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Biomedical subjects

S Vedal

Publications and source records attributed to S Vedal.

At least 19 recordsLinked to original sources
PubMed1995

Determinants of airway smooth muscle shortening in excised canine lobes.

There is marked heterogeneity of airway narrowing in intraparenchymal airways in response to bronchoconstricting stimuli. We hypothesized that this heterogeneity results from variations in the structure of the airway wall. Freshly excised dog lung lobes were inflated to transpulmonary pressures (PL) of between 5 and 15 cmH2O, and an aerosol containing a high concentration of carbachol was administered. The lobes were fixed and processed for light-microscopic examination and morphometric analysis of membranous airway dimensions. The relationships of smooth muscle shortening to PL and airway dimensions were analyzed using multiple linear regression. The results show that airway smooth muscle shortening was greater at lower PL and in airways with larger internal perimeter and a greater number of folds per internal perimeter and that it was less in airways with greater inner wall area. We conclude that the magnitude and variability of airway smooth muscle shortening and airway narrowing in response to maximal constricting stimuli are influenced by mechanical factors related to airway wall geometry.

Airway Resistance↗
PubMed1995

CT of the chest: minimal tube current required for good image quality with the least radiation dose.

OBJECTIVE: We wanted to determine minimal tube current (mAs) required for consistently good image quality on conventional 10-mm collimation chest CT and effect of tube current reduction on detection of mediastinal and lung abnormalities. Tube current reduction is desirable to reduce patient radiation dose. SUBJECTS AND METHODS: Prospectively, 30 consecutive patients (mean weight, 68 kg; range, 34-93 kg) older than 45 undergoing conventional chest CT with standard technique (120 kVp, 400 mAs) had four additional sections imaged at reduced tube current (200, 140, 80, 20 mAs) at two levels (tracheal carina and left atrium). CT scans were evaluated in random order by two independent observers who were blinded to technical factors used. Subjective image quality was graded on a five-point scale from non-diagnostic to excellent. Visualization of mediastinal adenopathy (n = 18), pleural plaques (n = 17), effusions (n = 28), lung parenchymal nodules (n = 37), and emphysema (n = 15) were assessed. The 400 mAs scan was considered the reference standard. RESULTS: When compared with the reference technique (400 mAs), the first and second (200 mAs and 140 mAs) reduction levels showed no significant difference (p > .05) in subjective image quality. A significant difference (p < .001) was seen at the third and fourth (80 mAs and 20 mAs) reduction levels. However, no significant difference (p > .05) was seen in detection of mediastinal or lung parenchymal abnormalities with different tube currents. CONCLUSION: A twofold reduction in tube current (400-140 mAs) and resultant radiation dose did not cause a significant change in subjective image quality or in detection of mediastinal or lung abnormalities with conventional chest CT. One hundred forty milliampere-seconds is the minimal tube current required to provide good image quality in patients of average weight.

Aged↗
PubMed1992

Spectrum of tuberculosis in patients with HIV infection in British Columbia: report of 40 cases.

OBJECTIVE: To review the clinical features, treatment and outcome of all known cases of tuberculosis in patients with human immunodeficiency virus (HIV) infection in British Columbia between 1984 and 1990. DESIGN: Retrospective case review. SETTING: Provincial tuberculosis registry and university-affiliated HIV clinic. PATIENTS: All people with HIV infection in whom active tuberculosis was diagnosed during the study period. RESULTS: All 40 patients identified were men; their mean age was 38 years. Of the subjects 30 (75%) were homosexual, 6 (15%) were homosexual and used intravenous drugs, 2 (5%) just used intravenous drugs, and 1 (2%) had had heterosexual contact with prostitutes; for the remaining subject the risk factor for HIV infection was not established. In all cases cultures of specimens from 15 body sources yielded Mycobacterium tuberculosis. Thirty-five of the patients had acquired immunodeficiency syndrome (AIDS), and five had HIV infection uncomplicated except for tuberculosis. In 28 (70%) of the cases no AIDS-defining disease had previously been diagnosed, and in 23 (58%) extrapulmonary tuberculosis represented the AIDS-defining disease. Symptoms at presentation included weight loss (in 80% of the cases), fever (in 75%), cough (in 70%) and night sweats (in 55%). The mean CD4 lymphocyte count was 0.2 x 10(9)/L (in 15 cases). Tuberculin skin test results were positive in 8 of 16 cases. The most striking radiologic finding was intrathoracic adenopathy. All except one of the 36 patients who received appropriate treatment responded favourably at first. Adverse reactions necessitating changes in treatment occurred in 12 (33%) of the cases. Relapse occurred after completion of therapy in two cases (one at 3 weeks and the other at 9 months after treatment was stopped). Tuberculosis was the cause of death in five cases. CONCLUSIONS: Tuberculosis in people with HIV infection commonly presents as extrapulmonary disease and precedes or coincides with other AIDS-defining opportunistic infections. In most cases tuberculosis is the AIDS-defining disease. Even though radiologic findings are often unusual physicians should suspect tuberculosis. A careful examination for evidence of disease at multiple sites should be done. The duration and choice of therapy must be adequate to avoid relapse.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Detection of dysplasia and carcinoma in situ by ratio fluorometry.

Fluorescence bronchoscopy was performed in 82 volunteers recruited from occupational groups at risk of exposure to asbestos and/or diesel fumes to determine whether differences in tissue autofluorescence between normal and malignant bronchial tissues can be used to improve the sensitivity of standard fiberoptic bronchoscopy in detecting dysplasic and carcinoma in situ (CIS). This study consisted of 25 nonsmokers, 40 exsmokers, and 17 current smokers with mean ages of 52, 55, and 49 yr, respectively. Tissue autofluorescence was induced by a blue light from an He-Cd laser coupled to the illumination channel of the bronchoscope and analyzed by a ratiofluorometer. One or more sites of moderate or severe dysplasia were found in 12% of the exsmokers and current smokers but in none of the nonsmoker volunteers. CIS was found in two of the exsmokers. The sensitivity of fluorescence bronchoscopy (86%) was found to be 50% better than that of conventional white-light bronchoscopy (52%) in detecting dysplasia and CIS. Pre- and post-bronchoscopy sputum cytology failed to detect these precancerous lesions. Our results suggest that fluorescence bronchoscopy may be an important new method that can improve the ability to detect and localize precancerous and/or CIS lesions.

Asbestos↗
PubMed1991

DNA adducts in bronchial biopsies.

To investigate the feasibility of measuring DNA-carcinogen adducts in the lungs of non-surgical patients, endobronchial biopsies were obtained from 78 patients undergoing routine diagnostic bronchoscopy. Lung cancer was present in 37 (47%) of the patients. DNA was isolated from the tissues and analyzed by HPLC- or nuclease-PI-enriched 32P-postlabelling, using procedures selective for aromatic adducts. Chromatograms from all 28 current smokers showed a distinctive diagonal adduct zone which was present in only 24 of 40 ex-smokers and 4 of 10 lifetime non-smokers. Adduct levels and chromatographic patterns were similar in bronchial tissue from different lobes of the lung, in bronchial and alveolar tissue, and in tumor and non-tumor bronchial tissue taken from the same subject. Bronchial DNA adduct levels were strongly associated with cigarette smoking status and dropped rapidly after smoking ceased. Higher levels of DNA adducts seen in the lung-cancer patients were mainly due to cigarette smoking. Frequent alcohol intake was the only dietary factor associated with higher levels of bronchial DNA adducts. We conclude that the level of bronchial DNA adducts is strongly associated with cigarette-smoking history and with alcohol intake, but is not associated with lung cancer independently from its relation to smoking. The results indicate the feasibility of using 32P-postlabelling to detect and quantitate genetic damage in bronchial biopsy specimens.

Aged↗
PubMed1991

Lung function and chest radiograph abnormalities among construction insulators.

We carried out a prevalence survey of pulmonary health parameters among current and retired construction insulators (50 years old and older) from all areas of British Columbia, Canada. The study population included 59 active workers (81 percent participation in this group) and 29 workers who were retired or inactive due to illness (69% participation). Radiograph results were compared to those from actively working bus mechanics from the same age group, and retired grain and civic workers, who were all tested in the same manner. Chest radiographs were read independently by two readers and were graded according to the ILO classification system. Pleural abnormalities alone were found in 34% (20) of active workers (5% in comparison group) and 45% (13) of non-active workers (14% in comparison group). Rates for parenchymal abnormalities for these same groups (ILO grade 1/0 or higher) were 17% (5%) and 20% (5%), respectively. Airflow obstruction was present in 35% (31) of the insulators and was associated with age and the presence of diffuse pleural thickening, and 5 or more years of employment in pulp mills. Restrictive lung function was present in 22% (19) of the insulator population and was associated with age and radiographic evidence of parenchymal fibrosis. The results indicate that construction insulators, a group at high risk for asbestos-related lung disease, also have a high prevalence of airflow obstruction. This was associated not only with smoking, but also with diffuse pleural thickening and a history of pulp-mill employment, suggesting that airflow obstruction in this population is also partly work related.

Aged↗
PubMed1991

Solitary pulmonary nodule: high-resolution CT and radiologic-pathologic correlation.

Edge and internal characteristics of pulmonary nodules evaluated with high-resolution computed tomography (HRCT) were correlated with the pathologic specimens in 93 patients. Speculation correlated pathologically with irregular fibrosis, localized lymphatic spread of tumor, or an infiltrative tumor growth pattern and was observed in six of 11 benign nodules (55%) and 74 of 85 malignant nodules (87%). Pleural tags were observed in three benign nodules (27%) and 49 malignant lesions (58%); pathologically, these represented fibrotic bands usually associated with juxta-cicatricial pleural retraction. Bubblelike areas of low attenuation within the nodule were observed in 21 malignant lesions (25%) and only one benign nodule (9%). They were observed most commonly in bronchioloalveolar carcinomas (seven of 14) and were due either to patent small bronchi or small, cystic spaces within neoplastic glands. Malignant nodules as a group were larger than benign lesions (P = .02) and more commonly demonstrated a spiculated contour (P less than .05), lobulation (P less than .001), and inhomogeneous attenuation (P less than .05).

Adult↗
PubMed1990

Emphysema in silicosis. A comparison of smokers with nonsmokers using pulmonary function testing and computed tomography.

The presence of emphysema in silicosis is believed to be secondary to the development of progressive massive fibrosis (PMF). However, it is difficult to separate out other causative factors, particularly cigarette smoking. In order to attempt to distinguish these factors, we examined 30 patients with silicosis by means of pulmonary function testing and computed tomography (CT) scans of the chest. Eighteen of these patients were either exsmokers or current smokers, and 12 of them were nonsmokers. The CT scans were read independently by two observers on two separate occasions. Silicosis was graded on a 5-point scale from 0 to 4; emphysema was graded as a percentage of lung involved. Percent emphysema was associated with level of pulmonary function (FEV1, FVC, and DLCO) independent of its association with either cigarette smoking or silicosis grade (p less than 0.01). Silicosis grade was associated with DLCO (p less than 0.05) independent of its association with either cigarette smoking or percent emphysema, but was not associated with level of FEV1 or FVC. In the group without PMF (silicosis Grade 0, 1, or 2), smokers had worse emphysema than nonsmokers (p less than 0.01); there was no such difference among the patients with PMF (silicosis Grade 3 or 4). Only one of the nonsmoking subjects with silicosis but without PMF had any emphysema detected on CT. Our data suggest that silicosis, in the absence of PMF, does not cause significant emphysema, and that it is primarily the degree of emphysema rather than the degree of silicosis that determines the level of pulmonary function.

Adult↗
PubMed1990

Methacholine responsiveness among working populations. Relationship to smoking and airway caliber.

It has been suggested that the development of bronchial hyperresponsiveness (BHR) in some smokers may be an intermediate event in the progression to chronic obstructive pulmonary disease in this group. If this is true, prevalence data on BHR in a general population should show an independent association between BHR and smoking status. To test this, we analyzed BHR to inhaled methacholine in 654 white men without known asthma, in relation to smoking, skin-test reactivity, type of work (office versus industrial), and indicators of baseline airway caliber (FEV1 % predicted and FEV1/FVC). BHR was measured in the traditional way (PC20) and as the slope of FEV1 versus the methacholine concentration (linear scale). A PC20 of less than 16 mg/ml was considered "responsive" for analyses of this outcome. We found that although a positive skin test, smoking, and being an industrial worker all appeared to be significant predictors of increased BHR (p less than 0.05), once FEV1 (% predicted) and FEV1/FVC% were taken into account, none of these variables alone remained significantly associated with BHR. The strongest predictors of BHR were prechallenge FEV1 and FEV1/FVC (both p less than 0.01). The combination of smoking, atopy, and work groups, which identified a small subgroup of atopic smokers who were office workers, also remained significantly associated with increased BHR. We also used a regression model that allowed for comparison of predictors for BHR between the most responsive subset of the population (n = 84) and the remainder of the study population.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Peak expiratory flow rate in an elderly population.

A population survey was conducted in 1982-1983 among 3,812 persons aged 65 years and older residing in East Boston, Massachusetts, a geographically defined urban community. Three measurements of peak expiratory flow rate were obtained by using calibrated mini-Wright meters. Peak expiratory flow rate was strongly related to age, sex, smoking, and years smoked. After adjustment for these factors, low peak expiratory flow rate was associated with chronic respiratory symptoms (cough, wheeze, shortness of breath, exertional dyspnea, orthopnea, and paroxysmal nocturnal dyspnea; p less than 0.0001) and with certain cardiovascular variables (history of stroke, p = 0.0014; angina, p = 0.05; and high pulse rate, p = 0.004). No significant associations were found with history of myocardial infarction or systolic and diastolic blood pressures. Peak expiratory flow rate was positively related to education (p less than 0.0001) and income (p less than 0.0001). Peak expiratory flow rate also was strongly related (p less than 0.0001) to measures of functional ability and physical activity, self-assessment of health, and simple measures of cognitive function. The correlations of peak expiratory flow rate with pulmonary symptoms and other indices of chronic disease raise the possibility that peak expiratory flow rate will predict mortality in an elderly population.

Age Factors↗
PubMed1989

Limitations of computed tomography in the assessment of emphysema.

Thirty-eight patients undergoing lobectomy or pneumonectomy for carcinoma had preoperative computed tomography (CT) of the chest. Twenty-seven had both 1.5 mm and 10 mm collimation scans, and eleven had 10 mm collimation images only. These images were analyzed for the extent and severity of emphysema, and the analysis compared to the pathologic findings in the corresponding transverse slice of lung. The latter was graded by a modification of a panel of standards and by a grid system numerically expressing extent and severity. The grid system is theoretically superior to the panel of standards because it allows better quantitation of early emphysema and, contrary to the set of standards, is designed to analyze transverse CT images and corresponding pathologic slices. There was good correlation between the CT score and the pathologic score using the panel of standards (r = 0.81, p less than 0.001) but a lower correlation with the grid system (r = 0.70, p less than 0.001). The correlation improved slightly with 1.5 as compared to 10 mm collimation scans. Close comparison between the CT and grid scores showed that CT was sensitive in demonstrating early distal acinar and irregular emphysema. However, CT consistently underestimated the extent of centriacinar and panacinar emphysema because most lesions less than 0.5 cm in diameter were missed. We conclude that CT is insensitive in detecting the earliest lesions of emphysema.

Humans↗
PubMed1988

Peripheral leucocyte count and longitudinal decline in lung function.

A six year follow up study of 750 aluminium smelter workers was undertaken to evaluate the relationship between the leucocyte count at the start of the study and the rate of decline in lung function. An inverse relationship between the leucocyte count and the forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) was present cross sectionally irrespective of cigarette smoking habit. The initial leucocyte count was also significantly related to the mean annual decline in FEV1 in smokers (p = 0.04) but not in former smokers or those who had never smoked. These observations suggest that the leucocyte count is a factor influencing the annual decline in FEV1 in smokers.

Adult↗
PubMed1988

A longitudinal study of the occurrence of bronchial hyperresponsiveness in western red cedar workers.

Two hundred twenty-seven workers in a western red cedar sawmill underwent methacholine bronchoprovocation testing at least 2 times during 3 surveys over a 2-yr period. At the first survey, workers completed a respiratory and occupational questionnaire, performed spirometry, gave serum for measurement of plicatic acid-specific IgE antibodies by radioallergosorbent testing, and had skin prick tests to detect atopy. Bronchial hyperresponsiveness was present initially in 18% of the workers. Approximately 15% of those with initially no hyperresponsiveness developed hyperresponsiveness during the follow-up period; 15% of those with initial hyperresponsiveness also lost it during follow-up. Development of hyperresponsiveness tended to coincide with a decrease in level of pulmonary function, whereas loss of hyperresponsiveness was associated with improvement in pulmonary function. Workers with either persistent bronchial hyperresponsiveness or with varying responsiveness had a higher prevalence of plicatic acid IgE antibodies and lower levels of initial pulmonary function than did workers with persistent nonresponsiveness. Workers with persistent hyperresponsiveness had higher initial estimated total airborne dust exposure than did other workers. Age, duration of sawmill employment, atopy, race, and cigarette smoking did not influence the occurrence of hyperresponsiveness. Levels of plicatic-acid-specific IgE antibodies did not change substantially over the 2 yr. These results indicate that immunologic sensitivity to plicatic acid and change in airway caliber are associated with the occurrence of bronchial hyperresponsiveness in cedar workers.

Allergens↗
PubMed1988

Airway size and the rate of pulmonary function decline in grain handlers.

Tracheal diameter and chest dimensions were measured from postero-anterior chest radiographs in grain handlers to prospectively identify airway size and chest size-related predictors of the rate of pulmonary function decline. A total of 634 grain workers were studied at the initial survey, of whom 239 satisfied the following inclusion criteria: (1) had a satisfactory chest radiograph taken at the initial survey in 1975, (2) performed spirometry at the 1975, 1978, and 1981 surveys, and (3) had no change in smoking status from 1975 to 1981. Radiographic measurements consisted of height of the right lung, transverse diameter of the chest at the level of the right diaphragm and at a level two-thirds up the right lung, and tracheal diameter (Tr). Areas of both lungs were measured by planimetry. Tr was only weakly related to height (r = 0.24). Increasing age was strongly associated with faster rates of FEV1 decline. After adjusting for the effects of age and cigarette smoking, Tr was the only radiographic measurement associated with FEV1 decline. Workers with Tr of 16 mm or less lost an average of 0.2% of their FEV1 per year compared to 0.9% per year for those with larger tracheas. This association was not modified by dust exposure estimates based on measurements of total dust. However, the strength of the association did depend upon smoking status, being strongest in current cigarette smokers (Tr less than or equal to 16 mm lost 0.2% annually and Tr greater than or equal to 21 mm lost 1.4% annually).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Desquamative interstitial pneumonia. Computed tomographic findings before and after treatment with corticosteroids.

Noninvasive methods for diagnosis, assessing prognosis, and following response to treatment in idiopathic pulmonary fibrosis (IPF) have yet to prove their usefulness. We report a patient with desquamative interstitial pneumonia (DIP) in whom computed tomography (CT) suggested the diagnosis by the presence of patchy areas of haziness predominantly in a peripheral distribution. The chest x-ray and physical examinations, and the arterial blood gases showed normal findings after one month of treatment with corticosteroids, at which time the CT scan and lung volumes were still abnormal. At three months, lung volumes and the CT scan were normal. Hazy densities in a peripheral distribution on CT may indicate active IPF associated with a good prognosis.

Adult↗
PubMed1988

Hyperinflation in asthma and emphysema. Assessment by pulmonary function testing and computed tomography.

To assess the role of emphysema on the hyperinflation in chronic asthma, we studied 20 subjects with irreversible airflow limitation. Ten of the subjects had asthma and had never smoked; the other ten were cigarette smokers. Pulmonary function testing and chest computed tomography (CT) scans were performed on all subjects. Emphysema was graded using a score based on the percentage of lung involved on CT scan. There was good inter- and intra-observer agreement for the emphysema scores. The median emphysema score was 0 percent in the nonsmoking group and 10 percent in the smoking group. All smokers with a total lung capacity (TLC) of greater than 120 percent predicted had evidence of emphysema on the CT scan. None of the asthmatic subjects with a TLC greater than 120 percent predicted had emphysema identifiable on CT scan. We conclude that chronic asthma with severe hyperinflation does not result in emphysema.

Adult↗
PubMed1988

Fate of grainhandlers with bronchial hyperreactivity.

Bronchial reactivity to methacholine and to grain dust were determined in a group of grainhandlers whose spirometry was being studied prospectively. Six workers showed specific bronchial responses to grain dust (indicative of occupational asthma), 21 did not show reactivity to grain dust but had bronchial hyperreactivity to methacholine and 40 had neither. Those with hyperreactivity were older, had lower FEV1 at initial examination and were more likely to experience a significant decline in FEV1 over a single working shift. Over 6 years of follow-up, those with hyperreactivity were not more likely to leave work and although they showed a more rapid decline in lung function over the period, because of the small number of individuals studied the difference between those with and without bronchial hyperreactivity was not significant. Among those with hyperreactivity to methacholine, there was a significant positive association between change in FEV1 over a single workshift and change in FEV1 over six years of followup, not seen in those without hyperreactivity to methacholine. Moreover, reactivity to methacholine was a stable observation over 6 years in the majority of studied individuals. We conclude that in the presence of bronchial hyperreactivity to methacholine, change in FEV1 over a single workshift more precisely predicts the trend in FEV1 over time in grainhandlers.

Adult↗