

To investigate whether or not the pathologic features in the lungs of patients with chronic obstructive pulmonary disease (COPD) are related to the gas exchange response during exercise, we studied 17 patients (15 men, two women) with mild-to-moderate airflow obstruction (FEV1/FVC ratio, 59 +/- 3%), undergoing resective lung surgery, at rest and during submaximal exercise (71 +/- 5% predicted VO2max). During exercise, arterial PO2 increased (from 81 +/- 3 to 86 +/- 3 mm Hg, p less than 0.05) as a result of an overall improvement in VA/Q relationships. This improvement included an increase in the mean VA/Q ratios of both ventilation and blood flow distributions, and a more homogeneous ventilation distribution (logSD V, from 0.66 +/- 0.06 to 0.50 +/- 0.03; p less than 0.01; normal value, less than or equal to 0.6). The morphologic evaluation of the resected specimens disclosed a moderate degree of emphysema (emphysema score, 16 +/- 4) and mild abnormalities in membranous bronchioles (total pathology score, 107 +/- 8). At rest, significant correlations were found between the severity of the pathologic findings and both the degree of hypoxemia and the extent of VA/Q mismatching. During exercise, no relationship between bronchiolar abnormalities and gas exchange measurements was observed, whereas the severity of emphysema was correlated with PaO2 (r = -0.54, p less than 0.05). Both the overall increase in and the more efficient distribution of ventilation accounted for the improvement in VA/Q distributions during exercise. These changes were more pronounced in patients with a greater degree of bronchiolar abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[An elevated prevalence of subclinical pulmonary involvement in systemic lupus erythematosus].

Lung function was prospectively studied in a group of non-selected systemic lupus erythematosus (SLE) female patients who consecutively came to our Lung Function Laboratory. There was no previous history of smoking in any patient nor there was clinical and/or radiographic evidence of lung affectation prior to the diagnosis of SLE. Some respiratory lung function abnormalities were observed in 17 patients (65%). The most frequent functional anomaly was the alteration in carbon monoxide transfer (DLCO), which was present in 10 cases (38%). On the other hand, a restrictive ventilatory failure was observed in 8 patients (31%) and a obstructive ventilatory failure in 6 other (23%). Out of these, 3 patients (12% of the total number of cases) presented bronchial hyperreactivity, which could also be confirmed in a patient presenting a mixed ventilatory failure. Isolated air entrapment could be observed in 2 patients, which could indicate disfunction of small airways in these cases. There was no correlation between functional respiratory failure and clinical activity of SLE, duration of the disease, other organ involvement, treatment and/or serum antibodies. Given that a great number of these functional lung anomalies (42%) exist in the absence of any clinical and radiological anomalies and that an important subgroup of patients are responsive to bronchodilators, we consider that the systemic evaluation of lung function must be obliged in the clinical treatment of SLE patients.

Adolescent↗