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Biomedical subjects

F Silverman

Publications and source records attributed to F Silverman.

18 recordsLinked to original sources
PubMed1991

Effect of low concentrations of ozone on inhaled allergen responses in asthmatic subjects.

The relation between inhalation of ambient concentrations of ozone and airway reactivity to inhaled allergens may be important in asthma, since both agents can produce inflammatory changes in the airways. Seven asthmatic patients (mean age 40 [SD 13] years), with seasonal symptoms of asthma and positive skin tests for ragweed or grass, took part in a study to investigate whether exposure to low concentrations of ozone potentiates the airway allergic response. The patients were studied during 4 separate weeks in the winter. In each week there were 3 study days: on days 1 and 3 methacholine challenges were carried out; and on day 2 the subject received one of four combined challenges in a single-blind design--air breathing followed by inhalation of allergen diluent (placebo); ozone followed by inhalation of allergen diluent; air followed by allergen; or ozone followed by allergen. The ozone concentration was 0.12 ppm during 1 h of tidal breathing at rest, and allergens were inhaled until the forced expiratory volume in 1 s (FEV1) had fallen by 15% (PC15). There were no significant differences in baseline FEV1 after exposure to ozone but PC15 was significantly reduced when allergen was preceded by ozone inhalation: the mean PC15 after air was 0.013 (SD 0.017) mg/ml compared with 0.0056 (0.0062) mg/ml after ozone (p = 0.042). Thus, low ozone concentrations, similar to those commonly occurring in urban areas, can increase the bronchial responsiveness to allergen in atopic asthmatic subjects. This effect does not seem to be the result of changes in baseline airway function.

Adult↗
PubMed1979

Fetal blood and tissue pH with moderate bradycardia.

Eleven patients with moderate fetal bradycardia in labor were studied by fetal scalp blood pH, continuous tissue pH, and umbilical arterty pH at delivery. The neonatal outcomes and biochemical data demonstrated that moderate fetal brdycardia does not indicate fetal distress.

Female↗
PubMed1979

Comparison of respiratory variables in grain elevator workers and civic outside workers of Thunder Bay, Canada.

We compared respiratory variables in 441 grain elevator workers with 180 civic outside laborers in Thunder Bay. The grain handlers had a lower frequency of both positive skin reactions to pollens and molds and a family history of asthma, which suggests that they may have been self-selected for a decreased tendency to develop allergic respiratory disease. There was a higher frequency of cough and rales and a small decrease in forced vital capacity and forced expiratory volume in one sec among the grain handlers, as compared to the civic workers matched for smoking. However, these differences between grain and nongrain workers were small in comparison to those between smokers and nonsmokers. There was no clear indication of a worsening of respiratory functions that could be attributed specifically to duration of employment as a grain elevator worker.

Adult↗
PubMed1979

Asthma and respiratory irritants (ozone).

Asthmatics appear to be more susceptible to the effects of air pollutants than nonasthmatics. The present studies were undertaken to examine the effects of exposing asthmatics to ozone concentrations that occur in the environment. Seventeen well-documented male and female asthmatics have been exposed for 2 hr in an environmental chamber to 0.25 ppm of ozone on one occasion (ozone) and to air on another occasion (air). Effects were assessed by measurements of pulmonary function obtained prior to (0 hr), every half-hour during and at the end of all exposures (2 hr). Paired t-test analysis of lung volumes, forced expiratory volume in 1 sec (FEV1.0), and maximum expiratory flow rates at 50% of vital capacity (V50%VC) showed no significant changes (p greater than 0.05) when the following comparisons were made: 0 hr air vs 0 hr ozone, 0 hr air vs. 2 hr air, 0 hr ozone vs. 2 hr ozone, 2 hr air vs. 2 hr ozone. There was variability in severity of asthma and pulmonary function status; most subjects were taking some form of medication at the time of study. Some asthmatics showed no change or improvement with both air and ozone and others developed greater reductions in pulmonary function with ozone than with air. Approximately one-third of the asthmatics demonstrated greater changes in V50%VC with exposure to 0.25 ppm of ozone relative to air exposure. These studies indicate that acute exposures to ozone at realistic concentrations in the environment can produce adverse responses in some asthmatics.

Adult↗
PubMed1979

Work of nasal breathing: measurement of each nostril independently using a split mask.

The work of nasal breathing was determined in human subjects as a measure of impedance to respiratory airflow. The nasal cavities were examined separately and simultaneously with a split mask; flow and pressure signals were fed to a microprocessor for on-line computation and printout of respired volumes and work of nasal breathing. An alternating resistive nasal cycle of 3--4 hours' duration was demonstrated in the majority of normal, resting subjects. Reciprocity of the resistive changes in each nasal cavity maintained a constant total nasal respiratory work load of about 0.2 Joules/litre. Moderate changes in breathing rate and tidal volume had little influence on work. Inspiratory work was 1.6 times that of expiration. Increases in resistance of the dependent nostril were seen when the lateral decubitus position was adopted. Increase in cephalic venous pressure and pathological nasal obstruction increased the work of nasal breathing.

Airway Obstruction↗
PubMed1979

Nasal aerodynamics.

The historical development of nasal aerodynamic measurement is discussed. Attention is drawn to the absence of a consensus on adequate rhinometric techniques and standards, which hampers the elevation of rhinometry to the universal clinical status of audiometric, impedance, or nystagmus measurement. A computer-aided technique is described which overcomes some problems of rhinometry, by measurement of the amount of energy the body devotes to moving respiratory air through each separate nasal cavity. Although the approach is different, our preliminary results confirm previous work and suggest that assessment of the work of breathing is a promising technique in the investigation of nasal respiratory airflow.

Airway Obstruction↗
PubMed1978

The effect of cigarette smoke on the human tear film.

We used a corneal microscope to measure the break up time of the tear film (BUT) in 14 young volunteers; four were men and all were non-smokers. Values under controlled conditions and after ten minutes of exposure to filtered air or to cigarette smoke in a room of 14.6 m3 were determined. Exposure to cigarette smoke was associated with a substantial (35--40%) and statistically significant (P less than 0.001) reduction of BUT. This may reflect an alteration in the relative proportions of the three constituents of the tear film. The chemical responsible, and the way in which it increases the flow of watery constituents and suppresses mucus and lipid secretion demand further research.

Adult↗
PubMed1977

Decrease of maximum work performance following ozone exposure.

A bicycle ergometer was used to measure maximum exercise oxygen consumption following 2 h of intermittent exercise in an environmental chamber ventilated with air (FA test) or filtered air plus 0.75 ppm ozone (PO test). Thirteen adult males performed both tests according to a random sequence. The maximum attained VO2 declined 10% (P less than 0.01), maximum attained work load was reduced by 10% (P less than 0.01), maximum ventilation decreased 16% (P less than 0.01), and maximum heart rate dropped 6% (P less than 0.05) in the PO test. At the highest common work load, heart rate and oxygen consumption were similar and ventilation was slightly higher (P less than 0.05); however, frequency of respiration increased 45% (P less than 0.01) and tidal voluem fell by 29% (P less than 0.01) following ozone exposure. During maximum exercise, the respiratory frequency was similar in both tests, but tidal volume was 21% lower (P less than 0.01) in PO experiments. Decreases in vital capacity and FEV1.0 as well as cough and chest discomfort were also noted following ozone exposure. We conclude that the reduction of maximum attained VO2 is a consequence of ventilatory limitation of maximum effort, probably related to respiratory discomfort.

Adult↗
PubMed1977

Steroid-dependent asthma treated with inhaled beclomethasone dipropionate. A long-term study.

The efficacy of inhaled beclomethasone dipropionate has been examined in 44 steroid-dependent asthmatics observed for 9 months to 2 years. A 3-month double-blind trial found that subjects treated with beclomethasone had a significant diminution in symptoms, were able to reduce their use of medication, and had improved maximum expiratory flow rates. Approximately one half were able to discontinue the use of oral prednisone within 9 months after starting beclomethasone, and a further one third reduced their dose by at least 50%. No characteristics could be defined to predict responsiveness to beclomethasone. The effectiveness of beclomethasone was sustained for as long as 2 years and was not associated with any abnormal urine, blood, or serum values or chest X-ray findings. Candidiasis of the palate appeared in approximately one third of the subjects and was usually transient. The chronic use of beclomethasone did not result in endocrine suppression.

Administration, Oral↗
PubMed1976

Permeability of dog lung endothelium to sodium, diols, amides, and water.

Bolus injection of T-1824-albumin, test indicator, and tritiated water into a jugular vein of the anesthetized dog and sequential sampling of blood from a carotid artery yielded multiple-indicator outflow patterns for the lung. Permeability-surface products of the test indicator for the lung endothelial barrier were obtained by comparison of test indicator with T-1824-albumin on the upslope of the test-indicator curve and correction for backdiffusion. The derived endothelial permeability coefficients, based on surface area/wet lung weight-500 cm2/g (mean +/- 2 SE, 10(-5) cm s(-1)), were: sodium ion, 2.9 +/- 0.8; ethylene glycol, 7.3 +/- 1.5; 1, 3-propranediol, 7.9 +/- 3.2; 1, 2-propanediol, 10 +/- 4; 1, 4-butanediol, 14 +/- 8; 1, 5-pentanediol, 21 +/- 6; 1, 6-hexanediol, 41 +/- 11; formamide, 16 +/- 9; acetamide, 13 +/- 4; propionamide, 31 +/- 12; butyramide, 42 +/- 24; valeramide, 79 +/- 12; tritiated water, 150 +/- 50. The backdiffusion correction varies from 8% for sodium to 75% for valeramide. A parallel-pathway model of blood-tissue passive exchange of small nonelectrolyte solutes is compatible with these results, with a lipid pathway through endothelial cells and an aqueous pathway possibly through interendothelial clefts.

Acetamides↗
PubMed1976

Pulmonary function changes in ozone-interaction of concentration and ventilation.

A total of 28 healthy young subjects have been exposed for 2 h to ozone (0.37-0.75 ppm) under conditions of either rest or intermittent light exercise (sufficient to increase the respiratory minute volume by a factor of 2.5). All pulmonary function tests (vital capacity, forced expiratory volume, maximum expiratory flow-volume curve, slope of phase III of alveolar nitrogen plateau) showed a significant deterioration relative to parallel control experiments. Responses were related to the dose of ozone as calculated from the product of concentration, exposure time, and respiratory minute volume during exposure, changes at 1 h averaging approximately one-half those seen at 2 h.

Adult↗
PubMed1975

Exercise responses following ozone exposure.

We have tested the response of 28 subjects to a three-stage ergometer test, with loads adjusted to 45, 60, and 75% of maximum aerobic power following ozone exposure. The subjects were exposed to one of 0.37, 0.50, or 0.75 ppm O3 for 2 h either at rest (R) or while exercising intermittently (IE) (15 min rest alternated with 15 min exercise at approximately 50 W. sufficient to increase VE by a factor of 2.5). Also, all subjects completed a mock exposure VE, respiratory frequency (fR), mixed expired PO2 and PCO2, and electrocardiogram were monitored continuously during the exercise test. Neither submaximal exercise oxygen consumption nor minute ventilation was significantly altered following any level of ozone exposure. The major response noted was an increase in respiratory frequency during exercise following ozone exposure. The increase in fR was closely correlated with the total dose of ozone (r = 0.98) and was accompanied by a decrease in tidal volume (r = 0.91) so that minute volume was unchanged. It is concluded that through its irritant properties, ozone modifies the normal ventilatory response to exercise, and that this effect is dose dependent.

Adult↗
PubMedDate not supplied

Effects of ozone exposure in Canadians and Southern Californians. Evidence for adaptation?

Comparison of published reports on physiological effects of exposure to ozone (O3) suggests that Canadians are more reactive than southern Californians. Responses of subjects and experimental methods were compared in a cooperative investigation of this apparent difference in reactivity. Four Canadians and four Californians were exposed to 0.37 ppm O3 in purified air at 21 degrees C and 50% relative humidity for 2 hours with intermittent light exercise. Exposures to purified air alone served as controls. Responses of subjects were similar to those observed previously: Canadians on the average showed greater clinical and physiological reactivity to exposure than did Californians, who were no more than minimally reactive. Canadians also showed larger increases in erythrocyte fragility following exposure. No methodological differences sufficient to explain different results of previous studies were found. Although other possible explanations have not been ruled out entirely, adaptation of southern Californians to chronic ambient O3 exposure is a rational hypothesis to explain these results.

Acetylcholinesterase↗
PubMedDate not supplied

Physiological effects of acute passive exposure to cigarette smoke.

Effects of passive inhalation of cigarette smoke at levels typically encountered in public buildings have been investigated. Twenty normal male and female nonsmokers (18 to 30 years) were each exposed for two hours on alternate days (in random order) to either room air or room air plus machine-produced cigarette smoke. Exposures were conducted in an unventilated chamber (14.6 m3). Subdivisions of lung volume, maximum expiratory flow-volume curves, single-breath nitrogen washout curves, blood carboxyhemoglobin levels, and heart rates were obtained before, during, and after exposure. A submaximal bicycle ergometer test and a symptom questionnaire were also administered after exposure. Statistical analysis revealed several significant differences between test and control days; the magnitude of the changes was small and of questionable biological significance, however, particularly when account was taken of the number of statistical comparisons made. Despite the relatively small physiological changes, subjective complaints were common-cough, and eye irritation, for example. It is concluded that in normal subjects the magnitude of physiological responses to acute exposures is minimal; thus arguments concerning effects rest on symptomatology and such other factors as the unknown risks of chronic exposure.

Adult↗
PubMedDate not supplied

Effects of particulate matter exposure and medication use on asthmatics.

The health risk associated with low-level air pollution exposure is still uncertain. The association between exposure and pulmonary function was assessed with personal sampling. Small, portable multipollutant samplers were used to assess personal exposure to particulate matter. Thirty-six asthmatic subjects participated in the study for up to 20 d in both summer (n = 10 d) and winter (n = 10 d); pulmonary function was assessed at the beginning and end of each sampling day, and medication use was recorded. A within-individual longitudinal analysis of the relationship between pulmonary function and particulate matter revealed an effect of season. In winter, pulmonary function increased as particulate exposure increased, which was explained by a confounding effect of medication use. Therefore, in addition to exposure, season of the year and medication use are factors that must be considered.

Air Pollutants↗