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Biomedical subjects

O F Pedersen

Publications and source records attributed to O F Pedersen.

At least 19 recordsLinked to original sources
PubMed1992

Respiratory disorders and atopy in cotton, wool, and other textile mill workers in Denmark.

A cross-sectional study of respiratory disorders and atopy in Danish textile industry workers was conducted to survey respiratory symptoms throughout the textile industry, to estimate the association of these disorders with atopy, and to study dose-response relationships within the cotton industry. Workers at cotton mills, a wool mill, and a man-made fiber (MMF) mill were examined. Four hundred nine (90%) of the 445 workers participated in this survey, i.e., 253, 62, and 94 workers at the cotton mills, the wool mill, and the MMF mill, respectively. An interview designed to assess the prevalence of common respiratory and allergic symptoms was given to all workers willing to participate, and blood samples were drawn. Lung function measurements determined a baseline FEV1, FVC and the change in FEV1 and FVC during work hours on a Monday. The working environment was examined for dust, bacteria, endotoxins, and molds, and the exposure was estimated for each participant. The mean personal samples of airborne respirable dust and respirable endotoxin were highest in the cotton industry, i.e., 0.17-0.50 mg/m3 and 9.0-126 ng/m3 respectively, whereas mold spores were found in the highest concentrations in the wool mill: 280-791 colony-forming units (cfu)/m3. Only small concentrations of microorganisms were found in the MMF mill. The mean change in FEV1% and FVC% was greatest among atopic individuals in both cotton and wool industry and other textile industries although the differences were not significant. FEV1% and FVC% in the cotton workers were significantly associated with the cumulative exposure to respirable endotoxin. Byssinosis was diagnosed only in the cotton industry. We found a dose-response relationship between endotoxin exposure and byssinosis, and a significant association between A-1-A serum concentrations less than or equal to 35 mumol/liter and byssinosis, a finding we are further evaluating in subsequent studies.

Animals↗
PubMed1992

Inhalation of diethylamine--acute nasal effects and subjective response.

Adult volunteers were exposed to 25 ppm (75 mg/m3) diethylamine in a climate chamber for 15 min in order to study the acute nasal reactions to an exposure equivalent to the present threshold limit value-short-term exposure limit. Changes in nasal volume and nasal resistance were measured by acoustic rhinometry and by rhinomanometry. Acute change in nasal volume, usually seen as acute nasal mucosa response to thermal stimuli, was not observed, nor was an acute change in nasal airway resistance. In a subsequent experiment, the aim was to measure acute sensory effects. Exposure to a concentration increasing from 0 to 12 ppm took place for 60 min, equal to an average concentration of 10 ppm (30 mg/m3). A moderate to strong olfactory response and distinct nasal and eye irritation were observed. In spite of considerable individual variation, the results were in agreement with sensory effect estimates obtained from animal studies.

Acoustics↗
PubMed1992

Delayed effects of NO2 exposure on alveolar permeability and glutathione peroxidase in healthy humans.

Potential toxic effects of prolonged NO2 exposure below the current threshold limit value (TLV) were examined in 14 healthy, nonsmoking adults. The subjects were exposed to 2.3 ppm NO2 and to clean air for 5 h with a 1-wk interval between exposures. Physiologic and biochemical measurements were obtained during the exposures and until 24 h after. A 14% decrease in serum glutathione peroxidase activity (GSH-Px) was observed 24 h after the start of the NO2 exposure, while indications of a 22% decrease in alveolar permeability were found 11 h after the start. There were no indications of mucous membrane irritation or of decreased lung function during or after NO2 exposures. The results support the assumption that a delayed response is a feature of the human reaction to NO2 even below the current TLV of 3 ppm, and they stress the importance of an extended period of observation in future NO2 exposure studies.

Adult↗
PubMed1991

Acoustic rhinometry: values from adults with subjective normal nasal patency.

The nose with normal feeling of nasal patency, and no gross structural changes has been described in 82 individuals by acoustic rhinometry. Curves for one and both sides of the nasal cavity and before and after decongestion have been recorded. We have found that the minimal cross-sectional area (MCA) is located anteriorly in the nasal cavity; in some subjects it is localized at the head of the inferior turbinate and in other subjects more anteriorly at the nasal valve. After decongestion MCA moves even more anteriorly. Beyond the MCA the dimension of the nasal cavity increases, with maximal effect of decongestion at 4 cm from nostrils. Decongestion increases the total volume of the nasal cavity by 35%.

Acoustics↗
PubMed1990

Turbinate hypertrophy. Evaluation of the nasal cavity by acoustic rhinometry.

We used acoustic rhinometry to assess the geometry of the nasal cavity. The cross-sectional area of the nasal cavity as a function of distance from the nostrils was obtained. Seventeen patients with hypertrophy of the inferior turbinate and septal deviations were examined preoperatively and postoperatively; 34 normal subjects served as controls. The cross-sectional area at the anterior part of the nose suggested that skeletal hypertrophy of the inferior turbinate might be expected in the side opposite the main septal deviation. Unilateral inferior turbinoplasty seems advisable.

Acoustic Impedance Tests↗
PubMed1990

Assessment of changes in eye redness by a photographic method and the relation to sensory eye irritation.

The purpose of the present study was to evaluate the relation between photographically assessed changes in eye redness and sensory eye irritation in 17 patients suffering from hayfever, provoked by increasing doses of birch pollen in the eye. Pre- and post-exposure diapositives were compared in a randomized and double blind design by a panel of five members. By evaluating the photographs we found a high reproducibility between panel members and for repeated evaluation by the individual panel member. Furthermore, we found that the photographic method was more sensitive for measurements of changes in eye redness than the observations normally performed during such conjunctival provocation tests. The correlations of the objective findings with the symptoms reported were good at high pollen doses, but at lower doses of birch pollen (about half the effective dose) a decreased eye redness was observed. We found that sensory irritation (often expressed as dryness) measured simultaneously by questionnaires, in general occurred before any increased eye redness. The study indicates that photographic measurement of eye redness is reproducible, sensitive, unbiased and therefore a useful tool in environmental studies. Furthermore we demonstrated that the relation between eye redness and eye irritation is interestingly biphasic and may need further clarification.

Conjunctivitis, Allergic↗
PubMed1990

Pulmonary function and bronchial reactivity in asthmatics during low-level formaldehyde exposure.

This study evaluated whether formaldehyde, at concentrations similar to those found in the indoor environment, could produce adverse effects on the lower airway of 15 asthmatic persons with documented bronchial hyperresponsiveness who were exposed for 90 min in a climate chamber to clean air containing formaldehyde vapor at levels of 0.85 mg/m3, 0.12 mg/m3, and 0.008 mg/m3. No significant changes in forced expiratory volume in 1 sec (FEV1), airway resistance (Raw), specific airway resistance (SRaw), and flow-volume curves could be detected during formaldehyde exposure. Furthermore, histamine challenge tests performed immediately after formaldehyde exposure showed no evidence of changes in bronchial reactivity. No late reactions were registered during the first 14-16 hr after exposure. The results suggest that residential levels of formaldehyde are of minor importance in the emergence of pulmonary symptoms. Discrepancies between the present study and previous data may be due to differences in environmental conditions.

Adolescent↗
PubMed1990

Evaluation of the effect of localized skin cooling on nasal airway volume by acoustic rhinometry.

Ten healthy subjects (four men and six women) were subjected to localized skin cooling by submersion for 5 min of both feet and, in another experiment, one hand and forearm into ice-cold water. Repeated measurements of nasal cavity volumes by a new method, acoustic rhinometry, showed characteristic patterns ranging from marked increases in volumes lasting the entire exposure period to transient monophasic or biphasic responses to no change at all. The pattern in individual subjects was reproducible with the two methods of cooling, and it could be characterized by five types when related to baseline measurements during the preexposure period. Because of large minute-to-minute variations, probably determined by local differences and fluctuations in blood flow in tissues through the nose, evaluation of induced changes in the nasal cavity volume cannot be based on single measurements as has frequently been done in the past by using rhinomanometry as the experimental method. The mechanisms behind the characteristic patterns in immediate human nasal response to local skin cooling challenge remains to be explored.

Adult↗
PubMed1989

Dust exposure, eye redness, eye cytology and mucous membrane irritation in a tobacco industry.

In a study of 75 workers employed in a tobacco factory producing cheroots we measured cellular contents of tear fluid, redness of eyes, discomfort, total (0-5.7 mg/m3) and respirable dust in the breathing zone and total ambient dust by stationary sampling (0.08-1.0 mg/m3). A matched group of 50 office workers in a telephone company (total ambient dust concentration between 0.08-0.13 mg/m3) was similarly examined as referents. We found a difference between the two companies with regard to cell counts, with tobacco workers having the largest numbers except for lymphocytes. Among tobacco workers we furthermore found that the number of cuboidal and columnar epithelial cells increased during the day. The increase of cuboidal cells, however, occurred mainly in a small group of tobacco workers exposed to the highest concentrations of tobacco dust (mean = 1.26 mg/m3). No difference in the sensation of eye irritation was found between companies, but increased irritation in the morning was associated with increased exposure to total dust during the workshift among tobacco workers. A dose-dependent difference in photographically measured eye redness was found among the tobacco workers. It could not be explained by differences in tobacco smoking, sex, age, sleeping habits or use of glasses. Irritation of lips and upper airways as reported by questionnaire were more common in tobacco workers than in referents. In conclusion the tobacco workers, more often than the referents, had complaints and objective changes in the mucous membranes of the eyes. These may be related to tobacco dust exposure.

Adult↗
PubMed1989

Acoustic rhinometry: evaluation of nasal cavity geometry by acoustic reflection.

To study the geometry of the nasal cavity we applied an acoustic method (J. Appl. Physiol. 43: 523-536, 1977) providing an estimate of cross-sectional area as a function of distance. Acoustic areas in a model constructed from a human nasal cast, in the nasal cavity of a cadaver and in 10 normal subjects and two patients with well-defined afflictions of the nasal cavity, were compared with similar areas obtained by computerized tomography (CT) scans, a specially developed water displacement method, and anterior rhinomanometry. We found a coefficient of variation of the areas of less than 2% by the acoustic method compared with 15% for the rhinomanometric measurements. Acoustic areas correlated highly to similar areas obtained by CT scanning (r = 0.94) and by water displacement (r = 0.96). In two patients the acoustic method accurately outlined, respectively, a tumor in the nose and a septum deviation. It is concluded that this method provides an accurate method for measuring the geometry of the nasal cavity. It is easy to perform and is potentially useful for investigation of physiological and pathological changes in the nose.

Acoustics↗
PubMed1989

Acoustic rhinometry: evaluation of the nasal cavity with septal deviations, before and after septoplasty.

We introduce acoustic rhinometry as a new, objective method to assess the geometry of the nasal cavity. The cross-sectional area of the nasal cavity as a function of distance from the nostrils was obtained. A group of 21 patients with septal deformities was examined with acoustic rhinometry preoperatively and postoperatively. These values were compared with those of 21 normal control subjects. The minimal cross-sectional area (MCA) is located in the anterior part of the nose, and it shifts anteriorly under the effect of decongestion. The preoperative value of MCA is related to the location and severity of the anterior septal deformity. Postoperative smaller MCA found in the opposite side of that narrowed by a severe anterior septal deformity may be explained by the impact of septoplasty without reduction of a hypertrophic turbinate. A highly significant relation between MCA and the subjective feeling of nasal patency, before and after surgery, suggests that MCA is a valuable parameter to express nasal patency. Correction of posterior septal deformities is found to increase significantly the cross-sectional area posteriorly. The effect of decongestion in the postoperative values, however, suggests that the mucosa contributes even more to the cross-sectional area of the posterior part of the nose. Acoustic rhinometry seems very suitable for evaluation of the nasal cavity in cases where septoplasty and turbinoplasty is considered, as well as for the postoperative evaluation.

Adolescent↗
PubMed1987

Tear fluid electrolytes and albumin in persons under environmental stress.

Sixty-two subjects selected among 287 persons with indoor air complaints were exposed to a standard mixture of 22 different organic gases and vapors normally found in Danish houses. Persons were randomly assigned to one of four exposure groups, and each subject stayed during the test day from 10:00 AM to 4:00 PM under standardized conditions in a climate chamber. During exposure the blink frequency was recorded, and after exposure the tear fluid contents of serum albumin, potassium, and sodium were measured. It was found that the persons had an increased concentration of serum albumin in the tear fluid, and that exposure to high concentrations of organic gases and vapors induced a tear reflex-mediated dilution of the tears.

Adult↗
PubMed1987

Interdependent regional lung emptying during forced expiration: a transistor model.

We recognized similarities between isovolume pressure-flow curves of the lung and emitter-collector voltage-current characteristics of bipolar transistors, and used this analogy to model expiratory flow limitation in a two-generation branching network with parallel nonhomogeneity. In this model, each of two bronchi empty parenchymal compliances through a common trachea, and each branch includes resistances upstream and downstream of a flow-limiting site. Properties of each airway are specified independently, allowing simulation of differences between the tracheal and bronchial generations and between the parallel bronchial paths. Simulations of four types of parallel asymmetry were performed: unilateral peripheral bronchoconstriction; unilateral central bronchoconstriction; asymmetric redistribution of parenchymal compliance; and unilateral alteration of the bronchial area-transmural pressure characteristic. Our results indicate that multiple axial choke points can exist simultaneously in a symmetric lung when large airway opening-pleural pressure gradients exist; despite severe nonhomogeneity of regional lung emptying, flow interdependence among parallel branches tends to maintain a near normal configuration of the overall maximal expiratory flow-volume (MEFV) curve throughout a large fraction of the vital capacity; and sudden changes of slope of the MEFV curve ("knees" or "bumps") may reflect choking in one branch in a nonuniform lung, but need not be obvious even when severe heterogeneity of lung emptying exists.

Airway Resistance↗
PubMed1986

Density dependence of maximal expiratory flow before and during tracheal constriction in dogs.

The effect of carbachol-induced central bronchoconstriction on density dependence of maximal expiratory flow (MEF) was assessed in five dogs. MEFs were measured on air and an 80% He-20% O2 mixture before and after local application of carbachol to the trachea. Airway pressures were measured using a pitot-static probe, from which central airway areas were estimated. At lower concentrations of carbachol the flow-limiting site remained in the trachea over most of the vital capacity (VC), and tracheal area and compliance decreased in all five dogs. In four dogs, decreases in choke point area predominated and produced decreases in flows. In one dog the increase in airway "stiffness" apparently offset the fall in area to account for an increase in MEF. Density dependence measured as the ratio of MEF on HeO2 to MEF on air at 50% of VC increased in all five dogs. Increases in density dependence appeared to be related to increases in airway stiffness at the choke point rather than decreases in gas-related airway pressure differences. Lower concentrations produced a localized decrease in tracheal area and extended the plateau of the flow-volume curve to lower lung volumes. Higher concentrations caused further reductions in tracheal area and greater longitudinal extension of bronchoconstriction, resulting in upstream movement of the site of flow limitation at higher lung volumes. Density dependence increased if the flow-limiting sites remained in the trachea at mid-VC but fell if the flow-limiting site had moved upstream by that volume.

Air↗
PubMed1985

Configuration of maximum expiratory flow-volume curve: model experiments with physiological implications.

A two-compartment mechanical model of the lungs was constructed with two parallel peripheral and collapsible bronchi in series with one central and collapsible trachea. Maximal expiratory flow-volume (MEFV) curves similar to those obtained in most dogs and in some humans could be produced: a peak followed by a gently sloping plateau ending in a knee, where flow suddenly fell to a much smaller value approaching zero rather slowly over the last 25 to 50% of the expired vital capacity. It was shown that flow before the knee was limited in the trachea, and after the knee it was limited in the bronchi. Two patterns of changes in the configuration of the MEFV curve could be observed. Pattern of changes affecting the central airway, at a given volume, maximal flow during the first part of the expiration (i.e., before the knee) is decreased; the knee occurs at a lower lung volume; the flow at the beginning of the knee is decreased. This pattern was observed with the following interventions: decreased cross-sectional area of the trachea (partial obstruction); decreased axial tension of the trachea; and, increased frictional loss between the trachea and the bronchi. Pattern of changes affecting the airways in the periphery: the knee occurs at a higher lung volume; at a given volume, flow after the knee becomes smaller; the absolute flow at the start of the knee is almost unchanged. This pattern was observed with the following interventions: decreased cross-sectional area of the peripheral airways (partial obstruction); increased frictional loss upstream to the peripheral airways; and, decreased elastic recoil pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Airway dynamics in transition between peak and maximal expiratory flow.

Expiratory flow-volume curves with periodic interruption of flow showed flow transients exceeding maximal flow (Vmax) measured on the maximum expiratory flow-volume (MEFV) curve in a mechanical lung model and in five tracheotomized, vagotomized, open-chest, anesthetized dogs. Direct measurement of flow from the collapsing model airway showed that the volume of the flow transients in excess of the MEFV envelope was greater than that from the collapsing airway. Determination of wave-speed flows from local airway transmural pressure-area curves (J. Appl. Physiol. 52: 357-369, 1982) and photography of the airway led to the following conclusions. Flow transients exceeding Vmax are wave-speed flows determined by an initial and unstable configuration of the flow-limiting segment (FLS) with maximum compression in the midportion. The drop in flow from the peak to the following plateau is due to development of a more stable airway configuration with maximum compression at the mouthward end with a smaller area and a smaller maximal flow. When FLS jumps to a more peripheral position, the more distal airways may pass through similar configurational changes that are responsible for the sudden decrease of flow (the "knee") seen on most MEFV curves from dogs.

Animals↗
PubMed1985

Response of solvent-exposed printers and unexposed controls to six-hour toluene exposure.

The acute effects of toluene were studied in 43 male printers and 43 control subjects matched according to sex, age, educational level, and smoking habits. The mean age of the subjects was 36 (range 29-50) years. The printers had been exposed to solvents for 9 to 25 years during employment at flexo and rotogravure printing plants, while the controls had no history of solvent exposure. Each subject was exposed once in a climate chamber to either 100 ppm of toluene or clean air for 6.5 h preceded by a 1-h acclimatization period. The effects of toluene were measured from subjective votes with linear analogue rating scales on 16 items, and on the performance of 10 different tests measuring psychomotor skills, perceptual skills, and vigilance. Exposure to 100 ppm of toluene compared with exposure to clean air caused discomfort with complaints of low air quality, strong odor, fatigue, sleepiness, a feeling of intoxication, and irritation of the eyes, nose and throat. Furthermore, the subjects exposed to toluene showed decreased manual dexterity, decreased color discrimination, and decreased accuracy in visual perception. There was no significant difference in the effects of toluene on printers compared to those of toluene on controls, but tendencies toward a greater sensitivity were seen for the printers in two tests.

Adult↗