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Biomedical subjects

M Letourneux

Publications and source records attributed to M Letourneux.

At least 19 recordsLinked to original sources
PubMed2002

Incidence of digestive cancers and occupational exposure to asbestos.

While the role of exposure to asbestos in the development of several cancers such as mesotheliomas and bronchopulmonary cancers is now well established, the possible relationship between digestive cancers, other than peritoneal mesotheliomas, and occupational exposure to asbestos is still controversial. The great majority of the studies are based on mortality data. The aim of the study was to analyse the relationship between digestive cancer incidence and occupational exposure to asbestos in a population of subjects for whom precise occupational exposure data and precise incidence data were available. The population consisted of salaried and retired workers from a company using asbestos to manufacture fireproof textiles and friction materials. There were 1454 men (79.9%) and 366 women (20.1%). A cumulative exposure index and a mean exposure concentration in fibres/ml for each subject were calculated with the aid of an in-house job-exposure matrix. The number of cases of digestive cancer observed was compared with the expected and Standardized Incidence Ratio (SIR) was estimated. Precise occupational exposure data allowed us to study the dose-response relationship between asbestos exposure and risk of digestive cancer using Cox model. Fifty-six digestive cancers occurred in the study population over the 18-year follow-up period for 48.4 expected (SIR = 1.16 [0.87-1.50]). Comparing with incidence in the county, SIR was not significant for any of the digestive localization, but for peritoneum. However, even after taking into account the potential confounders via the Cox model, there was a significant dose-response relationship between the occurrence of digestive cancers and the mean exposure concentration, even after exclusion of peritoneum cancers. Our study provides initial evidence suggesting a relationship between occupational exposure to asbestos and the risk of digestive cancer: first, it is a study of incidence although the risk evidenced is not significant; secondly, a dose-effect relationship is demonstrated in the whole population. However, these preliminary results require confirmation by more powerful studies focusing on larger series.

Adult↗
PubMed2002

Asbestos bodies in the sputum of asbestos workers: correlation with occupational exposure.

A cross-sectional medical survey including collection of three consecutive sputum samples was carried out among 270 retired workers of a textile and friction materials factory, in order to investigate the relationship between asbestos body identification and asbestos exposure. The individual cumulative asbestos exposure, determined by means of a plant-specific job-exposure matrix based on asbestos air measurements in the workshops, proved to be heavy with a mean cumulative exposure of 217 fibres x mL(-1) x yr. Macrophages and asbestos bodies were identified in sputum samples by light microscopy. The lung origin of the sputum, suggested by the presence of macrophages and/or asbestos bodies, was confirmed in 82.6% of subjects, and 53% of these samples were positive for asbestos bodies. The prevalence of asbestos bodies was not related to sex, smoking status or latency. Conversely, multivariate analysis showed a positive relationship with cumulative exposure, duration and intensity of exposure to asbestos, as well as age and time since retirement. These findings suggest that sputum analysis for asbestos bodies may remain a relevant and noninvasive marker of heavy occupational exposure to asbestos, even years after retirement. Owing to the new perspectives in lung cancer screening, it might contribute to the identification of high-risk subjects.

Aged↗
PubMed2001

[Malignant mesothelioma in Basse-Normandie, a French population study. Descriptive analysis, prognostic factors and survival].

BACKGROUND: Malignant mesothelioma is a pleural and/or peritoneal tumor closely related to asbestos exposure, and its incidence should continue to increase during the first two decades of the 21(rst)century. The main prognostic factors described for this tumor are older age, sex, tumor stage and histological type. The aim of this study was to assess the incidence of pleural and peritoneal malignant mesothelioma in the County of Basse-Normandie (France), as well as their epidemiological characteristics, and the prognostic factors related to survival duration. METHODS: Cases were identified through repeated inquiries among all chest physicians and pathologists of the County of Basse-Normandie. A special care was taken in the validation of the diagnosis of each case. Incidence of mesothelioma was determined according to sex and age (5 years categories). Qualitative and quantitative variables were compared with the use of chi-square or Student's t tests respectively. Survival rate was calculated by Kaplan-Meier method, and prognostic factors were studied by means of Cox model. RESULTS: Study population consisted in all 80 malignant mesothelioma cases diagnosed in Basse-Normandie between the 1(rst) of September 1995 and the 31(rst) of August 1999. Annual incidence rates of pleural mesothelioma were 1.1/100 000 in men and 0.23/100 000 in women; annual incidence rates for peritoneal mesothelioma were 0.21/100 000 in men and 0.13/100 000 in women. Asbestos exposure was present in 63 cases (78.8%). The study of geographic distribution of mesothelioma cases revealed the influence of the main asbestos industrial settings, as well as the numerous scattered cases related to other occupational exposure. Mean survival duration was 9 months for pleural mesothelioma and 5 months for peritoneal mesothelioma. After adjustment on age, death risk was higher in asbestos-exposed than in non asbestos-exposed cases. CONCLUSION: This study confirms that malignant mesothelioma is closely related to asbestos exposure, but not only in main asbestos industrial settings. It suggests that asbestos exposure may take place among prognostic factors of this tumor.

Age Factors↗
PubMed1999

[Nonmalignant asbestos-related diseases].

Non malignant asbestos diseases are dominated numerically by pleural plaques. This form of circumscribed fibrosis of the parietal pleural is generally asymptomatic and its potential for evolution is weak. More rarely diffuse pleural fibrosis results from disease of the visceral pleura with a secondary fusion of the two pleural layers. Usually it follows a pleural effusion which resolves spontaneously. Its functional effects are sometimes important. The generalised practice of computerized tomographic scanning as a work up for asbestos related disease has revealed the frequent association of this diffuse pleural fibrosis with a particular form of peripheral pulmonary collapse called round atelectasis. Asbestosis or pulmonary fibrosis induced by the inhalation of asbestos has become rarer due to the improvement in working conditions in the asbestos industry. It develops following heavy exposure. The frequency of bronchopulmonary cancer is increased when asbestosis exists although it is not currently possible to say if the two disorders are independent and each is only conditioned by exposure to asbestos or if the two diseases are inextricably linked by the same physiopathological process.

Asbestos↗
PubMed1999

[Risk assessment of benign asbestosis (dose-effect relationship, time-effect relationship, co-factors)].

Despite the lack of precision of asbestos exposure assessments and the limitations of the main diagnostic epidemiological tool for asbestos-related diseases (i.e. standard X ray films), several issues concerning the risk of development of asbestos-related diseases are well established. For asbestosis, now a rare disease, the existence of a positive dose-response relationship, with a threshold or no-effect level, has been clearly demonstrated. The slope of the relationship curve is steeper for amphiboles than for chysotile, as it is for increased fiber length. Asbestosis is associated with an increased risk of bronchial carcinoma, however it is now known that exposure to asbestos of itself increases the risk of cancer even in the absence of any radiographic signs of pulmonary fibrosis. Pleural plaques occur even when the level of asbestos exposure is low. They are not only dose-dependent but are also latency-related. They have no prognostic significance in asbestos-exposed workers, but are associated with an increased risk for the subsequent development of mesothelioma and bronchial carcinoma when compared to the risk of the general population. Diffuse pleural thickening is associated with higher levels of asbestos exposure than those associated with pleural plaques. It usually follows a benign pleural effusion, which is a less frequent but earlier consequence of asbestos exposure than the other asbestos-related diseases documented above.

Asbestosis↗
PubMed1999

[Medical impact of screening of benign pleural lesions associated with the inhalation of asbestos dust].

Asbestos-related benign pleural lesions can involve the parietal pleura (pleural plaques), and/or visceral pleura as focal or diffuse (diffuse pleural thickening) fibrosis. Benign asbestos pleurisy and rounded atelectasis are linked with visceral pachypleuritis, the former as a cause, the latter as a consequence. The prevalence of these lesions, particularly pleural plaques, is very high, reaching 25% in populations of workers exposed intermittently to asbestos. Conventional radiology has a sensitivity less than 50% for detection of plaques, and a specificity less than 85%. Tomodensitometry is today the reference diagnostic tool: availability, cost and irradiation have to be considered before its use in mass screening. Pleural plaques are most often asymptomatic and a functional impairment cannot be proven usually on an individual basis. Visceral pleural thickening is more often accompanied by symptoms (dyspnea, pain) and functional impairment. There is no treatment susceptible to produce a regression of pleural lesions. Asbestos exposure increases the risk of pulmonary and pleural cancers. However there is no evidence of an increased risk in subjects with plaques compared with subjects without plaques but an equivalent asbestos exposure. The cost and the risk of diagnostic procedures induced by the screening, as well as the anxiety provoked by the detection of radiologic abnormalities are to be considered. Finally it is difficult today to justify the screening of benign pleural lesions by arguing an improvement of the life expectancy or of the quality of life of former asbestos exposed workers. It is probable that benefit of a screening will be of a social type, at an individual or a collective level.

Air Pollution↗
PubMed1999

[Asbestosis].

Asbestosis is a rare pneumoconiosis secondary to inhalation of asbestos fibers. It follows sufficient professional exposures (more than 25 fibers x years/ml). The mean latency is 20 years. Clinical symptoms include exertion dyspnea, crackles and clubbing. Chest radiography the performances of which have been enhanced by the use of the ILO score shows fine reticular or reticulonodular opacities which predominate in pulmonary bases often in association with benign pleural abnormalities. An ILO score equal or higher than 1/1 is suggestive of asbestosis in the context of a compatible professional history. Pulmonary function is typical of diffuse interstitial lung disease. High resolution CT is the most performance investigation in particular in presence of asbestosis either minimal or of recent origin. The diagnosis of asbestosis is based on the professional exposure, a compatible interstitial lung and pleural disease and the exclusion of alternative hypothesis. The diagnosis can be comforted by bronchoalveolar lavage (cytology and biometeorology). Various evolutions are possible: stability, progression to respiratory insufficiency, increased incidence of bronchial carcinoma. Life expectancy is reduced in severe cases. There is no efficient medical treatment. Asbestosis is recognized as a professional disease. A better recognition of asbestosis necessitates a performance policy of depistage in populations with significant present or past exposure and an appropriate diagnostic strategy including high-resolution-CT.

Asbestosis↗
PubMed1999

[Prevention programs for people exposed to asbestos: results of the ongoing activities].

Programs of prevention concerning the populations exposed or having been exposed to asbestos include on the one hand, specific programs of medical surveillance and on the other hand, interventions of primary prevention. The latter were essentially anti-smoking campaigns and chemo-prevention trials of lung cancer through taking of vitamin A derivatives. In the first part of this review, the results of the experiments of the medical follow, up organized in France and abroad will be shown. These studies allow particularly to appraise both the usual latency of appearance of lung pathologies due to asbestos and the contribution of thoracic scanography in their diagnosis. The interest of the new techniques, such as the autofluorescence fiberscopy, is tackled too. The studies on primary prevention, detailed in the second part, underline the necessity to stop of tobacco consumption among the smokers exposed to asbestos. Moreover, this study concludes that the chemo-prevention of lung cancer through vitamin A derivatives is not yet effective. Some general principles which may be useful to the setting up programs of prevention are put forward in conclusion.

Aged↗
PubMed1999

[Screening of diseases associated with asbestos. On-going activities, synthesis].

Medical screening requires always assessment. On the basis of ongoing studies on occupational health asbestos programs, we suggest some recommendations for asbestos screening after occupational exposure. The proposal for asbestos workers post-exposure surveillance should take into account the medical but also the social aspects of the problem. Post-exposure screening of asbestos workers includes an evaluation of occupational exposure, compulsory basis medical check-up, the characteristics of the radiological investigations and schedule of the medical surveillance. In conclusion, we suggest some general recommendations for asbestos screening after occupational exposure, particularly the necessity to obtain a concerted approach of asbestos screening with regional and national networks, the concern of their assessment and the implementation of specific research studies.

Asbestosis↗
PubMed1998

[Asbestos-related diseases].

The growing use of asbestos in France like in other industrialized countries since the beginning of the century is the reason of the increase of asbestos-related diseases, which occur after long latency periods. From asymptomatic benign pleural plaques up to malignant mesothelioma of poor prognosis, the fibrogenic and carcinogenic properties of asbestos mainly concern occupationally exposed subjects. The Institut national de la santé et de la recherche médicale (INSERM) expert committee concluded that about 1,950 deaths due to asbestos-related cancers occurred in France in 1996. Reinforcement of French legislation aims at reducing all kinds of asbestos exposure.

Asbestosis↗
PubMed1998

SV40-like DNA sequences in pleural mesothelioma, bronchopulmonary carcinoma, and non-malignant pulmonary diseases.

Pleural and pulmonary malignancies are usually associated with well-known carcinogen exposure. Recently, the presence of simian virus 40 (SV40)-like DNA sequences has been detected in brain and bone-related human cancers and in pleural mesothelioma. In order to determine whether SV40-like DNA sequences are also present in bronchopulmonary carcinoma and non-malignant lung samples, 125 frozen pleural and pulmonary samples (including 21 mesotheliomas, 63 bronchopulmonary carcinomas, 8 other tumours, and 33 non-malignant samples) and 38 additional samples distant from tumours were studied for the occurrence of SV40-like DNA sequences by polymerase chain reaction (PCR) amplification followed by hybridization with specific probes. Sequences related to SV40 large T antigen (Tag) were present in 28.6 per cent of bronchopulmonary carcinomas, 47.6 per cent of mesotheliomas, and 16.0 per cent of cases with non-neoplastic pleural and pulmonary disease. No statistically significant difference in the occurrence of these DNA sequences was found between malignant mesothelioma and bronchopulmonary carcinoma, but a significantly higher number of mesothelioma cases exhibited SV40-like DNA sequences in comparison with cases of non-malignant pleural or pulmonary disease (P < 0.04). Among cases positive for SV40-like DNA sequences, a history of asbestos exposure was found in 3 out of 12 bronchopulmonary carcinomas and 8 out of 10 mesotheliomas. Immunohistochemistry using monoclonal antibodies directed against Tag did not demonstrate nuclear staining. The DNA sequences were not related to BK virus sequences, but three samples were positive with probes hybridizing with JC virus DNA sequences. In conclusion, this study demonstrates the presence of SV40-like DNA sequences in pulmonary neoplasms and in non-malignant lung tissues. It appears that the presence of SV40-like DNA is not unique to cancer.

Adult↗
PubMed1998

[Rolled atelectasis and asbestosis. Apropos of 26 patients].

Round atelectasis (AE) is a benign form of respiratory problem which develops due to fixing of the visceral pleura. This lesion for which the principal cause is exposure to asbestos may pose problems of differential diagnosis with bronchopulmonary cancer. In a cohort of 286 patients suffering from benign asbestos related pleural disease the diagnosis of round atelectasis was made on computerized tomography in 26 patients (31 AE) on the following criteria: rounded opacities of less than 7 cm in diameter situated at the periphery of the lung in contact with a thickened pleura with an acute angle linking the pleura and the opacity, a reduction of lung volume on the side of the atelectasis and the presence of a "comet tail sign". These patients were investigated to specify the circumstances of the occurrence, including their symptomatology, the changes in lung function, the topography of the round atelectasis and the associated radiological signs. Intense exposure to asbestos either continuous or discontinuous was found in 19 patients; 20 patients presented with some respiratory symptoms (dyspnoea 15/26, cough 11/26 and chest pain 9/26) but the reduction in lung function was moderate (7 had restrictive ventilatory trouble, 4 obstructive problems and a mixed problem in 1). The preferred localisation for round atelectasis was in the inferior lobes in the posterior basal lateral vertebral area (26/31) which may explain their being frequently missed on the standard radiograph (only one case of round atelectasis was visible on the straight chest radiograph in our study). An understanding of the pathology and the computered tomographic characteristics are now well defined and should enable an unnecessary diagnostic thoracotomy to be avoided which besides has no justification from the functional point of view.

Asbestosis↗
PubMed1998

Detection of SV40-like DNA sequences in pleural mesothelioma, bronchopulmonary carcinoma and other pulmonary diseases.

Mesotheliomas are pleural-based tumours mainly associated with asbestos exposure (70% of cases) and the incidence is still raising. Recently, a possible viral connection was reported and 60% of mesotheliomas were demonstrated to contain and express SV40-like DNA sequences. In this study, the presence of SV40-like DNA sequences were investigated in mesotheliomas (15 tissue samples and six cell lines) and in 63 additional bronchopulmonary carcinomas, one parietal osteosarcoma and non-malignant lung samples as well as in organizing pleuritis (8). Finally, 163 samples were analysed by the polymerase chain reaction (PCR) with a set of primers PYV.for and PYV.rev to amplify a 173 bp region of the SV40 Tag. and a 179 bp region JC virus (JCV) as well as a 182 bp region BK virus (BKV). PCR amplification and hybridization with a probe specific for SV40 Tag revealed that 47.6% of mesotheliomas, 28.6% of primary bronchopulmonary carcinomas and 16% of non-neoplasic lung diseases contained SV40-like DNA sequences. No statistically significant difference in the occurrence of these DNA sequences was found between malignant mesothelioma and bronchopulmonary carcinoma. However, a significantly higher number of mesothelioma cases exhibited SV40- like DNA sequences in comparison with non-malignant pleural and pulmonary tissues. The DNA sequences were not related to BK and JC virus sequences. These results indicate that SV40-like DNA sequences are present in mesotheliomas as well as in bronchopulmonary carcinomas and non-malignant pleuropulmonary diseases.

Antigens, Polyomavirus Transforming↗
PubMed1998

[Non-malignant asbestos-related diseases].

Non malignant asbestos diseases are dominated numerically by pleural plaques. This form of circumscribed fibrosis of the parietal pleural is generally asymptomatic and its potential for evolution is weak. More rarely diffuse pleural fibrosis results from disease of the visceral pleura with a secondary fusion of the two pleural layers. Usually it follows a pleural effusion which resolves spontaneously. Its functional effects are sometimes important. The generalised practice of computerized tomographic scanning as a work up for asbestos related disease has revealed the frequent association of this diffuse pleural fibrosis with a particular form of peripheral pulmonary collapse called round atelectasis. Asbestosis or pulmonary fibrosis induced by the inhalation of asbestos has become rarer due to the improvement in working conditions in the asbestos industry. It develops following heavy exposure. The frequency of bronchopulmonary cancer is increased when asbestosis exists although it is not currently possible to say if the two disorders are independent and each is only conditioned by exposure to asbestos or if the two diseases are inextricably linked by the same physiopathological process.

Asbestos↗
PubMed1997

Assessment of potential damage to DNA in urine of coke oven workers: an assay of unscheduled DNA synthesis.

OBJECTIVES: A study was conducted in coke oven workers to evaluate the biological consequences of the exposure of these workers, particularly production of potential genotoxic factors. METHODS: 60 coke oven workers and 40 controls were recruited in the same iron and steel works. Exposure to polycyclic aromatic hydrocarbons (PAHs) was assessed by job and measurement of 1-hydroxypyrene (1OHP) in urine samples. An unscheduled DNA synthesis assay was performed on rat pleural mesothelial cells used as a test system to evaluate the effect of the workers' filtered urine on the DNA repair capacity of rat cells to determine whether DNA damaging agents are present in the urine of these workers. RESULTS: Urinary concentrations of 1OHP ranged from 0.06 to 24.2 (mean (SD) 2.1 (3.6)) mumol/mol creatinine in exposed coke oven workers, and from 0.01 to 0.9 in controls (0.12 (0.15)). These high concentrations in coke oven workers reflected recent exposure to PAHs and were in agreement with the assessment of exposure by job. No significant difference was found between coke oven workers and controls in the DNA repair level of rat cells treated with urine samples. However, the rat cell repair capacity decreased with increasing 1OHP concentrations in the exposed population (r = -0.28, P < 0.05). CONCLUSIONS: As high concentrations of 1OHP were found in the urine of some workers, a more stringent control of exposures to PAHs in the workplace is required. Exposure to PAHs was not associated with a clear cut modification of the urinary excretion of DNA damaging factors in this test, as shown by the absence of increased unscheduled DNA synthesis in rat cells. However, impairment of some repair mechanisms by urinary constituents is suspected.

Adult↗
PubMed1995

[Chronic obstructive bronchopneumopathy after acute inhalation of sulfur anhydride. Apropos of a case].

We report on an acute accidental inhalation of sulfurous anhydride, by a man aged thirty in the course of his work. This intoxication, followed by acute respiratory distress, first showed an improvement, then re-aggravation 26 days after the accident. This episode has not been explained. The patient then developed a chronic obstructive bronchopathy. Ten years of regular observation allows us to maintain that the severe obstructive syndrome which the patient presents has never regressed (FEV1/FVC = 32%), and must be associated with a chronic toxic obstructive bronchopneumopathy.

Accidents, Occupational↗
PubMed1993

Respiratory symptoms, lung function, and pneumoconiosis among self employed dental technicians.

From the registry of self employed workers living in Paris, a group of 105 dental technicians was studied to evaluate occupational exposure, to determine respiratory manifestations, and to investigate immune disturbances. Seventy one dental technicians (age range 43-68: group D), 34 dental technicians younger than 43 or older than 68 (group d), and 68 control workers (age range 43-66: group C) were investigated. The demographic characteristics and the smoking habits of the groups D and C did not differ significantly. The dental technicians often worked alone (43.7%) or in small laboratories without adequate dust control. The mean duration of their exposure was long (group D 34.0 (SD 8.4) years). The prevalence of respiratory symptoms did not differ between groups D and C except for the occurrence of increased cough and phlegm lasting for three weeks or more over the past three years (group D 16.9%, group C 2.9%, p < 0.007). The effect of cigarette smoking on respiratory symptoms and lung function was obvious. All mean values of lung function for dental technicians and controls were within normal limits. Significant decreases in all mean lung function values were found among smokers by comparison with non-smokers, however, and a positive interaction with occupational exposure was established. The x ray films of dental technicians (n = 102, groups D and d) were read independently by four readers and recorded according to the International Labour Office classification of pneumoconioses. The prevalence of small opacities greater than 1/0 was 11.8% with a significant increase with duration of exposure. The prevalence among dental technicians with 30 years or exposure or more was significantly higher (22.2%) than those with less than 30 years (3.5, p < 0.004). The prevalence of autoantibodies (rheumatoid factors, antinuclear antibodies, and antihistone antibodies) was not significantly different in the groups D and C. When positive, autoantibodies only occurred at low concentrations. This finding contrasts with previous reports on the occurrence of autoantibodies and even of connective tissue diseases in dental technicians. In conclusion, the study confirms an increased risk of pneumoconiosis among dental technicians. Moreover, there may be other lung disorders such as impairment of lung function especially in association with cigarette smoking.

Adult↗