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Biomedical subjects

N Chau

Publications and source records attributed to N Chau.

At least 19 recordsLinked to original sources
PubMed1995

Oral health in adolescents from a small French town.

In France, caries are more prevalent in rural areas than in large cities. This study analyzed the relationship between number of oral health indices and some known risk factors (toothbrushing, sugar consumption, saliva components) and sociodemographic factors in adolescents from a small town. The sample included 112 children aged 12-14 in the north-east of France. School marks was found to be better linked with dental caries indices than the socio-occupational category of parents: gingival index (GI), DMFS, DMFT and caries severity (CS) significantly increased with decreasing school marks; oral plaque was related to socio-occupational of parents. The analysis using the regression method showed that the variance explained by the various factors studied was modest (between 23 and 30%) for GI, initial caries sites (IS), DS, DMFS, DMFT and CS, and was small for plaque (5%) and calculus (3%). This would be due in part to the wide dispersion of these indices. The sex had a non-significant regression coefficient for all oral health indices investigated. For GI, only mutans streptococci (MS) and plaque had a significant regression coefficient. Calculus was explained by any factor considered. Only MS had a significant part in plaque. IS was explained by MS, toothbrushing and age. For DS, only toothbrushing, MS and sweet drinks during meals had a significant part. DMFS and DMFT were explained only by MS and age. CS was explained by MS, age, salivary buffer pH, salivary flow rate, and toothbrushing.

Adolescent↗
PubMed1995

Forced oscillation technique (FOT): a new tool for epidemiology of occupational lung diseases?

The aim of this study was to evaluate the usefulness of the forced oscillation technique (FOT) in the assessment of occupation-related airway changes. The forced oscillation technique and conventional lung function tests were applied in 80 underground coalface workers, aged 35-48 yrs, with chest roentgenogram films classified 0/1 or 1/0 according to the International Labour Office (ILO) classification (G group), and two control groups matched for age and smoking habits. The first control group, was made up of face-workers having normal chest radiographs, whilst the second comprised underground non-face-workers with normal chest radiographs. Spirometric, plethysmographic and transfer factor of the lungs for carbon monoxide single-breath (TL,CO,sb) indices revealed no significant differences between the three groups. As regards the forced oscillation technique, a higher value of resistance/frequency slope (Pa.L-1.s2) was found in the G group compared with the control groups; 2.11 vs 1.06 in the face-workers, and 1.58 in the underground workers. In all three groups, the forced oscillation technique indices (mean resistance (R), resistance at zero frequency (RO), resistance/frequency slope (S), and resonant frequency (fo)) were found to be higher in subjects having a decreased forced expiratory volume in one second (FEV1) (< or = 90% predicted) or a mildly obstructive pattern of ventilatory function, even though this did not reach statistical significance in each of the groups. These findings together with the feasibility and acceptability of the forced oscillation technique would suggest that it may be a suitable tool for epidemiological studies of occupational respiratory diseases.

Adult↗
PubMed1994

[Respiratory symptoms and function of coal miners presenting radiological pulmonary abnormalities].

Respiratory symptoms and lung function of 80 coal workers suspected of pneumoconiosis (pulmonary X-rays classified 0/1 or 1/0 according to International Labour Organisation classification) who worked for at least 10 years at face work (Ts) were studied in comparison with two control groups matched by age (+/- 2 years), height (+/- 5 cm), weight (+/- 10 kg) and smoking habits: the Tn group constituted by 80 coal workers who worked for at least 10 years at face work with normal pulmonary X-rays, and the HTn group constituted by 80 underground miners who worked mainly out of face work with normal pulmonary X-rays. The frequencies of cough, expectoration, chronic bronchitis or dyspnoea were significantly higher in Ts group than in the two others. The one-second forced expiratory volume to vital capacity ratio (FEV1/VC) was lower, closing volume to vital capacity (CV/VC) or to total lung capacity ratios (CV/TLC) were higher in Ts group than in the control groups. Unexpectedly, vital capacity (VC), one-second forced expiratory volume (FEV1), total lung capacity (TLC), compliance, diffusing capacity (DLCO) referred to alveolar volume (VA) were higher. In Ts group, the small rounded opacities were noted in the top part of the lung (56.9%), the irregular ones were distributed on the entire lung (65.5%). There were no relation between the category of small opacities and respiratory symptoms or lung function.

Adult↗
PubMed1992

Morbidity in retired coke oven plant workers.

The effect of past occupational exposure on morbidity was studied in 354 coke oven workers in Lorraine Collieries (France) who retired between 1963 and 1982, and were still alive in 1988; 96% of them participated in this study. Occupational exposure to respiratory hazards during the working life was retraced for each subject. No significant association between the occupational exposure and the frequency of ischemic cardiopathies, arterial hypertension, gastro-duodenal ulcers, and respiratory symptoms was revealed. However, subjects who had worked on the Ovens, in the Workshops, and in the Byproducts showed a prevalence of arterial hypertension significantly higher than the non- or slightly exposed subjects. The healthy worker effect phenomenon, the exclusion of deceased subjects, and the small size of this retiree population may conceal possible differences between exposure groups.

Age Factors↗
PubMed1992

Iron miners--a ten year follow-up.

1167 workers of Lorraine (France) iron mines, a random sample of 5600 workers aged 35 to 55 years, at work in 1975 constituted the initial cohort that was examined twice at 5-year intervals after the first examination. A questionnaire on respiratory symptoms and smoking habits (MRC questionnaire) plus questions on the work history of each participant was completed, vital capacity (VC), forced expiratory volume in one second (FEV1.0), residual volume (RV) and fractional uptake of CO (FuCO) were measured at the first examination and repeated five and ten years later. At the end of the ten year follow-up, 522 subjects were re-examined, 186 were lost to follow-up, 328 answered a mail questionnaire, and 111 had died. The total number of deaths was not different from that of the general population, but for lung cancer the standardized mortality ratio (SMR) was significantly increased (SMR = 3.7). For the miners re-examined, frequency of bronchitis and decrease of functional tests were more related to age and smoking habits than to occupation.

Adult↗
PubMed1992

Lung function in retired coke oven plant workers.

Lung function was studied in 354 coke oven plant workers in the Lorraine collieries (Houillères du Bassin de Lorraine, France) who retired between 1963 and 1982 and were still alive on 1 January 1988. A spirometric examination was performed on 68.4% of them in the occupational health service. Occupational exposure to respiratory hazards throughout their career was retraced for each subject. No adverse effect of occupational exposure on ventilatory function was found. Ventilatory function was, however negatively linked with smoking and with the presence of a respiratory symptom or discrete abnormalities visible on pulmonary x ray films. The functional values were mostly slightly lower than predicted values and the most reduced index was the mean expiratory flow, FEF25-75%. The decrease in forced expiratory volume in one second (FEV1) was often parallel to that in forced vital capacity (FVC), but it was more pronounced for subjects who had worked underground, for smokers of more than 30 pack-years, and for subjects having a respiratory symptom. Pulmonary function indices were probably overestimated because of the exclusion of deceased subjects and the bias of the participants.

Aged↗
PubMed1991

[Skin sensitivity to respiratory allergens in agricultural workers and wage-earners].

Prick tests were performed with "pneumallergerns" (mites, cereal dusts, animal dander, pollens, moulds--totalling 35 allergens) among 742 agricultural workers of the Meuse department (North East of France) as part of an epidemiological study on respiratory and immuno-allergological problems. Among those with positive skin tests, 47.9% had positive skin tests for mites, 22.4% for cereal dusts, 10.7% for animals, 12.7% for pollens and 7.8% for moulds. Polysensitization was frequent (19.5% of the population). When the skin test was positive for main house dust mites it frequently was positive for storage mites, too. Among vegetal dusts sensitization, soy bean allergy yielded the highest frequency (6.5%). As for animal sensitization, cow dander was the most frequently observed positive test. Sensitization to pollens and moulds was comparatively rare. This study shows the large frequency and diversity of "latent allergy" to pneumallergens among agricultural workers.

Agriculture↗
PubMed1991

Prospective mortality study among iron miners.

A prospective mortality study was conducted over a period of 5 years on a group of 13,801 iron miners, who were alive on January 1, 1982. During this 5-year period, 1813 deaths were registered. For 1222 (67.4%), the cause of death and work history are known. For 135 (7.4%), the cause of death is known, but not the work history. For 455 (25.1%), the cause of death is unknown. Proportional mortality ratio (PMR) is significantly higher than 1 for lung cancer (PMR = 2.51, p less than 0.001) and for stomach cancer (PMR = 2.31, p less than 0.001). The results are discussed in regard to occupational risks that result in these two kinds of increased mortality rates, and the hypothesis of redox activity on the surface of dust particles is advanced as a common denominator.

Adult↗
PubMed1989

[Congenital malformations and socio-occupational status].

A case-control study was conducted in a maternity hospital, in order to look for the relationships between the occurrence of birthdefects and the socio-occupational status of the parents. Cases were 189 new-born children with one or several congenital malformations diagnosed at birth or within the first 8 days of the life. Birthdefects were listed according to the British Paediatric Association classification of diseases. Controls were 5,896 new-born children without any congenital malformation detected within the first 8 days of life. Cases and controls were all children born in the same maternity hospital, between 1980 and 1983. The socio-occupational status (INSEE classification) of the parents of cases and controls was ascertained within the first trimester of the pregnancy, before a possible congenital malformation was known. In order to look for the relationships between the socio-occupational status of the parents and the occurrence of birthdefects, we compared the proportions, in each of the socio-occupational classes, of the fathers and of the mothers of cases and controls. These comparisons (for all birthdefects together and for the most frequent ones) were tested using the chi-square test, when the expected number was greater than 5, and the Fischer's test, when it was equal to, or lower than 5. The incidence rate of birthdefects in this sample was 3,1%. Their distribution according to the types of malformations did not differ from that observed in 1982 among the new-borns in Paris. There was no significant difference between the parents of cases and controls, for: age, degree of instruction, ethnic origin, marital status.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

[Respiratory health of children and atmospheric pollution. I. Respiratory symptoms].

The impact on the respiratory system of complex industrial pollution (dust, sulphur dioxide, nitrogen oxides, hydrocarbons) was assessed by an analytical epidemiological study in a population of school children in the northeast of France. The parents of 375 children aged from 9-12 (middle school course 1 and 2) from the polluted zone and 523 children of the same age in a neighboring zone which was not polluted have filled in standardised questionnaires (respiratory symptoms, previous infections and allergies, frequency of infection in infancy; tobacco habits, professional and educational attainments of the parents, domestic environment). In the exposed children the majority of respiratory symptoms were more frequent (e.g., respiratory sounds in the boys, 15.6% against 7.9% p less than 0.01) and the absenteeism from school was more numerous (66.9% against 59.1% p less than 0.01). However, the interpretation of the results had to take into account the existence of confusing factors: parental smoking habits and the use of coal fires increased the prevalence of symptoms in the polluted zone, whereas a less crowded population worked in the inverse direction; likewise the educational level of the parents was higher in the polluted zone. After adjusting for these confusing factors, the frequency of rhinitis and absenteeism from school was significantly higher in exposed children.

Air Pollution↗
PubMed1989

[Respiratory health of children and atmospheric pollution. II. Ventilatory function].

Respiratory function (forced vital capacity-FVC; forced expired volume in one second-FEV1; maximal mid-expiratory flow-DEMM; peak flow-DP; maximal expiratory flow at 75-50-25% of vital capacity CV-DEMx) was studied in children of comparable age, sex and height (9 to 12 years) in a polluted zone (the exposed group n = 223) and a neighboring non-polluted zone (the control group n = 211) in the north of Lorraine. There was no significant difference in ventilatory function between the two groups. Amongst other factors capable of influencing the ventilatory function in the children we found an influence of parental smoking habits (particularly the mothers) identifiable in the non-exposed zone, above all in boys. A sub-segment analysis identified that in the absence of parental smoking, there was a negative influence of open coal fires. The discordance between the results of the measures of respiratory function and the prevalence of different respiratory symptoms, of acute infections and absenteeism from school, is probably explained by the interference of other factors which were not controlled in this study (e.g., ethnic factors and physical activity) and by the moderate level of the pollution; an over-reporting of respiratory symptoms by parents in the exposed zone could not be excluded.

Air Pollution↗
PubMed1988

Pulmonary function following mild respiratory tract infections ("common cold") in teenagers.

Ventilatory function--forced vital capacity (VC)--forced expiratory volume (in 1-sec forced expiratory flows) static lung volumes, closing volume, and phase III slope (single-breath N2 test) were compared in 94 children with and 436 children without a history of recent mild acute respiratory infection. Their age ranged from 10 to 16 years; subjects with symptoms on the day of the study were excluded. We found no difference in lung function between the two groups, with the exception of a slight (inconsistently significant) increase in closing volume (CV) and the CV/VC ratio. Although the influence of a persistent increase in interstitial lung pressure leading to early small airways closure cannot be ruled out, this isolated functional abnormality probably represents a spurious positive result, arising by chance when a large number of statistical tests are done.

Acute Disease↗
PubMed1988

Respiratory symptoms and pulmonary function in 871 miners according to Pi phenotype: a longitudinal study.

Pi phenotype was determined and alpha 1 protease inhibitor (alpha 1 Pi) was measured in 871 iron-ore miners examined twice at five years interval. A questionnaire on respiratory symptoms was administered and lung function tests: spirometry (VC, FEV1.0), measurements of the residual volume (RV/TLC) and of the CO diffusion (FuCO), were carried out by the same medical and technical team, using the same apparatus. There were no differences in age, length of employment or smoking habits among the three Pi Phenotype groups: M (90.03%), MS (7.1%), MZ (2.8%). The prevalence of clinical symptoms at the initial survey and the incidence of symptoms between the 2 surveys were not related to Pi Phenotype groups. However a significantly steeper decline of FEV1.0/VC was observed in the alpha 1 Pi partially deficient groups MS and MZ (-3.9%) compared with the non-deficient group (-1.8%). No significant difference was observed for VC, RV/TLC and FuCO. This finding suggests that an intermediate deficiency of alpha 1 Pi may be related to a slight but statistically significant impairment of a lung function in occupational conditions.

Adult↗
PubMed1988

Respiratory symptoms or signs on the day of the study alter pulmonary function in teenagers.

Pulmonary function variables (forced expiratory flows and vital capacity, static lung volume, alveolar N2 slope, closing volume and closing capacity) were compared in a group of 10-16 year old children with (n = 65) and without (n = 440) symptoms or signs of mild acute respiratory infection ('common cold'). Symptomatic children had a significant impairment of forced expiratory vital capacity and flows, with no change in static volumes, alveolar N2 slopes and closing volumes. The effect was present only in boys (in whom RV/TLC and phase III slope were borderline abnormal), was more evident in older children (13 to 16 years) and was independent of the smoking habits or the presence of chronic respiratory symptoms. The results are in favour of a predominant involvement of upper airways, but signs of lower airways dysfunction are present in boys and in children 13 to 16 years old.

Acute Disease↗
PubMed1987

Mortality due to respiratory cancers in the coke oven plants of the Lorraine coalmining industry (Houillères du Bassin de Lorraine).

The main activity of the Houillères du Bassin de Lorraine (Lorraine Collieries), employing 23,000 operatives and executives, is coalmining. The coke production is carried out by two coke oven plants with a workforce of respectively 747 and 552 workers. The coal coking process entails the emission of noxious products such as polycyclic aromatic hydrocarbons (PAH) from the ovens. The influence of occupational exposure on mortality due to respiratory cancers, and particularly to lung and upper respiratory and alimentary tracts cancer, was investigated among a cohort of 534 male workers from the two coke oven plants who had retired from work between 1963 and 1982. The job history of each subject has been precisely reconstructed by indicating the duration of exposure on the ovens, close to the ovens, and in maintenance occupations. The cohort mortality has been analysed according to the method of indirect standardisation with reference to the French male population and by a case-control study concerning the consumption of tobacco per cohort. The mortality due to lung cancer is 2.51 times higher than expected. This excess of mortality differs, but not significantly, between the two coke oven plants (standardised mortality ratio equals 3.05 and 1.75 respectively). It is not significantly higher among subjects exposed for more than five years, directly exposed on the ovens or working near the ovens or at maintenance occupations on the ovens (SMR = 2.78), than among those exposed for less than five years (SMR = 2.35) or those not exposed at all. Even taking into account the excess of mortality due to lung cancers in the Moselle district (1.6 time that of France), the excess of lung cancers does not seem to be explained by the regional factor, or by tobacco and alcohol consumption. Although no significant relation was offered between lung cancer and the duration of exposure to PAH, even when taking smoking habits into account, the carcinogenic role of occupational nuisances cannot be excluded.

Age Factors↗
PubMed1987

["Physiologic" aging in 5 years of pulmonary function in 140 iron miners].

Ageing of the lung function in 5 years was studied in a group of 140 iron-ore miners, aged initially from 36 to 55 years. These men had no respiratory symptom and no pulmonary radiological abnormality. The sample was stratified on age and smoking. These factors were studied by a two-way analysis of variance. Lung function testing was performed twice, at 5 years of interval, in the same conditions. It consisted in: spirometry (for measuring FVC, FEV1, FEV1/FVC); a bronchial challenge test with acetylcholine (measurement of the fall of FEV1 after the test); measurement of total lung capacity (TLC) and residual volume (RV) by the open-circuit helium dilution method, and measurement of the transfer factor of the lung for CO, by the steady-state method (TCO/V). The only indices, whose values significantly changed in 5 years were: FVC, FEV1 and TCO/V. Their decrease rate did not appear to be significantly linked to age nor to smoking. According to these results, it seems that the decline of the pulmonary function is relatively constant during the middle period of life and that it is not strongly influenced by smoking, but only among subjects who remain without any respiratory symptom.

Adult↗
PubMed1986

A longitudinal study of symptoms and respiratory function tests in iron miners.

A first survey has been conducted on 1179 iron-ore mine workers, 35-55 years old, who were randomly selected from 5900 at work with normal chest roentgenograms. Five years later, 871 of them were re-examined. Both surveys included a standard respiratory symptoms questionnaire (British MRC), a physical examination of the chest, and measurement of pulmonary function (vital capacity - VC; forced expiratory volume during 1 s - FEV1.0; residual volume - R.V. by helium dilution: carbon monoxide uptake - FuCO by the steady-state method). Both surveys were done by the same research team under identical conditions, using the same equipment. The mine technical services determined the dust and noxious gas concentrations at work places. No evidence of worsening of respiratory health status was observed overall. Symptoms of chronic bronchitis and asthma were recorded with a similar prevalence in both surveys; the decline in lung function was minimal for the total sample. However, our aim was to compare changes that were observed in groups differing by work place (surface or underground) or by activity (active or retired). Analysis showed that development of respiratory symptoms was more frequent and decline in lung function accelerated in the 5-year interval among underground workers who were still active as compared to those retired. In all subgroups (surface or underground workers, active or retired), decline of lung function values was more marked in smokers compared to non-smokers.

Adult↗