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Biomedical subjects

K R Anderson

Publications and source records attributed to K R Anderson.

At least 55 records · Page 3Linked to original sources
PubMed1994

Active and passive ozone samplers based on a reaction with a binary reagent.

Ozone is one of the most toxic common air pollutants (judging from short-term animal and human exposure studies at realistic concentrations) and one of the most difficult and expensive pollutants to control. Because of ozone's high chemical reactivity, its concentrations may vary greatly over short distances, and fixed-site air quality monitors may not accurately estimate exposures of human populations. Epidemiologic research on ozone's long-term health effects has been inconclusive, partly because of the lack of reliable personal exposure information. The objective of this project was to develop a practical personal ozone exposure monitoring technique, and to document its precision and accuracy in actual use by representatives of freely ranging, ozone-exposed populations. The project site, Los Angeles, is the nation's metropolitan area with the highest level of ozone pollution and, thus, probably the most important locale for personal exposure assessment. Our overall strategy was (1) to select the most promising laboratory technique for ozone detection from published literature and private communications; (2) to design and test personal monitors using this technique; and (3) when feasible, to evaluate concurrently alternative methodologies developed by others. As indicated below, parts 1 and 2 of our strategy yielded a limited success with respect to short-term active sampling, i.e., measuring personal ozone exposure levels during one to two hours with a monitor incorporating a battery-powered air pump of the type used in industrial hygiene investigations. The same approach was not successful in passive sampling, i.e., measuring exposure levels during multihour or multiday periods with a light-weight, diffusion-controlled "badge" sampler having no moving parts. Passive badge samplers could be calibrated reasonably well in laboratory exposures to ozone in otherwise pure air, but they greatly overestimated ozone levels in outdoor ambient air. Part 3 of our strategy yielded more promising information on an alternative passive badge design. After testing and rejecting two other possibilities, we chose a binary organic reagents, 3-methyl-2-benzothiazolinone acetone azine with 2-phenylphenol, as the most promising chemical detector of ozone. Filter papers impregnated with the binary reagent develop a characteristic intense pink color when exposed to ozone. The inventors, J.E. Lambert and associates of Kansas State University, had intended only to develop a rough qualitative ozone monitor (Lambert et al. 1989). However, our initial laboratory testing (in exposure chambers containing ozone in otherwise very clean air, away from humans), revealed fairly accurate quantitative response.(ABSTRACT TRUNCATED AT 400 WORDS)

Benzothiazoles↗
PubMed1993

Ureteroscopic cytologic diagnosis of upper tract lesions.

The definitive diagnosis of upper urinary tract lesions often relies on providing adequate tissue samples for cytopathologic review. Uretreopyeloscopy allows direct examination of these lesions and enables tissue sampling under visual control. A retrospective analysis of 11 patients with 13 abnormal upper tracts was performed, comparing sampling techniques performed under endoscopic vision (brush biopsy, fine-needle aspiration [FNA], and forceps biopsy) with standard retrograde catheter lavage. Forceps biopsy was the most accurate of the direct vision sampling methods (100%), although it provided adequate tissue only 56% of the time. Direct vision brush biopsy and FNA were better than forceps biopsy at providing adequate tissue but were less accurate, at 83% and 89%, respectively. Surprisingly, retrograde catheter lavage was superior to direct vision sampling methods. These results may be attributable to patient selection bias in that five of seven upper tracts found to have malignancy had multifocal disease. One patient developed a distal ureteral stricture from instrumentation that was managed successfully with an endoureterotomy.

Adult↗
PubMed1992

Controlled exposures of volunteers to respirable carbon and sulfuric acid aerosols.

Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently to the lower respiratory tract. To investigate this issue, we exposed 15 healthy and 15 asthmatic volunteers in a controlled-environment chamber (21 degrees C, 50 percent relative humidity) to four test atmospheres: (i) clean air; (ii) 0.5-microns H2SO4 aerosol at approximately 100 micrograms/m3, generated from water solution; (iii) 0.5-microns carbon aerosol at approximately 250 micrograms/m3, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (iv) carbon as in (iii) plus approximately 100 micrograms/m3 of ultrafine H2SO4 aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (iv) became attached to carbon particle surfaces, and that most particles remained in the sub-micron size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation approximately 50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at end-exposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H2SO4 or carbon, separate or interactive, on health measures. Group data showed no more than small equivocal effects of any exposure on any health measure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Exposures of older adults with chronic respiratory illness to nitrogen dioxide. A combined laboratory and field study.

We combined field and laboratory experimentation to evaluate the effects of nitrogen dioxide in a panel of Los Angeles area residents with chronic respiratory illness, 15 men and 11 women aged 47 to 69. All had heavy smoking history, chronic symptoms, and low FEV1; some also had low FVC. During the fall-winter high-NO2 season, they monitored themselves for 2-wk periods using spirometers in the home, passive NO2 sampling badges, and diaries to record time and activity patterns and clinical status. In the middle of each self-monitoring week they were exposed in a chamber, once to clean air and once to 0.3 ppm NO2. Chamber exposures were double blind, lasted 4 h, and included four 7-min exercise sessions with average ventilation rates near 25 L/min. Symptom reports and hourly forced expiratory function tests showed no statistically significant differences between clean air and NO2 chamber exposures, although peak flow showed a approximately 3% loss with NO2 relative to clean air during the first 2 h of exposure only (p = 0.056). No significant overall differences were found between field self-measurements and measurements of lung function in the chamber or between field measurements in clean air and NO2 exposure weeks. Field data showed that group average lung function and symptom levels were worse in the morning than later in the day (p < 0.005) but otherwise were stable over 2 wk. Even though most subjects smoked and stayed indoors 80 to 90% of the time, personal NO2 exposures correlated significantly with outdoor NO2 concentrations as reported by local monitoring stations.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Calcium channel blocking and positive inotropic activities of ethyl 5-cyano-1,4-dihydro-6-methyl-2-[(phenylsulfonyl)methyl]-4-aryl-3- pyridine-carboxylate and analogues. Synthesis and structure-activity relationships.

The synthesis and pharmacological evaluation of a series of 2-[(arylsulfonyl)methyl]-4-aryl-5-cyano-1,4-dihydropyridine-3-carboxylic acid esters and analogues are described. These compounds possess a unique profile namely, calcium channel blocking and positive inotropic activities in vitro. Compound 54 was selected as the best compound in the series and was studied in detail. The synthesis and biological profiles of enantiomers of 54 are also reported. The data indicate that although the calcium channel blocking property of 54 is stereospecific the positive inotropic activity is not. Examples of 3- and 6-cyano and other closely related 1,4-dihydropyridine derivatives are described and evaluated for comparison and were found to be devoid of dual activities mentioned above.

Animals↗
PubMed1990

Respiratory responses of young asthmatic volunteers in controlled exposures to sulfuric acid aerosol.

Thirty-two asthmatic volunteers 8 to 16 yr of age, recruited through local schools and private physicians, were exposed in a chamber to clean air (control condition) and to sulfuric acid aerosol at a "low" concentration (46 +/- 11 micrograms/m3; mean +/- SD) and at a "high" concentration (127 +/- 21 micrograms/m3). Acid aerosols had mass median aerodynamic diameters near 0.5 microns with geometric standard deviations near 1.9. Temperature was 21 degrees C, and relative humidity was near 50%. Subjects were exposed with unencumbered oronasal breathing for 30 min at rest plus 10 min at moderate exercise (ventilation rate approximately 20 L/min/m2 of body surface). A subgroup (21 subjects) were exposed similarly to clean air and to "high" acid (134 +/- 20 micrograms/m3) with 100% oral breathing. Increased symptoms and bronchoconstriction were found after exercise under all exposure conditions. For the group, symptom and lung function responses were not statistically different during control and during acid exposures with unencumbered breathing or with oral breathing. By contrast, other investigators have reported statistically significant lung function disturbances in groups of young asthmatics exposed similarly with oral breathing. A minority of our subjects showed possibly meaningful excess bronchoconstriction with "high" acid exposure relative to control with both routes of breathing. This could be the result of chance, or it could suggest the existence of an acid-sensitive subpopulation of young asthmatics.

Adolescent↗
PubMed1989

Effect of droplet size on respiratory responses to inhaled sulfuric acid in normal and asthmatic volunteers.

We exposed groups of healthy and asthmatic volunteers to sulfuric acid aerosols with volume median droplet diameters of approximately 20, 10, and 1 microns, at nominal concentrations of 2,000 micrograms/m3, and exposed them similarly to aerosols of purified water as a control. Exposures lasted 1 h each, and included three 10-min periods of exercise (ventilation rate typically 40 to 45 L/min). Exposures occurred in randomized order 7 days apart. Temperature was 10 degrees C, relative humidity was approximately 100% in 20- and 10-microns (fog) exposures, and approximately 75 to 80% in 1-micron aerosol exposures. Healthy subjects showed no statistically significant changes in lung function or in bronchial reactivity to methacholine attributable to acid exposures. They showed significant increases in lower and upper respiratory irritant symptoms when exposed to 20- or 10-microns acid fog, but not when exposed to 1-micron acid aerosol. Asthmatics showed significant excess decreases in forced expiratory performance, increases in airway resistance, and increases in irritant symptoms during acid exposures, relative to control conditions. Lung function changes in asthmatics tended to increase with time during exposure; they did not vary significantly with acid droplet size. Symptoms in asthmatics were slightly worse with 10- or 20-microns fog as compared with 1-micron aerosol. In a few instances, symptoms and lung function decrements necessitated stopping exercise or terminating the exposure early. Thus, asthma is a risk factor for unfavorable physiologic response to sulfuric acid at occupational exposure concentrations. Large droplet size (i.e., fog) tends to exacerbate short-term symptomatic response, but we have not been able to demonstrate a consistent effect of droplet size on physiologic response.

Adult↗
PubMed1988

Respiratory dose-response study of normal and asthmatic volunteers exposed to sulfuric acid aerosol in the sub-micrometer size range.

Twenty-one healthy and 21 asthmatic volunteers were exposed to respirable sulfuric acid aerosol (mass median particle diameter approximately 0.9 micron, geometric standard deviation 2.5) in a chamber at 21 degrees and 50% relative humidity. Measured sulfuric acid concentrations averaged 0, 380, 1060, and 1520 micrograms/m3 (in the occupational range, higher than concentrations observed in ambient air pollution). Exposures to different concentrations occurred in randomized order 1 week apart. They lasted 1 hr and included three 10-min periods of heavy exercise. Healthy volunteers showed no statistically significant changes in pulmonary function, airway reactivity to inhaled methacholine, or overall reporting of irritant symptoms which could be attributed to acid exposure. They did show a slight statistically significant (P less than .01) increase in cough with increasing acid concentration. At the two highest acid concentrations, asthmatics showed significant increases in irritant symptoms and decrements in pulmonary function, without significant changes in airway reactivity. Their function decrements appeared to increase with time during exposure. Previous studies in fog (10 degrees, median particle diameter approximately 10 micron) with similar concentrations of sulfuric acid showed more symptoms but less pulmonary function change, perhaps reflecting different sites of particle deposition in airways and/or different degrees of neutralization by airway ammonia. This and earlier evidence predicts little, if any, acute irritant response in short-term (1 hr or less) exposures to sulfuric acid at concentrations found in ambient air pollution.

Administration, Inhalation↗
PubMed1985

Effects of heat and humidity on the responses of exercising asthmatics to sulfur dioxide exposure.

Twenty-two asthmatic young adult volunteers, predetermined to be reactive to sulfur dioxide (SO2) with exercise at normal room temperature, were studied to document short-term effects of SO2 exposure under hot conditions, both humid and dry. For comparison, similar exposures were conducted at mild temperatures. All subjects were exposed in an environmental control chamber to all possible combinations of 2 atmospheric conditions (purified air and 0.6 ppm SO2), 2 temperatures (near 21 and 38 degrees C), and 2 levels of relative humidity (near 20 and 80%). Exposures involved 5 min of heavy exercise (target ventilation rate, 50 L/min) plus brief warm-up and cool-down periods. Body plethysmographic measurements and symptom questionnaire interviews were administered before and at the end of each exposure. Response was expressed in terms of change in airway size or change in intensity of symptoms during exposure. Atmospheric condition showed the most marked and significant overall effect on physiologic responses; temperature and humidity effects were also significant. High temperature and high humidity tended to mitigate the bronchoconstriction produced by 0.6 ppm SO2 exposure: group mean specific airway resistance approximately tripled at 21 degrees C and low humidity, but increased by less than 40% at 38 degrees C and high humidity. Temperature and humidity affected symptoms less consistently than physiologic responses, but in general, symptom responses paralleled physiologic responses.

Adult↗
PubMed1984

Concurrent polyarteritis nodosa and temporal arteritis.

A patient is described in which features of both giant cell arteritis and polyarteritis nodosa were present simultaneously. The case emphasises our lack of an aetiologic classification for arteritis and that on occasions typical clinical presentations may be misleading.

Aged↗
PubMed1984

Respiratory responses of humans exposed to an aerosol-gas pollutant mixture: multivariate contrast of a complex atmosphere to clean air and sodium chloride aerosol controls.

Data from a group of 20 subjects with normal baseline pulmonary function, who were exposed for 2 h to a test atmosphere containing a complex mixture of pollutants, have been contrasted with data from two other groups exposed to presumably non-toxic control atmospheres. Group 1 was exposed to clean air, group 2 was exposed to clean air containing sodium chloride aerosol at 270 micrograms m-3, and group 3 was exposed to the complex atmosphere containing sodium chloride (332 micrograms m-3) and zinc ammonium sulfate (23 micrograms m-3) aerosols plus nitrogen dioxide (0.5 ppm) and sulfur dioxide (0.5 ppm). These atmospheres (ranked according to the presumed relative toxicities of the components; clean air = 0, sodium chloride = 1, complex mixture = 2) were contrasted using multiple regression and partial correlation analyses. The effects of exposure to the complex gas-aerosol mixture on forced expiratory performance were not significantly different from those observed in subjects exposed to clean air or to sodium chloride aerosol.

Adolescent↗
PubMed1983

The atrio-ventricular node artery in the human heart.

The atrioventricular node artery is a major contributor to the arterial supply of the atrioventricular conducting pathway and is an important vessel in the pathogenesis of heart block. The terminal ramifications of this artery were studied in detail by serial sectioning techniques in 50 human infant hearts. The artery provided branches to the posterior interventricular septum in all hearts (100%) and to the interatrial septum in 22 hearts (44%). The vessel supplied the atrioventricular node in 45 hearts (90%) but it terminated before reaching the node in five (10%). It supplied the penetrating bundle in 32 hearts (64%). Alternative sources of arterial supply to the atrioventricular conducting pathway include: the first septal branch of the left anterior descending coronary artery; the descending septal artery; and anterior atrial branches. Although the arterial supply to this region of the heart is variable, it is possible to make hypothetical predictions of conducting tissue involvement in myocardial infarction of various types.

Arteries↗