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Biomedical subjects

Q T Pham

Publications and source records attributed to Q T Pham.

At least 55 records · Page 3Linked to original sources
PubMed1989

Lung function in adolescents after uncomplicated whooping cough in childhood.

Ventilatory function (forced vital capacity, forced expiratory volume in one second, forced expiratory flows), static lung volumes, phase III slope and closing volume (single-breath nitrogen washout test) were measured in 499 children and adolescents aged 10-16 yrs from a general population sample in North-East France. A history of whooping cough was given by 44 children (22 of each sex); their results were compared to those of the 455 children (215 girls) with a negative history. The only difference between the two groups was a minimal increase in the residual volume/total lung capacity ratio in cases (19.2 +/- 3.1 vs 18.0 +/- 2.9%). We conclude that uncomplicated whooping cough in early childhood did not lead to significant pulmonary function abnormality in this population of children born after 1967.

Adolescent↗
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

Computerized single-breath nitrogen washout in children: variability and reproducibility.

The variability, short-term (1 hour) and long-term (2 weeks) reproducibility of the variables derived from the single-breath N2 test were evaluated in a group of 56 healthy children aged 10 to 16 years with a computerized system. The variability was low for vital capacity and total lung capacity (coefficient of variation less than 3%), moderate for residual volume and phase III N2 slope (9 and 13%) and very high for closing volume (more than 50%). A closing volume could not be identified by the computer algorithm in 18.3% of the trials. The reproducibility of the variables was satisfactory both at 1 hour and at 2 weeks, with the exception of the closing volume, whose increase at 2 weeks seemed to be due to methodological factors. We conclude that reliable results of static lung volumes and phase III N2 slope, but not of closing volume, may be obtained in children by a computerized system in epidemiological studies.

Adolescent↗
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↗
PubMed1987

Risk of lung cancer among iron ore miners: a proportional mortality study of 1,075 deceased miners in Lorraine, France.

A proportional mortality study of 1,075 iron ore miners in Lorraine, France, who died between 1960 and 1976 showed a significant excess of lung cancer mortality (proportionate mortality ratio = 2.25). Moreover, proportionate lung cancer mortality increased with the duration of work underground (proportionate mortality ratio = 4.24 for subjects who worked underground for more than 30 years) and was higher among pneumoconiotic (siderotic) miners (proportionate mortality ratio = 3.85) than among nonpneumoconiotic miners. These results were confirmed by a case-control study nested in the mortality study. Smoking habits could not be estimated retrospectively with sufficient accuracy to be taken into account. Although the proportion of smokers among contemporary iron ore miners is larger than in the French male population, occupational factors may also play a role; radiation exposure can be ruled out because there is no detectable radioactivity in the Lorraine mines, but dust exposure may be considered as an etiologic factor owing to the relationship between siderosis and lung cancer.

Adult↗
PubMed1986

Oral cavity and laryngeal cancers among man-made mineral fiber production workers.

From 1975 to 1984, the incidence of cancer was determined among workers employed in a French man-made mineral fiber (MMMF) production plant. The cohort, including 1 374 fully active or retired men, represented 12 793 person-years. Forty-one patients had cancer, 19 of which were in the upper respiratory and alimentary tract and five of which were lung cancers. The number of lung cancers observed did not significantly differ from that expected [standardized incidence ration (SIR) 0.7]. However the incidence of upper respiratory and alimentary tract cancers was significantly higher (SIR 2.2), especially for those in the larynx (SIR = 2.3), pharynx (SIR 1.4), and buccal cavity (SIR 3.0). The relative risk of cancers in the upper respiratory and alimentary tracts seemed to increase with the length of exposure to glass fibers and exceeded the value of 3.0 for more than 10 years of exposure. This result does not seem to be attributable to an excess of tobacco and/or alcohol consumption. No previous survey of the MMMF industry has shown such a risk, except in Italy. Thus this finding has to be confirmed.

Adult↗
PubMed1986

Tests of small airway dysfunction: their correlation with the "conventional" lung function tests.

"Sensitive" and "conventional" lung function tests were compared in a group of 114 males, aged 35-55 years, including healthy non-smokers, asymptomatic smokers with normal spirometry, and smokers with chronic bronchitis with or without mild airflow limitation. In non-smokers, with the exception of a MEF vs. FEV1 correlation, "sensitive" and "conventional" tests were independent of each other. In asymptomatic smokers the phase III slope and the closing volume were significantly related to FEV1, RV/TLC and CO transfer factor. In smokers with chronic bronchitis all the "sensitive" tests were related to the "conventional" tests (with the exception of the total lung capacity). Hyperinflation and CO transfer impairment suggest that early emphysema may accompany mucus hypersecretion in smokers.

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↗
PubMed1986

[Epidemiology of occupational respiratory diseases].

In the occupational environments air pollutants may be of different natures (chemical, mineral, etc.) and forms (particles, gas, etc.). Except in some acute circumstances the respiratory diseases need several years to develop. These diseases may be specific, caused by a particular pollutant (i.e.: silicosis, asbestos) or non specific (i.e.: chronic bronchitis). Epidemiological studies are well-adapted tools for the acquisition of knowledge and understanding of the pathological processes. They may also lead to efficient preventive action, treatment or compensation. For each of these 3 points (knowledge, understanding, action) one must keep in mind specificities of the respiratory diseases which may be different from one to the other with respect to etiological factors, varieties of disordered structure and function. One also must keep in mind the specificities of the place where the studies will be conducted (large or small factories, professional groups, specific or miscellaneous hazards), the research teams with different skills and competences, the relational problems with the managers, the workers, the unions, the occupational physician, etc. Some particular comments are given about the definition of the disease, the ways of examination methods, the population to be studied and controlled, the evaluation of hazards, the relationships between disease and risk factors.

Bronchitis↗
PubMed1985

A longitudinal study of pulmonary function in coal miners in Lorraine, France.

A longitudinal study of pulmonary function and radiological change has been conducted on 141 nonsmoking coal miners and 256 smoking coal miners from Lorraine, France. At the time of the first examination occasioned by radiological change or shortness of breath, the men averaged between 46.6 years and 50.9 years of age, and they retired approximately 8 years after entering the study. They have been followed for average periods of about 18 years and a mean of five FEV1 observations per man were made over that period. Changes in radiological category have been documented. Average rates of decline of FVC and FEV1 were similar, and varied between -47 ml/yr in nonsmoking miners still alive, to -78 ml/yr in deceased smoking miners. These accelerated rates were similar before and after retirement from the mine.

Age Factors↗
PubMed1985

Lung function and clinical findings in a cross-sectional study of arc welders. An epidemiological study.

An epidemiological, cross-sectional study was conducted in order to assess non-neoplasic effects on the lung due to chronic exposure to arc welding fumes and gases. The study involved 346 arc welders and 214 control workers from a factory producing industrial vehicles. These workers (welders and controls) had never been exposed to asbestos. Respiratory impairments were evaluated by using a standardized questionnaire, a clinical examination, chest radiophotography and several lung function tests (spirometry, bronchial challenge test to acetylcholine, CO transfer tests according to the breath-holding and the steady-state methods, N2 washout test). The only significant differences between the welders overall compared to the controls were a slightly higher bronchial hyper-reactivity to acetylcholine and a lower lung diffusing capacity for CO in the welders. However, non-specific, radiologic abnormalities (reticulation, micronodulation) and obstructive signs were more frequent in the most exposed welders (welding inside tanks) than in welders working in well ventilated workplaces. The nature of the metal welded (mild-steel, stainless steel, aluminium) did not seem to have an influence on respiratory impairments. In the mild-steel welders, respiratory symptoms (dyspnoea, recurrent bronchitis) and obstructive signs were more frequent in the welders using a manual process than in the welders involved with the semi-automatic process (MIG). For all the workers (welders and controls), smoking had a markedly adverse effect on respiratory symptoms and lung function. Moreover, smoking seemed to interact with welding since CO lung transfer was more impaired in smoking welders than in smoking controls.

Adult↗
PubMed1985

[Effect of smoking on the concentration and activity of serum alpha-1 anti-protease according to Pi phenotype].

In an epidemiological study on the respiratory pathology of 1 100 iron miners, the alpha 1 protease inhibitor concentration (alpha 1 Pi) and the elastase inhibitory capacity (EIC) of serum were determined in 97 men with deficient Pi phenotype (73 MS, 24 MZ or S) compared with PiM non deficient men adjusted for age and tobacco consumption. There were differences in alpha 1 Pi concentration and in alpha 1 inhibitory capacity between phenotype groups in agreement with the results of other studies. Smoking produces an increase of serum alpha 1 Pi concentration and EIC in all Pi phenotype groups. This increase is more important (30%) in the MS group than in the others (MZ 20%, M 12%). This effect which appears to be related to smoking intensity does not seem to have a link with an alteration or a modification of the molecular function which is at a rate of 70% in all cases.

Adult↗
PubMed1985

[Computerizing the single-breath nitrogen washout test].

The classical assembly used for the single breath nitrogen washout implies the manipulation of valves by the operator, a perfect coordination of respiratory maneuvers by the subject and a rigid standardization of the interpretation of the tracings by the technicians doing the calculations. We present a computerized analysis of the single breath nitrogen test, based on a microcomputer (Apple II 48K) solving most of the problems above. The opening of the valves is operated by the computer program recorded on disk; the tidal volume and expiratory flow are displayed on the screen on line allowing the subject to comply with the requested limits; the nitrogram is displayed at the end of the test, allowing the technician to explain the errors (if any). The program then goes on computing the slope of phase III, the closing volume, total lung capacity and its subdivisions for each trial, and the average values for two or three trials accepted by the operator. The system worked satisfactorily during a pilot study in healthy adults (variability and reproducibility) and was particularly useful in a field survey of children and adolescents.

Closing Volume↗
PubMed1985

[Effects of incomplete inspiration and previous pulmonary volume history on the nitrogen test].

The effect of incomplete inspiration and of preceding lung volume history on the different parameters of the expired nitrogen curve after inhaling pure oxygen were studied in 12 healthy non-smokers, aged 21 to 35. The equipment used was attached to a mini-computer enabling the regulation of the measurements and the performance of the tests with immediate calculations on the different indices derived from the curve (VC, RV, TLC, delta N2, CV-closing volume, CV/VC). With each subject three measurements were made: measurements in the normal way (N) after incomplete inspiration (I) and finally after 5 forced inspirations and expirations (previous history - P). The procedure (I) gave values of VC and TLC which were lower than those observed with the other methods and the slope of delta N2 and the CV/VC were higher. After the previous lung volume history (P) VC and TLC were significantly higher, the CV/VC ratio was lower (due to the increase of CV). The measurement technique was not influenced either within sessions or between sessions a week apart.

Adult↗