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Biomedical subjects

R Georges

Publications and source records attributed to R Georges.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Chronic idiopathic eosinophilic pneumopathy. Carrington's disease].

Eleven cases of idiopathic chronic eosinophilic pneumonia were studied. Ten of the patients were followed up for more than 3 years and the last one for 15 years. The female predominance observed, the mean age of 51 years, the late manifestations of asthma-like symptoms preceding the systemic signs by 8 1/2 months on average and the scarcity of extra-pulmonary manifestations characterized the clinical data. The most frequent radiological signs were non-systematized, bilateral alveolar opacities in the axillary and apical regions, sometimes migratory and giving in 9 cases a mirror image of pulmonary oedema. Beside this major inflammatory syndrome, blood eosinophilia was present in 10 patients with 4,500 eosinophils on average per cubic millimetre. Eosinophils were also present in the bronchoalveolar lavage fluid of those who underwent this examination. Both clinical and radiological signs responded to corticosteroids in all cases, with return to normal chest radiography within less than 10 days. Subsequently, the possibility of radiological relapse in the same or other territories, together with the development of a steroid-dependent intrinsic asthma accounted for the fact that after a follow-up of about 3 years corticosteroid therapy could not be discontinued in any of our patients.

Adult↗
PubMed1989

Exercise tolerance in chronic obstructive pulmonary disease: importance of active and passive components of the ventilatory system.

We investigated which components of ventilatory function are related to exercise tolerance in chronic obstructive pulmonary disease (COPD) patients. Physical characteristics, usual lung function, timing and neuromuscular components of ventilation were measured in 113 outpatients in whom FEV1/VC was less than 75% of the predicted value and exercise was limited by breathlessness. These variables were used to predict the maximum work load during progressive bicycle exercise. The prediction was obtained using a stepwise procedure in men and women separately. Among the variables selected, age, body weight, FEV1/VC, PImax, and P0.1/VT/TI accounted for 79% of the variability in maximum performance in men. The predictive model was statistically verified and was stable. The mean prediction error was 12 Watts. Among these variables, P0.1/VT/TI, PImax, and FEV1/VC were the main determinants of maximum work load (MWL). These results show that exercise limitation in COPD is related to impairment of both the active (inspiratory muscles) and passive (respiratory impedance) components of the ventilatory system. The same conclusions concerning passive components are proposed for women, despite a smaller population which prevented verification of the prediction.

Adult↗
PubMed1988

Smoking and pulmonary sarcoidosis: effect of cigarette smoking on prevalence, clinical manifestations, alveolitis, and evolution of the disease.

Patients with pulmonary sarcoidosis are less likely to smoke than persons of a similar age in the general population. This could be because smoking reduces the likelihood of developing sarcoidosis, or alternatively smoking could reduce the severity of the disease process so that smoking patients are underrepresented among patients with clinically overt disease. To evaluate these possibilities 64 patients with sarcoidosis of recent onset were studied at presentation and after a one year follow up period, clinical, functional, radiographic, and bronchoalveolar lavage fluid criteria being used to identify factors that might account for the lower incidence of sarcoidosis in smokers and to determine whether the disease is less severe in smoking patients. Smoking was less common in the patients with sarcoidosis (30%) than in the control subjects (46%). The study did not support the conclusion that sarcoidosis is less severe in smokers, as clinical, radiographic, and functional abnormalities were similar in smokers and non-smokers at initial evaluation and after a one year follow up period. Nevertheless, smoking did influence various indices used to assess disease "activity." Cigarette smoking was associated with a significant increase in the serum angiotensin converting enzyme activity (SACE), and patients with very high SACE and pulmonary gallium-67 uptake were smokers. Furthermore, more CD8+ (but not CD4+) lymphocytes were recovered by lavage from smoking than from non-smoking patients, giving a lower CD4: CD8 ratio in smokers. Fewer alveolar macrophages were recovered by lavage from smokers with sarcoidosis than from normal subjects with a similar smoking history. These finding support the possibility that smokers, particularly those with a prominent accumulation of alveolar macrophages in the lower respiratory tract, may be less likely to develop sarcoidosis.

Adult↗
PubMed1987

Role of mast cells in the pathogenesis of hypersensitivity pneumonitis.

To examine the possibility that mast cells have a central role in the pathogenesis of hypersensitivity pneumonitis, 20 patients with this disease were studied with the aim of seeking evidence for mast cell degranulation. The number of mast cells recovered by bronchoalveolar lavage from patients with hypersensitivity pneumonitis was more than 1,000 times greater than those recovered from normal individuals. Furthermore, discontinuation of antigen exposure resulted in an increase in the number of mast cells observed, consistent with the possibility that antigen exposure had induced mast cell degranulation. Cessation of antigen exposure also resulted in a rapid decrease in the number of neutrophils and eosinophils recovered by lavage, followed by an increase in the number of T8+ T lymphocytes present. In each case the time course of the changes was consistent with the possibility that mast cell degranulation had been important in regulating the number of the immune and inflammatory cells present in the lung. Histamine was present in lavage fluid supernatant from patients with hypersensitivity pneumonitis. The amount of histamine present was, however, closely correlated with the number of mast cells present and not with the interval since last antigen exposure. Delay in separating cells from lavage fluid supernatant resulted in an increase in histamine content. These results suggest that the free histamine in lavage fluid resulted from the degranulation of mast cells induced by the lavage procedure as histamine released in vivo has a short half life. We suggest that hypersensitivity pneumonitis results from a "late phase reaction" initiated by antigen induced mast cell degranulation.

Alveolitis, Extrinsic Allergic↗
PubMed1986

Smoking and interstitial lung disease. The effect of cigarette smoking on the incidence of pulmonary histiocytosis X and sarcoidosis.

Cigarette smoking produces marked alterations in the lung parenchyma and in the population of immune and inflammatory cells present in the lower respiratory tract. These cigarette-induced changes appear to influence the incidence of two different interstitial lung diseases, histiocytosis X and sarcoidosis. Smoking is a strong risk factor for the development of pulmonary histiocytosis X, since the incidence of smoking is very high among patients with histiocytosis X: 90% of the patients with histiocytosis X were smokers; 46% of the controls were smokers (p less than .001). In contrast, smoking appears to reduce the incidence of sarcoidosis: 31% of the patients with sarcoidosis were smokers (p less than .05 compared to controls). In an effort to understand how cigarette smoking influences the incidence of these two disorders, we compared the numbers and types of immune and inflammatory cells recovered by bronchoalveolar lavage from nonsmoking and smoking controls and patients with histiocytosis X and sarcoidosis. Although nonsmoking patients with histiocytosis X did not have a significant increase in the number of alveolar macrophages recovered by lavage (p greater than .2 compared to normals), smoking patients had an increase in the number of alveolar macrophages similar to that observed in the control population. In contrast, the number of macrophages recovered from patients with sarcoidosis who smoked was considerably less than that observed in normal smokers (p less than .05 comparing patients with sarcoidosis and controls who smoked 1-20 cigarettes/day). This difference in the intensity of the cigarette-induced macrophage alveolitis observed in the two patient groups may be important in explaining the opposite effects of cigarette smoking on the incidence of histiocytosis X and sarcoidosis.

Adult↗
PubMed1985

Resorptive versus absorptive hypercalciuria in sarcoidosis: correlations with 25-hydroxy vitamin D3 and 1,25-dihydroxy vitamin D3 and parameters of disease activity.

Sarcoidosis is frequently attended by hypercalciuria and sometimes by hypercalcaemia. The type of hypercalciuria and its relationships with disease extension and activity have rarely been investigated. In order to clarify these issues we undertook an investigation by a calcium absorption test in 39 patients with untreated thoracic sarcoidosis, and tried to establish correlations with vitamin D3 metabolism and some features of the disease. We found three types of responses. Group I (n = 12) with a normal test had normal 1,25-(OH)2D3 and rare extrathoracic localisations. Group II (n = 14) with absorptive hypercalciuria had higher serum calcium; 1,25-(OH)2D3 (p less than 0.001) and the free 1,25-(OH)2D3 index (p less than 0.05) were raised. Sarcoidosis was more often inflammatory, developing and disseminated. Group III (n = 13) had resorptive hypercalciuria, and hypercalcaemia was frequent. 1,25-(OH)2D3 (p less than 0.01) and the free 1,25-(OH)2D3 index (p less than 0.05) were raised but to the same degree as in Group II. Sarcoidosis was more disseminated and developing than in Groups I and II. In the 39 patients, iPTH and nephrogenous cAMP were low. Post-calcium load urinary calcium/creatinine (Ca/Cr) and 1,25-(OH)2D3 were correlated (p less than 0.05). Extrathoracic extension was associated with higher fasting urinary Ca/Cr (p less than 0.001), and development with higher post-load urinary Ca/Cr (p less than 0.001). Thus, absorptive hypercalciuria is related to the development of sarcoidosis and can be explained by high free 1,25-(OH)2D3, while resorptive hypercalciuria seems to be linked with disease extension. In such a case, the mechanism of osteolysis is not solely accounted for by high 1,25(OH)2 vitamin D3 serum levels, and we postulate that some other factor is at work, related to the extent of the granulomatous process.

Absorption↗
PubMed1984

Automatic monitoring of breath-to-breath occlusion pressure and ventilatory parameters during CO2 rebreathing.

A computerized system for occlusion pressure measurement during a rebreathing test is described. The system is implemented on an Apple II microcomputer. A set of programs allows calibration, data acquisition during the experiment, and fast automatic processing of the various parameters of ventilation and occlusion pressure versus end tidal PCO2. The use of a limited memory system is made possible by an electronic interface which allows preprocessing of the mouth pressure. In addition, that device drives a new simple electromagnetic valve with low flow resistance and dead space.

Biomedical Engineering↗
PubMed1984

Relative contribution of intrinsic lung dysfunction and hypoventilation to hypoxemia during hemodialysis.

Two mechanisms have been proposed to explain hemodialysis (HD)-induced hypoxemia: reversible lung damage due to intrapulmonary leukostasis as a consequence of the contact of blood with the dialyzer membrane, or alveolar hypoventilation due to the loss of carbon dioxide through the dialyzer. To assess the role of these factors, seven chronically uremic patients were studied before and during 4-hr HD sessions using a cuprophane membrane and either acetate (AHD) or bicarbonate (BHD) dialysate. In AHD only we observed, by comparison with predialysis values, a significant hypoxemia, and a decrease of alveolar ventilation (VA), lung carbon dioxide output, and respiratory exchange ratio. In both the AHD hypoxemic group and BHD nonhypoxemic group, there was a similar decrease in lung carbon dioxide diffusing capacity (DLCO) and of white blood cells (WBC), and a positive correlation between arterial oxygen pressure and VA without modification of alveolo arterial PO2 difference, an argument against the existence of ventilation-perfusion or ventilation-diffusion mismatching. We conclude that, although WBC sequestration induced a lung damage evidenced by DLCO impairment, the key factor of hypoxemia observed in AHD was the hypoventilation.

Acetates↗
PubMed1984

The relationship between disease duration and noninvasive pulmonary explorations in sarcoidosis with erythema nodosum.

In order to investigate the initial course of pulmonary sarcoidosis, the following investigations were carried out in 14 nonsmoking patients with Logfren 's syndrome 3 to 12 wk after the onset of erythema nodosum (EN): bronchoalveolar lavage (BAL) (cellular and protein components), serum assays of lgG and of the activity of angiotensin-converting enzyme (SACE), and pulmonary function tests. These results were related to the disease duration, estimated by the time lapse separating the onset of EN from the investigations. All patients but one showed a large increase in the percentage of lymphocytes (%-L) in BAL fluid (more than 30%). Although each patient was evaluated only once, and thus this work was not an actual longitudinal study, a linear relationship between lymphocyte count per milliliter of recovered fluid during BAL (L-count) and disease duration was found during the first 8 wk (r = 0.78, p less than 0.01), suggesting a fast-developing alveolitis. The delayed rise in SACE level may indicate a secondary activation of macrophages; SACE and L-count were well related, either up to 8 wk (SACE versus L-count: r = 0.84, p less than 0.01) or up to 12 wk (SACE versus L-count: r = 0.61, p less than 0.01). Serum lgG levels were found to follow the L-count (serum lgG versus L-count: r = 0.79, p less than 0.01) and appeared to be a reliable index of disease activity. Respiratory function showed a univocal pattern, with a marked decrease in all of the patients in carbon monoxide diffusing capacity (DLCO), contrasting with normal lung volumes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

Pulmonary sarcoidosis with an alveolar radiographic pattern.

Thirty-three cases of sarcoidosis (4.4% of 746 patients) showed an alveolar radiological pattern. A study of pulmonary function was carried out in 25 patients and compared with that of 46 patients with the interstitial radiological type of sarcoidosis. Twenty-two cases have been followed up from one to six years after the initial examination. The radiographic lesions were most often bilateral and included nodules greater than 15 mm with ill-defined margins or diffuse, infiltrative, non-retractile opacities with fluffy margins. Bilateral mediastinal lymph nodes were present in 27 patients. In 20 patients an associated reticulation was found on radiography. In four patients an open lung biopsy was done. The granulomatous nodules were identical to those found in other forms of sarcoidosis, although they were more confluent in the affected areas. Clinical and functional findings did not differ from those in the more common forms of sarcoidosis. Alveolar sarcoidosis has a sudden course. The alveolar radiological patterns always disappeared, with or without steroid treatment, while reticular patterns persisted in four patients. Rapid radiological changes were observed. Some functional abnormalities persisted in cases that were followed. It is concluded that alveolar sarcoidosis is a distinct acute form of sarcoidosis.

Adolescent↗
PubMed1982

Nonlinear fluid systems identified by random noise input.

The usual impedance measurement by Fourier analysis leads to undetectable errors when applied to nonlinear fluid systems where a nonlinear pressure drop p = K X V2 adds to the linear pressure-flow relationship, but processing series of impedance data with various input levels allows the measurement of such systems. This new method has been tested on simulations, nonlinear resistances, and intubation tubings. It gives accurate estimates of the nonlinear coefficient K together with the true linear impedance of the measured system. This way, the usual respiratory impedance measurement may be applied to intubated patients, as the respiratory impedance of the subject can be separated from the nonlinear behavior of the endotracheal tube or cannula.

Airway Resistance↗
PubMed1980

[Diffuse interstitial pneumopathy associated with limited Sjögren's syndrome (author's transl)].

Diffuse interstitial pneumopathy was found to be associated with limited Sjögren's syndrome (i.e. without connective tissue involvement) in 5 women aged from 48 to 83 years. The respiratory symptoms (dyspnoea, unproductive cough and crepitations) appeared before the dry-eye-and-mouth syndrome was diagnosed in two patients and several years afterwards in three. Respiratory function studies showed a mixed restrictive and obstructive syndrome, perturbed Co transfer and increased total expiratory airways resistance. These changes reflected the underlying pathology, as revealed by bronchial and lung biopsies, which consisted of lymphocyte and plasmocyte infiltration and fibrosis of the interalveolar septa, peribronchial spaces and bronchial glands. Abnormal respiratory function tests in 5 other patients without any respiratory symptom suggest that subclinical and subradiological lesions of the lungs and bronchi are not uncommon in Sjögren's syndrome.

Aged↗
PubMed1980

Identification of transducer defect in respiratory impedance measurements by forced random noise. Correction of experimental data.

The measurement of respiratory impedance by means of the forced oscillations technique depends on the frequency response of various measurement devices: pressure transducers, flowmeter, filters, etc. In the range of frequencies where measurements were done (0--100 Hz) it is difficult to have the same response (amplitude and phase) for mouth pressure and flow transducers. It is possible to identify the relative frequency response of both devices. This can be done by comparison of measurements made on a well-defined mechanical system with a theoretical model representing this system. The method also avoids separate frequency calibrations of pressure and flow. Its validity depends only on the accuracy of the model of impedance of the standard system used.

Airway Resistance↗