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Biomedical subjects

F Chabot

Publications and source records attributed to F Chabot.

At least 55 records · Page 3Linked to original sources
PubMed1994

Loss of lymphocyte modulatory control by surfactant lipid extracts from acute hypersensitivity pneumonitis: comparison with sarcoidosis and idiopathic pulmonary fibrosis.

Surfactant components are recognized to exert a regulatory control on lymphocytes in physiological conditions, as testified by in vitro studies. However, what happens following lung injury has not been established. As surfactant composition is altered in interstitial lung diseases, this work was carried out to compare the modulatory impact of normal human alveolar fluids on lymphocyte proliferation, with that from inflammatory lung diseases which are characterized by distinct patterns of immunologically-mediated alterations (i.e. sarcoidosis, acute hypersensitivity pneumonitis, idiopathic pulmonary fibrosis). Thymidine incorporation of allogeneic normal human blood lymphocytes was studied in the presence of total alveolar fluids or lipid extracts from 37 subjects, and phytohaemagglutinin (PHA) as T-cell mitogen. The results show that: 1) total alveolar fluids and lipid extracts from normal subjects share a concentration-dependent suppressive activity on T-cell proliferation; 2) total alveolar fluids from diseased patients have lost this property, either by a lack of suppressive activity (i.e. idiopathic pulmonary fibrosis) or even by enhanced activity (i.e. sarcoidosis and hypersensitivity pneumonitis); 3) lipid extracts from diseased patients still retain the suppressive activity of normal subjects, except for hypersensitivity; and 4) an imbalance in surfactant phospholipids with an increase in the inducers to suppressors ratio is more likely to explain this alteration in hypersensitivity pnuemonitis than changes in total lipid content. In conclusion, alveolar lipid extracts from acute hypersensitivity pnuemonitis have lost the modulatory control normally exerted by surfactant lipids on lymphocyte proliferation in vitro. This alteration may contribute to the invasion of the lung by lymphocytes in acute hypersensitivity pnuemonitis in vivo.

Adult↗
PubMed1993

Early effects of short-time cigarette smoking on the human lung: a study of bronchoalveolar lavage fluids.

We investigated the early effects of cigarette smoking in healthy subjects by means of lung lavage, looking at markers of alveolar permeability, the alveolar cell profile, the immunophenotyping of macrophages and lymphocytes, and the level and profile of surfactant phospholipids. Bronchoalveolar lavages (BAL) were performed in 33 healthy subjects [20 nonsmokers (nS), 13 moderate and short-time smokers (S)]. In the acellular supernatants we measured the markers of alveolar permeability (i.e., total proteins, albumin, albumin/urea), the alveolar epithelial lining fluid (AELF), the surfactant amounts and profile, and explored the blood lymphocytes by in vitro exposure. The cell pellet established the alveolar formula and a membrane mapping of macrophages (LFA-1 and HLA-DRII expression) and lymphocytes (CD4, CD8, LFA-1, HLA-DRII expression). We found no significant increase of alveolar permeability in our smokers, but an increased alveolar cellularity (more than 3-fold vs nS, P < 0.05) evenly distributed between sub-populations except for an enhanced number of eosinophils in smokers (P < 0.05 vs nS). Smokers' alveolar macrophages had an overloaded cytoplasm, a decreased percentage of antigen-handling cell expression (HLA DRII: P < 0.05 vs nS) and a low percentage of cell to cell adhesion molecule expression (LFA-1: P < 0.05 vs nS). Smoking history and LFA-1 expression on alveolar macrophages were interrelated. Smokers' alveolar lymphocyte subsets were more often T suppressor cells (CD8+) and had an increased percentage of antigen-presenting cell expression (HLA DRII: P < 0.05 vs nS). Smokers' BAL fluid did not show the inhibitory control of phytohemagglutinin-induced lymphocyte proliferation present in nonsmokers' fluids. Surfactant phospholipid amounts were similar, but phosphatidylethanolamine was raised and the ratio of phosphatidylcholine to sphingomyelin decreased in smokers (P < 0.05 vs nS). We observed specific cellular and biochemical alterations in the lung lavage of short-time smokers. Alveolar macrophage and lymphocyte expression of LFA-1 and HLA-DR II molecules was altered. Smokers' alveolar fluids lost the physiologic regulatory control of T mitogen-induced lymphocyte proliferation. Membrane phospholipids released by cellular damage increased early in tobacco-exposed lung fluids. This profile of alterations may be an early and sensitive marker of smoking-induced lung damage.

Adult↗
PubMed1993

Pulmonary arterial wedge pressure measurement can modify pulmonary haemodynamics in patients with chronic lung disease.

In 20 patients with chronic lung disease in stable condition, haemodynamic values were compared during wedging of a Swan-Ganz catheter, either in a distal branch of the pulmonary artery, or by balloon inflation (with 1 ml) in a proximal branch, mostly excluding right lower lobe perfusion. Average pulmonary arterial wedge pressure, systemic arterial pressure, transcutaneous and mixed venous oxygen saturation, cardiac output and pulmonary blood volume (PBV) were not statistically different during distal and proximal wedging, but systolic pulmonary arterial pressure and pulmonary vascular resistance were slightly higher during balloon inflation (P < 0.05). In four patients, PBV decreased by 20% or more; cardiac output was reduced and mean systemic arterial pressure diminished by 10 mmHg or more in three patients. Of the two patients with the lowest PBV, one did not tolerate the balloon inflation because of dyspnoea, and the other showed dramatically haemodynamic changes. These were more likely to occur when the occlusion lead to the exclusion of a still well perfused area. Our results support optimal matching between ventilation and perfusion in patients with chronic lung disease, although both are inhomogeneous. When pulmonary vascular restriction can be suspected, pressure obtained during catheter wedging by balloon inflation should be interpreted with caution. Monitoring arterial oxygen saturation and systemic arterial pressure before and during the manoeuver could help to diagnose haemodynamic effects of the balloon inflation in a proximal pulmonary artery.

Adult↗
PubMed1993

Right ventricular pressure-volume relations in chronic lung disease.

Thirty-four patients with chronic lung disease in stable condition were studied at supine rest (RS), at rest with the legs raised (LR), and during two levels of exercise: E1, 0 or 20 W, E2, 20 or 40 W. Five patients had normal spirometry (group 1), six patients had normal vital capacity but FEV1/VC below 70% (group 2), and 23 patients had VC below 95% of normal and FEV1/VC below 70% (group 3); group 3 was subdivided into group 3a (n = 14) without, and group 3b (n = 9) with a history of right heart failure (RHF). Right ventricular end-diastolic (RVEDV) and end-systolic (RVESV) volumes were computed from stroke volume and right ventricular ejection fraction (RVEF). RVEF at rest was correlated with lung function variables. Changes in RVEF from LR to E2 were normal, i.e. above 0.05, except for in group 3b, where RVEF did not increase with exercise. Relation between RVESV and pressure, and changes in stroke volume with RVEDV from LR to E2 were also abnormal in group 3b. These results show that in patients with chronic lung disease RVEF at rest reflects lung function, whereas its adaptation to exercise is impaired only in patients who have experienced RHF episodes.

Blood Pressure↗
PubMed1993

Peripheral pulmonary vascular resistance.

The pressure-flow relationship has been studied in a peripheral portion of the lung vasculature in anesthetized dogs with use of a double-lumen catheter wedged in a distal pulmonary artery. One lumen was used to infuse mixed venous blood in the wedged area and the other to measure the corresponding perfusion pressure. Flow ranged from 0 to 9.2 ml/min, and the mean volume of the wedged area (n = 59) was 0.75 +/- 0.05 (SE) ml. In the areas where the distal pulmonary artery was in the same direction as the catheter ("coaxial"), the mean pressure-flow curve showed a negligible gamma-intercept and no significant difference between ascending and descending flow. The slope of the initial part of the ascending limb (peripheral pulmonary vascular resistance) varied from site to site and did not show a significant correlation with the overall pulmonary vascular resistance; it was inversely correlated with the volume of the wedged area (r = -0.35, P < 0.05) and directly, as expected, correlated with the y-intercept (r = 0.78, P < 0.001) and hysteresis (r = 0.48, P < 0.001). The results of two consecutive pressure-flow runs in the same site showed similar results, with no difference exceeding the error of measurement. In contrast, the slope increased by 71% during hypoxia (fraction of inspired O2 was 0.10, n = 5). This procedure seems suitable to determine the effects of physiological or pharmacological interventions on the pulmonary vessels, without interference of the systemic circulation.

Animals↗
PubMed1993

Respiratory mechanics studied by forced oscillations during artificial ventilation.

Potential advantages of the forced oscillation technique over other methods for monitoring total respiratory mechanics during artificial ventilation are that it does not require patient relaxation, and that additional information may be derived from the frequency dependence of the real (Re) and imaginary (Im) parts of respiratory impedance. We wanted to assess feasibility and usefulness of the forced oscillation technique in this setting and therefore used the approach in 17 intubated patients, mechanically ventilated for acute respiratory failure. Sinusoidal pressure oscillations at 5, 10 and 20 Hz were applied at the airway opening, using a specially devised loudspeaker-type generator placed in parallel with the ventilator. Real and imaginary parts were corrected for the flow-dependent impedance of the endotracheal tube; they usually exhibited large variations during the respiratory cycle, and were computed separately for the inspiratory and expiratory phases. In many instances the real part was larger during inspiration, probably due to the larger respiratory flow, and decreased with increasing frequency. The imaginary part of respiratory impedance usually increased with increasing frequency during expiration, as expected for a predominately elastic system, but often varied little, or even decreased, with increasing frequency during inspiration. In most patients, the data were inconsistent with the usual resistance-inertance-compliance model. A much better fit was obtained with a model featuring central airways and a peripheral pathway in parallel with bronchial compliance. The results obtained with the latter model suggest that dynamic airway compression occurred during passive expiration in a number of patients. We conclude that the use of forced oscillation is relatively easy to implement during mechanical ventilation, that it allows the study of respiratory mechanics at various points in the respiratory cycle, and may help in detecting expiratory flow limitation.

Adult↗
PubMed1992

[Viral pneumopathies after heart transplantation. Radioclinical analysis].

From a retrospective study of 80 cases of heart transplantation, the contribution of chest X-rays to the diagnosis of viral pneumonia was studied. Among 66 episodes of pneumonia, a viral cause was proved in 16 cases (CMV: 9, Herpes: 7), with 13 cases during the first 4 months. CMV pneumonia was revealed in 3 cases by a diffuse pulmonary infiltrate with a rapidity fatal outcome and in 6 cases by focal infiltrates that disappeared within 1 and 7 weeks. Herpes pneumonia was immediately revealed, in 5 cases, by a diffuse infiltrate. In 11 out of 16 cases, the viral pneumonia improved but its course was complicated by the development of another pneumonia.

Cytomegalovirus Infections↗
PubMed1992

[Drug-induced pulmonary diseases: diagnostic, therapeutic and prognostic aspects. Apropos of 10 personal case reports].

The authors report ten cases of drug induced lung diseases, complicated by respiratory failure of whom five were attributed to cytotoxic drugs and five to non cytotoxic drugs. The drug induced lung disease presented as acute respiratory distress syndrome in two cases, alveolar interstitial lung disease in three cases, purely interstitial in five cases. There was acute respiratory failure (ARF) in eight cases and chronic respiratory failure (CRF) in two cases. Among the five patients admitted for cytotoxic drug induced lung disease and ARF, four recovered and one died of diffuse destructive pulmonary fibrosis. Among the five patients having non cytotoxic drug induced lung disease, three were in ARF and recovered. The other two had CRF and died of diffuse pulmonary fibrosis. The diagnostic of drug induced lung disease was established in each case with the chronology of the clinical events, the exclusion of other possible causes of the lung disease and the evolution after removal of the incriminated drug. Broncho-alveolar lavage (BAL) had a major diagnostic value. It was contraindicated by respiratory failure in five cases. The predominant alveolar cell type was lymphocyte (four cases), eosinophil (three cases) and neutrophil (one case), BAL was realized with a provocation test and demonstrated the pathogenic role of cyclothiazide in one case. No specific information was given by histology. The prognosis did not seem to be linked to the severity of the initial clinical picture, or to the nature of the underlying neoplastic disorder, but to the degree and evolution of the pulmonary fibrosis.

Adrenal Cortex Hormones↗
PubMed1992

Respiratory mechanics studied by multiple linear regression in unsedated ventilated patients.

Respiratory mechanics during artificial ventilation are commonly studied with methods which require a specific respiratory pattern. An alternative is to analyse the relationship between tracheal pressure (P) and flow (V') by multiple linear regression (MLR) using a suitable model. The value of this approach was evaluated in 12 unsedated patients, mechanically-ventilated for acute respiratory failure, and most with a history of chronic obstructive or restrictive respiratory disease. After correction for the non-linear resistance of the endotracheal tube, the data were analysed with the linear first order model: P = P0 + E.V + R.V' where E and R are total respiratory elastance and resistance, and P0 is the static recoil pressure at end-expiration. After exclusion of the cycles which clearly exhibited muscular activity, a good fit was observed in 25 out of 36 records (relative root-mean-square error less than 10%); the values of E and R were reproducible within cycles, and consistent with the patient's condition and the ventilatory mode. The intrinsic positive end-expiratory pressure (PEEPi), as derived from P0 and the applied PEEP, averaged 1.1 +/- 1.0 hPa. Using more sophisticated models, allowing for mechanical non-homogeneity or non-linearity of R or E, rarely improved the fit and often provided unrealistic data. In several subjects the discrepancy between the data and the first order model was consistent with expiratory flow limitation, which may severely impair the analysis. We conclude that, except in the case of expiratory flow limitation, the method is useful for routine clinical use and better implemented with the simple linear model.

Aged↗
PubMed1992

[Fibrosing pneumopathy induced by cyclothiazide. Apropos of a case].

A diffuse interstitial pulmonary fibrosis associated with an idiopathic hepatic cirrhosis occurred in a 79 years old man treated during five years with cyclothiazide and triamterene for a mild systemic hypertension. The outcome was fatal. A provocation test was positive with BAL lymphocytic reaction. Cyclothiazide induced fibrosis is likely.

Aged↗
PubMed1991

[Respiratory pasteurellosis. Apropos of 32 cases].

The authors present the main characteristics of respiratory pasteurellosis on the basis of 32 personal cases. The predominant background is chronic obstructive lung disease consecutive, in most cases, to chronic bronchitis. In patients without chronic lung disease the infection occurs when the terrain is deficient. The most common clinical form is bronchitis; pneumonia, pleurisy and lung abscess are rare. The existence of asymptomatic carriers has been recognized. Clinical manifestations are devoid of pathognomonic signs and symptoms. Diagnosis rests on isolation of the micro-organism and can be completed by serodiagnosis and intradermal reaction to pasteurelline. The severity of respiratory pasteurellosis depends on the clinical form and the background. The curative treatment is simple and effective as a rule, but prevention is possible and recommended since pasteurellosis is a potentially severe infection.

Aged↗
PubMed1989

Double blind study on the efficacy and safety of tetrabamate and chlordiazepoxide in the treatment of the acute alcohol withdrawal syndrome.

1. Efficacy and safety of tetrabamate and chlordiazepoxide in the treatment of the acute or Primary Alcohol Withdrawal Syndrome (PAWS) were assessed during a randomized double blind clinical trial, carried out on sixty male alcoholic in-patients. 2. The two drugs were administered four times a day in double dummy conditions, according to a fixed-flexible decreasing dosage schedule (six days basic regimen). 3. Drug efficacy was measured daily throughout the study period using a battery of standard instruments for collecting quantitative clinical, behavioral, psychopathological and laboratory data. Side effects were daily recorded. 4. Tetrabamate was found to be as efficient as chlordiazepoxide in reducing the intensity of the PAWS, improving sleep and vital signs rapidly and alleviating anxiety progressively. 5. Tetrabamate was found particularly beneficial for severe tremor. Psychomotor and mood scores consistently favored tetrabamate, suggesting psychoanaleptic properties of this compound (increased diurnal vigilance). 6. Side effects were minimal with tetrabamate and generally of weak intensity with chlordiazepoxide. 7. The results of this study indicate that tetrabamate may represent a new alternative drug of choice for the therapy of the acute alcohol withdrawal syndrome.

Adult↗
PubMed1986

Nosology and diagnosis of alcoholism. Issues and perspectives in subtyping (DSM III) simple alcoholism and alcoholism associated with other psychopathologies.

The presence of psychopathological syndromes in alcoholic in-patients was assessed using the NIMH-Diagnosis. The most stricking finding of this study was the high percentage of additional psychopathological syndromes associated to alcoholism. Based on this finding, a tentative classification of alcoholism is proposed. The urgent need for a comprehensive diagnostic scheme for alcoholism is underlined.

Alcoholism↗
PubMed1978

Nucleotide sequence relationships between the genomes of an endogenous and an exogenous avian tumor virus.

We have used mapping of large T1 oligonucleotides to examine the genome of Rous-associated virus-O (RAV-O), an endogenous virus of chickens, and to compare it with that of Prague strain Rous sarcoma virus, subgroup B, (Pr-RSV-B), an exogenous sarcoma virus. To extend the sensitivity of such comparisons, we have developed a system of nucleic acid hybridization and hybridization-competition combined with fingerprinting. This method allows us to estimate the relative degree of relatedness of various portions of the viral genomes. From the results of this study, we have concluded that the genomes of Pr-RSV-B and RAV-O are related in the following way. The 5'-terminal half of the genomes (corresponding to the gag and pol regions) is virtually identical, with only scattered single nucleotide differences. This region is followed by a region comprising 25 to 30% of the genome (the env region) which contains substantial nucleotide sequence differences, most or all of which are due to single base changes. The env-coding region can be further subdivided into three regions: a more variable region probably containing sequences coding for subgroup specificity, flanked by relatively common sequences on each side. To the 3' side of the env region, the RAV-O genome contains a very short sequence not found in Pr-RSV-B, whereas the Pr-RSV-B genome contains a much longer unrelated sequence. The central portion of this sequence comprises the src gene as defined by transformation-defective mutants. Particularly striking is the absence, in the RAV-O genome, of any nucleotide sequence related to the "c region" found very near the 3' end of all exogenous tumor viruses. Both the Pr-RSV-B and RAV-O genomes contain the identical terminally redundant sequence of 21 nucleotides near each end of the genome.

Avian Leukosis Virus↗