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Q T Pham

Publications and source records attributed to Q T Pham.

At least 19 recordsLinked to original sources
PubMed1999

Age and bronchial hyperresponsiveness are associated with failure to perform the single breath N2 test in a rural female population.

Because some authors have reported high rates of failure in performing the single breath N2 (SBN2) test in rural areas, the present study aimed at evaluating its acceptability in a female population, unfamiliar with lung function testing, in a rural area of northeastern France. Two hundred ninety-eight women from a rural area volunteered for a preventive medicine examination (91.6% of those invited); four of them were excluded for clinical reasons, and six (2%) were unable to perform spirometry. The protocol included completion of a questionnaire, spirometry with a bronchial reactivity test, skin prick test, and the SBN2 test utilizing a computerized assembly. Although failures caused by the apparatus were few (n = 7, 2.4%) 96 of 281 women (34.1%) were unable to produce two valid SBN2 tests in a series of six attempts. Compared with the group who succeeded in the test (n = 185), women who failed were older and had a higher prevalence of bronchial hyperresponsiveness. Logistic regression confirmed the independent association of these two variables with an inability to perform. We conclude that in a female population completely unfamiliar with lung function testing the SBN2 test has a high rate of failure associated with higher age and the presence of bronchial hyperresponsiveness.

Adolescent↗
PubMed1999

Bronchial hyperresponsiveness in farmers: relation to respiratory symptoms, lung function, and atopy.

There is only limited information on the factors associated with nonspecific bronchial hyperresponsiveness (BHR) in farmers. Our purpose was to examine the relationship between BHR and respiratory symptoms, atopy, and abnormalities of lung function in a sample of French farmers. Farmers scheduled for a preventive medicine check-up in northeastern France were examined. Occupational exposure, respiratory symptoms, and work-related symptoms were assessed by questionnaire, sensitization to 34 common and agricultural allergens by skin prick tests, and BHR by the single-dose (1,200 microg) acetylcholine (ACh) challenge test. Data were obtained from 741 farmers (95% of those invited). Seventy-seven subjects (10.3%) had BHR defined as a fall in forced expiratory volume in 1 s (FEV1) >/= 10% after the inhalation of ACh or, for those with a poor lung function, an increase in FEV1 > 10% and > 200 ml after the inhalation of 200 microg of salbutamol. The proportion of asthmalike symptoms, especially wheeze during work, positive skin tests to acarian (storage mites) and cereal dust allergens, and low levels of lung function was significantly greater among reactors than among nonreactors. Stepwise logistic regression analysis showed a significant and independent association between BHR and wheezing during work (OR = 4.99; 95% CI = 2.29-10.89; p = 0.0001) and baseline FEV1 (OR = 1.49; 95% CI = 1.05-2.20; p = 0.026). In conclusion, hyperreactive farmers had significantly more asthmalike symptoms, positive skin tests, and abnormal lung function than normoreactive farmers. Work-related wheeze and low baseline FEV1 were significantly and independently associated with BHR.

Agriculture↗
PubMed1999

Dose-response slope of forced oscillation and forced expiratory parameters in bronchial challenge testing.

In population studies, the provocative dose (PD) of bronchoconstrictor causing a significant decrement in lung function cannot be calculated for most subjects. Dose-response curves for carbachol were examined to determine whether this relationship can be summarized by means of a continuous index likely to be calculable for all subjects, namely the two-point dose response slope (DRS) of mean resistance (Rm) and resistance at 10 Hz (R10) measured by the forced oscillation technique (FOT). Five doses of carbachol (320 microg each) were inhaled by 71 patients referred for investigation of asthma (n=16), chronic cough (n=15), nasal polyposis (n=8), chronic rhinitis (n=8), dyspnoea (n=8), urticaria (n=5), post-anaphylactic shock (n=4) and miscellaneous conditions (n=7). FOT resistance and forced expiratory volume in one second (FEV1) were measured in close succession. The PD of carbachol leading to a fall in FEV1 > or = 20% (PD20) or a rise in Rm or R10 > or = 47% (PD47,Rm and PD47,R10) were calculated by interpolation. DRS for FEV1 (DRSFEV1), Rm (DRSRm) and R10 (DRSR10) were obtained as the percentage change at last dose divided by the total dose of carbachol. The sensitivity (Se) and specificity (Sp) of DRSRm, DRS10 delta%Rm and delta%R10 in detecting spirometric bronchial hyperresponsiveness (BHR, fall in FEV1 > or = 20%) were assessed by receiver operating characteristic (ROC) curves. There were 23 (32%) "spirometric" reactors. PD20 correlated strongly with DRSFEV1 (r=-0.962; p=0.0001); PD47,Rm correlated significantly with DRSRm (r=-0.648; p=0.0001) and PD47,R10 with DRSR10 (r=-0.552; p=0.0001). DRSFEV1 correlated significantly with both DRSRm (r=0.700; p=0.0001) and DRSR10 (r=0.784; p=0.0001). The Se and Sp of the various FOT indices to correctly detect spirometric BHR were as follows: DRSRm: Se=91.3%, Sp=81.2%; DRSR10: Se=91.3%, Sp=95.8%; delta%Rm: Se=86.9%, Sp=52.1%; and delta%R10: Se=91.3%, Sp=58.3%. Dose-response slopes of indices of forced oscillation technique resistance, especially the dose-response slope of resistance at 10Hz are proposed as simple quantitative indices of bronchial responsiveness which can be calculated for all subjects and that may be useful in occupational epidemiology.

Adult↗
PubMed1998

Relationship of serum neutral endopeptidase E.C.3.4.24.11 activity to alcohol consumption.

Neutral endopeptidase (NEP) is an ubiquitous enzyme that inactivates numerous endogenous peptides in the brain, kidney, and lung in vivo. The origin of the circulating soluble form and its determinants are largely unknown. The relationships of smoking habits and alcohol consumption to serum NEP activity have been explored in a longitudinal epidemiological study conducted in 204 Lorraine coal miners. At both surveys, 4 years apart, NEP activity was significantly related to alcohol consumption (in grams/day) reported by questionnaire, with correlation coefficients of 0.26 (p = 0.001) in 1990 and 0.23 (p = 0.001) in 1994. The correlations of gamma-glutamyltransferase to NEP activity were even stronger with correlation coefficients of 0.71 (p = 0.0001) in 1990 and 0.79 (p = 0.0001) in 1994. Longitudinally, the change in NEP activity between the first and the second surveys was significantly correlated with change in alcohol consumption (r = to 0.18, p = 0.02) and with change in gamma-glutamyltransferase level (r = 0.60, p = 0.0001). Serum NEP activity was unrelated to smoking habits. Results support the hypothesis of a causal role of alcohol on serum NEP activity.

Adult↗
PubMed1998

Relations between occupational exposure to coal mine dusts, erythrocyte catalase and Cu++/Zn++ superoxide dismutase activities, and the severity of coal workers' pneumoconiosis.

OBJECTIVES: To better understand the relations between occupational exposure, blood antioxidant enzyme activities, total plasma antioxidant concentration, and the severity of coal workers' pneumoconiosis (CWP). METHODS: Blood samples were obtained from miners without CWP exposed to low dust concentrations for > or = 4 years at the time of the study (n = 105), or exposed to high dust concentrations for > or = 14 years at the time of the study (n = 58), and from retired miners with CWP (n = 19). Miners without CWP were classified into three subgroups according to their estimated cumulative exposure to dust. Chest x ray films were obtained for each miner. Miners were classified in five subgroups according to their International Labour Organisation (ILO) profusion grades. Univariate tests were completed by multiple linear regression analyses. RESULTS: The estimated cumulative exposure to dust was strongly positively related to erythrocyte catalase activity and strongly negatively related to Cu++/Zn++ SOD activity only in miners exposed to high dust concentrations for > or = 14 years at the time of the study (F tests p = 0.006 and p = 0.004 respectively). Moreover, catalase activity was strongly related to the severity of CWP expressed as five subgroups of ILO profusion grades (F test p = 0.003); the greatest difference in the mean values was found between the group of 1/1 to 1/2 ILO profusion grades and the group of 2/1 to 3/3 ILO profusion grades. CONCLUSION: These results are in good agreement with the hypothesis that production of reactive oxygen species may be an important event in the exposure to coal mine dusts and the severity of CWP. Erythrocyte catalase and Cu++/Zn++ SOD activities are more closely related to recent exposure to high dust concentrations than to cumulative exposure, and could be considered as biological markers of exposure rather than as markers of early adverse biological effect.

Adult↗
PubMed1998

Can the evolution to pneumoconiosis be suspected in coal miners? A longitudinal study.

To assess whether the evolution to pneumoconiosis may be suspected in coal miners, we conducted a 4-yr longitudinal study of 80 dust-exposed miners with chest X-ray findings classified 0/1 or 1/0 according to the International Labor Organization (ILO) classification (exposed to coal mine dust, suspected of pneumoconiosis [ES group]) and two control groups having normal X-rays. The first of these latter two groups included 80 miners with similar exposure to that of the first group (exposure with normal X-rays [EN]), whereas the second group consisted of markedly less exposed miners (no exposure with normal X-rays [NN]). The protocol comprised a questionnaire on respiratory symptoms and smoking, assessment of cumulative coal-mine-dust exposure, X-rays, computed tomographic (CT) scans, and lung-function tests. The study was conducted in 1990 and 1994 by the same medical team. At the end of the follow-up, 24 members of the ES group had worsened X-ray findings, and 10 of them had X-ray findings classified as 1/1 or greater. In the EN and NN groups, six and one subjects, respectively, had worsened X-ray findings. At the first examination, subjects who developed pneumoconiosis had significantly lower values for FEV1/FVC ratio, maximum midexpiratory flow (MMEF), and maximal forced expiratory flow at 25% of vital capacity (FEF25%), and higher CT-scan micronodule scores. This latter score and FEF25% were significantly associated with the evolution to pneumoconiosis in the ES group, and scanner micronodule score and MMEF were significantly associated with this in all three groups combined. Worsening findings on X-ray and change to pneumoconiosis must be controlled in coal miners. The findings in this study offer the possibility of identifying miners who especially need follow-up and monitoring.

Adult↗
PubMed1997

The single-breath nitrogen test in coal miners: factors associated with failure to perform.

The single-breath nitrogen washout (SBN2) test was used, along with spirometry, in the baseline examination of a longitudinal study in a cohort of active coal miners from North-eastern France. The procedure was computerized, allowing the technician to coach and encourage the subject, and excluding computation errors. While all miners performed satisfactory spirometry, a significant number were unable to meet the National Heart and Lung Institute recommendation concerning a 10% agreement of vital capacities. When the limits were set at +/-12%, 57 miners (24.2%) were still classified as failing to perform. When compared to those who succeeded, those failing proved to be significantly older, had more cumulated dust exposure, a higher prevalence of chronic cough and sputum, and a trend for more micronodulation on the chest radiographs. The ventilatory function did not differ between the two groups. These results confirm previous data on spirometric test failure concerning older age and respiratory symptoms, extending them to the SBN2 test. The present study further indicates that dust exposure and roentgenologic pneumoconiosis nodulation are associated with failure to perform the SBN2 test.

Adult↗
PubMed1997

Relationship of serum elastin peptide level to single breath transfer factor for carbon monoxide in French coal miners.

BACKGROUND: Clinical and epidemiological studies have given discordant results on the usefulness of the level of circulating elastin peptide (EP), a potential marker of both elastin destruction (a key phenomenon in pulmonary emphysema) and neosynthesis, for assessing structural changes in the lung extracellular matrix. The aim of the present study was to explore the relationship between levels of EP and forced expiratory volume in one second (FEV1) and single breath transfer factor for carbon monoxide (TLCO and KCO) in coal miners. METHODS: The study population comprised 227 working coal miners aged 34-50 years consisting of 75 miners heavily exposed to underground coal dust with pulmonary radiographs classified as 0/1 or 1/0 by the International Labour Office classification, 75 exposed miners with radiographs classified as normal (0/0), and 77 miners slightly exposed to coal dust with normal radiographs. The subjects answered a standardised questionnaire and performed spirometric tests and a carbon monoxide (CO) transfer test. RESULTS: No association was observed between EP levels and % predicted FEV1 (or FEV1/FVC). The level of EP increased significantly with decreased % predicted TLCO (r = -0.20). Miners in the lowest % predicted KCO quintile had higher EP levels than the rest (3.28 (1.37) vs 2.47 (1.16)). A significantly lower EP level was observed in miners with radiographs classified as 1/0 or 0/1, especially in those with round opacities, compared with miners with a normal radiograph, and in current smokers compared with the rest. CONCLUSIONS: The results of this study suggest that the level of EP may reflect some remodelling activity in emphysema and lung fibrosis.

Adult↗
PubMed1996

Decrease in selenium status in relation to coal dust exposure.

Selenium (Se) plasma levels were studied in 222 coal miners to assess whether selenium is decreased in relation to coal dust exposure, taking age, alcohol, and tobacco consumption into account. Selenium levels decreased significantly with age and current tobacco consumption, among miners aged 34-50. Long-term and current exposure to coal dust were studied. The lowest Se values were observed for those with both long-term and current exposure (60.2 ng/ml), the highest for those never or slightly exposed (64.1 ng/ml); those with long-term exposure not currently exposed fell in an intermediate position (61.3 ng/ml). No relation was observed with alcohol consumption. The association of coal dust with low selenium remained significant after adjustment for age and smoking.

Adult↗
PubMed1996

Computerized single-breath nitrogen washout: predicted values in a rural French community.

Comparative manual and computer measurements of the alveolar N2 slope and closing volumes have indicated systematic differences. When a computerized system is used in field surveys, predicted values are to be obtained under the same conditions. Therefore, we measured the alveolar nitrogen slope (phase III, PIII), closing volume (CV), and closing capacity (CC) from single-breath N2 washout maneuvers in 158 healthy subjects (68 females), ages 21 to 64 years, from a rural community living in a nonpolluted area of northeast France. PIII, the CV to vital capacity ratio (CV:VC, %), and the CC to the total lung capacity ratio (CC:TLC, %) were regressed against age, height, weight, and the body mass index (BMI, kg/m2) and prediction equations with 95% confidence intervals were computed. PIII increased with age in both sexes and tended to decrease with height in males (r = -0.19, p = .08). The CV:VC and CC:TLC ratios depended on age and, in males, increased with the BMI. Despite accepting a 15% difference between the test VC and the spirometric VC, only 46.3% of asymptomatic nonsmokers produced a valid single-breath nitrogen washout (SBN2) test. This high failure rate limits the usefulness of the test for epidemiologic purposes when older populations "naive" to pulmonary function testing are studied under field-survey conditions.

Adolescent↗
PubMed1996

Associations of blood group-related antigens to FEV1, wheezing, and asthma.

Discordant results have been observed regarding the associations of chronic obstructive pulmonary diseases with secretor, Lewis, and ABO histo-blood groups, which are defined by glycosyltransferases. These enzymes build up oligosaccharide structures that play a role in the adhesion of environmental factors to epithelial cells. The objectives of the present study were to assess the role of all three systems, Lewis (Le), salivary ABH secretor (Se), and red cell blood group ABO, on lung function, wheezing, and asthma in a cohort of 228 coal miners studied cross-sectionally, considering the potential modifying effect of environmental factors on these associations. Asthma was significantly related to nonsecretor phenotype. Significantly lower lung function and higher prevalences of wheezing and asthma were observed in Lewis-negative or nonsecretor subjects of blood group O. Very low lung function values were observed in the small group of Lewis-negative nonsecretors who lack both Le and Se controlled fucoses (1% of Caucasians). Lewis-positive, salivary ABH secretors who have these two fucoses represent 70% of Caucasians. Among these subjects, lower lung function was observed in blood group A, and in a lesser extent in blood group B, i.e., with terminal alpha GaINAc or alpha Gal respectively, than in blood group O subjects. ABO, Lewis, and secretor phenotypes did not account for the potential genetic heterogeneity of subjects toward smoking, but alcohol consumption appeared to exert a protective effect on lung function in Lewis-negative subjects (10% of Caucasians). If confirmed in other populations, the magnitude of the effects observed regarding low lung function in Lewis-negative ABH nonsecretors, and the protective effect of Lewis negative on the deleterious effect of alcohol, may be of clinical importance. Further studies of the combined effects of various histo-blood group genetic systems seem worthwhile, particularly for airflow limitation, wheezing, and asthma, possibly with reference to susceptibility to infectious agents.

ABO Blood-Group System↗
PubMed1996

Lack of a relationship of elastin peptide level to emphysema assessed by CT scans.

Clinical reports suggest that peptide (EP) concentration may be used as a subclinical marker of pulmonary emphysema. This hypothesis was tested in a clinical study by comparing EP concentration in male emphysematous patients with the level in two control groups, and by exploring the relation of elastin peptide level to high-resolution computed tomography (HRCT) scan emphysema score among emphysematous patients. Serum EP level was determined among male emphysematous patients with at least 20% of emphysema (n = 27) and in two populations of male workers, drawn from epidemiologic studies (227 coal miners and 310 policemen). No difference in elastin peptide concentration was observed between emphysematous patients and control subjects (mean +/- SD = 2.39 +/- 1.18 micrograms/ml in patients versus 2.55 +/- 1.34 micrograms/ml in policemen and 2.59 +/- 1.20 micrograms/ml in coal miners). The correlation of elastin peptide concentration with percentage of pulmonary emphysema was negative and of borderline significance (r = -0.36; p = 0.06). These results cast doubts on the usefulness of elastin peptide level as a predictive marker of pulmonary emphysema.

Adult↗
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↗
PubMed1994

[Estimation of static lung volumes by nitrogen washout method. Single breath of oxygen].

Total lung capacity (TLC) and residual volume (RV) estimations were obtained from single-breath nitrogen washouts in 96 male and 77 female healthy never-smokers with normal spirometry from a non-polluted rural area in north-east France. TLC depended on height (both sexes) and diminished slightly with age in males, with the body-mass index (kg/m2) in females. RV increased with age in both sexes and with weight in males. The RV/TLC ratio was related only to age. When compared with values obtained using multiple-breath helium dilution, our results yielded lower predicted values. The test depends heavily on the subject's co-operation, and errors are frequent if a standard procedure is not observed. This method cannot thus be recommended for routine use in patients with respiratory diseases.

Adult↗
PubMed1994

Measurement of respiratory impedance by forced oscillation: comparison of the standard and head generator methods.

Physiological and clinical studies have shown that the standard method of measuring respiratory impedance by forced oscillation leads to less efficient control of the upper airway shunt effect than the head generator method. To test the effects of these two techniques in epidemiological studies, we compared, in a sample of 73 French agricultural workers, the values obtained with each method for five forced oscillation parameters: resistance, frequency dependence of resistance, inertance, compliance and resonant frequency. For these comparisons, subjects were classified according to four respiratory status factors: smoking status, cough, expectoration and airway obstruction assessed from the maximum expiratory flow volume curve. Logistic regression models using the set of four forced oscillation parameters (excluding resonant frequency, which is derived from compliance and inertance) were then used to analyse the ability of each method to classify the subjects in each group. Significant differences between the two methods were observed for the mean values obtained for all five parameters. However, when each parameter was considered separately, the correlations between the values for each method were significant. Each method possessed the necessary ability to separate subjects into our group classification, but the significant relationships were not always found for the same parameters. Finally, logistic regression models showed that the two methods led to almost the same classification of the subjects. According to our results, the standard method of applying forced oscillation at the mouth seems an acceptable device for measuring respiratory impedance for epidemiological purposes.

Airway Obstruction↗
PubMed1993

Variability of the computerized single-breath nitrogen washout test in healthy adults. Results from a field survey in a French rural area.

Within-subject (difference between paired tests, or coefficient of variation [c. var.] of three consecutive measurements) and between-subjects (standard deviation of the mean group) variability were assessed for the variables derived from the single-breath nitrogen (SBN2) test in a group of healthy, asymptomatic subjects (n = 289) aged 20-64 years, from a rural area in North-East France. Duplicate measurements in 99 subjects showed excellent agreement between the two attempts (correlation coefficients between 0.94 and 0.98) for static lung volumes and the alveolar N2 slope (PIII); closing volumes (CV) were more variable (r = 0.77 for absolute value, 0.79 for % VC) while closing capacities (CC) were in intermediate position (r = 0.86 for absolute value, and 0.88 for % TLC). The variability of three consecutive measures in 190 subjects showed the coefficients of variation to be low for static volumes and closing capacity (2.4-7.4%) and higher for PIII (15.1%) and CV or CV/VC (18.2 and 17.8%). The analysis of variance did not detect significant differences between the three sets of measurements, with the exception of a progressive increase of vital capacity (VC), and decrease in residual volume (RV) from test 1 to test 3, the total lung capacity being the same. Variability was uninfluenced by age or sex, except a higher c. var. for female VC as compared to males (2.8 vs. 2.2%, P = 0.02) and a higher variability of TLC (2.9 vs. 2.3%, P = 0.03) and VC (2.8 vs. 1.9%, P = 0.003) in people older than 40 years as opposed to those younger than 40 years.

Adolescent↗