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Biomedical subjects

M S Simmons

Publications and source records attributed to M S Simmons.

At least 37 records · Page 2Linked to original sources
PubMed1992

Metered-dose inhaler adherence in a clinical trial.

We studied patterns of inhaler usage in a sample of participants from two centers in the Lung Health Study clinical trial. The inhaler, containing either ipratropium bromide or a placebo, was prescribed to be taken as two inhalations three times daily. For 4 months we recorded adherence by both self-report (n = 95) and canister weight change (n = 70). We compared these results with data obtained from a microprocessor monitoring device, the Nebulizer Chronolog (NC), which records the date and time of each inhaler actuation. Seventy-three percent of the participants reported using the inhaler an average of three times daily; however, NC data showed that only 15% of the participants actually used the inhaler an average of 2.5 or more times per day. Canister weight overestimated adherence because only 62% of the NC sets contained the prescribed two actuations. Fourteen percent showed a pattern of actuation of their inhalers more than 100 times in a 3-h interval. We interpret this usage pattern to reflect deliberate emptying of inhalers to appear to be in good compliance with the prescribed program. We conclude that self-report and weighing of inhaler canisters overestimate adherence to the prescribed regimens. Furthermore, a substantial number of monitored inhaler users appear to deliberately dump their medication prior to follow-up visits.

Administration, Inhalation↗
PubMed1991

Pulmonary dysfunction in advanced liver disease: frequent occurrence of an abnormal diffusing capacity.

PURPOSE: Abnormalities in pulmonary function have been reported in association with chronic liver disease of varied etiology. The aim of this study was to better define the frequency and nature of these abnormalities in patients who were being evaluated for liver transplantation. PATIENTS AND METHODS: We performed a battery of pulmonary function tests and chest radiographs in 116 consecutive patients (50 men, 66 women; aged 19 to 70 years, mean 44.6 years) with severe advanced liver disease who were hospitalized specifically for evaluation for possible orthotopic liver transplantation and were able to perform technically satisfactory tests. In 17 patients, quantitative whole-body technetium-99m macroaggregated albumin perfusion scanning was also performed for assessment of possible right-to-left shunting through intrapulmonary vascular dilatations. RESULTS: The most commonly affected test of lung function was the single-breath diffusing capacity for carbon monoxide (DLCO), which was abnormal in 48%, 45%, and 71% of patients who never smoked, former smokers, and current smokers, respectively. Ventilatory restriction was noted in 25% of all patients, airflow obstruction (reduced ratio of forced expiratory volume in 1 second to forced vital expiratory volume in 1 second to forced vital capacity) in only 3%, and a widened alveolar-arterial oxygen gradient in 45%. Diffusion impairment was accompanied by a restrictive defect in only 35% of the patients and by an abnormally widened alveolar-arterial oxygen gradient in 60%. When diffusion impairment was accompanied by an oxygenation defect, it was also associated with a significantly increased right-to-left shunt fraction (mean 24.9%) assessed from quantitative whole-body perfusion imaging. On the other hand, isolated diffusion impairment unaccompanied by significant hypoxemia (noted in approximately a third of the patients with a reduced DLCO) was not associated with evidence of significant intrapulmonary shunting (mean right-to-left shunt fraction 6.7%). CONCLUSIONS: Most patients with advanced liver disease have one or more types of abnormality in lung function, a reduced DLCO being the single most common functional defect. Mechanisms accounting for the abnormality in gas transfer may include intrapulmonary vascular dilatations, diffuse interstitial lung disease, pulmonary vaso-occlusive disease, and/or ventilation-perfusion imbalance.

Adult↗
PubMed1990

Dental patient reaction to electrocardiogram screening.

Ninety-one patients receiving routine dental treatment at the University of Minnesota School of Dentistry participated in an electrocardiogram screening study. The purpose of the study was to evaluate patient reaction to electrocardiogram screening in a dental school clinic. The vast majority of patients indicated the test was easy and did not intrude on the dental appointment. Most of the patients reported that the test was a valuable service and should be available in the dental office. None of the patients indicated that the tests should not be performed in the dental office. Few patients expressed any significant concern or anxiety about the test either before or after it was completed. Twenty-six percent (24/91) of the patients were found to have a cardiac arrhythmia; however, most of these were nonserious arrhythmias (18/24) and would not have had an impact on planned dental procedures. Six patients were identified with arrhythmias that required medical referral before dental treatment was started.

Adolescent↗
PubMed1990

Ventilatory and diffusion abnormalities in potential heart transplant recipients.

Few data are available concerning pulmonary function in patients with severe chronic congestive heart failure. Of 315 patients evaluated for potential cardiac transplantation at UCLA, 132 underwent pulmonary function tests. The latter patients had severe heart failure with a mean left ventricular ejection fraction of 19 percent and mean cardiac index of 2.1 L/min/m2. Diffusion impairment either alone or combined with restrictive and/or obstructive ventilatory defects occurred in 67 percent of the patients evaluated. Diffusion impairment occurred as the sole abnormality in 31 percent of the patients and in combination with a restrictive ventilatory defect in 21 percent. A reduction in diffusing capacity has not been previously described as a frequent finding in patients with chronic congestive heart failure. In contrast to other studies involving patients with acute heart failure, obstructive ventilatory defects were uncommon. None of the lung function abnormalities was associated with smoking status, prior drug use, chest roentgenographic changes, hemodynamic findings, or clinical features, including duration of congestive heart failure. The mechanism for the diffusion impairment is unclear but could be due to chronic passive congestion with pulmonary fibrosis and/or recurrent pulmonary emboli. Recognition of diffusion impairment as a common finding in patients with severe chronic congestive heart failure who are candidates for heart transplantation is important for proper interpretation of possible post-transplant changes in diffusing capacity due to other causes.

Adult↗
PubMed1989

Effects of chlorinated benzenes on diatom fatty acid composition and quantitative morphology. I. 1,2,4-Trichlorobenzene.

Cells of the diatom Cyclotella meneghiniana were exposed in a closed system to 0.245 ppm 1,2,4-trichlorobenzene. Response to this chlorinated benzene was monitored over a period of 5 days by quantitative ultrastructure and fatty acid percent composition. Over the time period examined, 41 significant morphological changes and 12 significant changes in fatty acid composition were observed. Autophagic-like vacuoles were frequently observed, indicating lysis of cellular constituents. In general, there was an increase in the C20:5 fatty acid, which may be indicative of photosynthetic impairment, since this fatty acid probably substitutes for linolenic acid in diatoms. The most significant numbers of changes were observed after 8 hr of exposure to this lipophilic toxicant, and these changes occurred in membranous organelles. It is suggested that the daily photoperiodic variation in lipid content of phytoplankton may be an important consideration in evaluating effects of lipophilic toxicants.

Chlorobenzenes↗
PubMed1989

Effects of chlorinated benzenes on diatom fatty acid composition and quantitative morphology. II. 1,3,5-Trichlorobenzene.

Cells of the diatom Cyclotella meneghiniana were exposed in a closed system to 0.245 ppm 1,3,5-trichlorobenzene. Response of the diatom was measured by quantitative ultrastructure and fatty acid percent composition over a 5-day period. During that time, 28 significant morphological and 13 significant fatty acid percent composition changes occurred. Autophagic-like vacuoles were observed consistently through the sampling periods. In comparison with exposure to 1,2,4-trichlorobenzene, 1,3,5-trichlorobenzene exerts fewer effects in the parameters studied, and these effects were observed most frequently in membranous components during the initial eight hours of exposure. It is suggested that the amount of cellular lipid and the relative reactivity of the isomer are responsible for the observed effects.

Chlorobenzenes↗
PubMed1989

Effects of chlorinated benzenes on diatom fatty acid composition and quantitative morphology. III. 1,2,3-Trichlorobenzene.

Cells of the diatom Cyclotella meneghiniana were exposed in a closed system to 0.245 ppm 1,2,3-trichlorobenzene. Response of the diatom was measured by quantitative ultrastructure and fatty acid percent composition over a 5-day period. During that time, 35 significant morphological and 12 fatty acid percent composition changes occurred. The most pronounced morphological change that occurred was a significant increase in lipid volume. In addition, changes were observed in vacuolar relative volume, suggesting that the tonoplast became more permeable. Fewer significant changes were observed in fatty acid percent composition upon exposure to this isomer. However, there was a consistent increase in oleic acid (C18:1). The observed changes in morphological and fatty acid percent composition were uniformly distributed with time after the first hour of exposure. Results support the hypothesis that increased lipid stores may alter the timing of response to lipophilic toxicants.

Chlorobenzenes↗
PubMed1989

Effects of chlorinated benzenes on diatom fatty acid composition and quantitative morphology. IV. Pentachlorobenzene and comparison with trichlorobenzene isomers.

Cells of the diatom Cyclotella meneghiniana were exposed in a closed system to 0.095 ppm pentachlorobenzene over a period of 5 days. Changes in fatty acid and morphological percent composition were monitored to determine the effect of the toxicant. The greatest morphological change observed was an increase in lipid volume. Most morphological changes occurred in the 1 hour and 5 day sampling periods. Few changes in morphological characteristics or fatty acid percent composition were observed at eight hours, when the cells were in the dark. The C18:1 and C20:5 fatty acids were most variable with exposure to pentachlorobenzene. Results suggest that at sublethal doses, lipophilic toxicants exert effects that are biphasic. That is, immediately measurable effects are observed in the cells that include increases in storage products and changes in membranous organelles. Long-term effects are postulated to be the result of mobilization of lipophilic toxicants that have partitioned into lipid stores and are more available when lipids are metabolized. Although pentachlorobenzene has a higher octanol/water partition coefficient, it appears to exert fewer cellular changes than any trichlorobenzene isomer.

Chlorobenzenes↗
PubMed1989

Intraindividual variability in serial measurements of DLCO and alveolar volume over one year in eight healthy subjects using three independent measuring systems.

To evaluate intraindividual and between-machine variability in DLCO, one technician performed triplicate measurement of DLCO in eight healthy subjects on three consecutive days using three different systems (Collins [C], Gould [G], SRL [S]) on five separate occasions over the course of 1 yr. For each subject and machine, we calculated the coefficient of variation (CV) of the DLCO and its associated alveolar volume (VA) and inspiratory vital capacity (IVC) over the five different measurement periods using the mean value for each period. CV (in %) for DLCO in each of the eight subjects for each machine varied from 2.4 to 7.1% for machine C, 4.1 to 10.5% for machine G, and 2.5 to 8.7% for machine S. Two-way ANOVA showed significant differences in CV for DLCO and IVC but not for VA across subjects (p less than 0.01) and for DLCO, VA, and IVC across machines (p less than 0.03): CV for DLCO was higher for G than for C or S; CV for VA and IVC was lower for C than for G or S. Multiple regression did not show a significant relationship between within-individual CV for DLCO and that for VA or IVC. We conclude that variability in DLCO measurements is affected by both subject and machine, but, at least in healthy cooperative subjects, it does not appear to be affected by variability in VA or IVC. For the average subject and the two less variable machines we tested, DLCO measurements could vary within the same subject as much as +/- 9.6% (two-tailed 95% confidence interval) with repeated measurements over 1 yr.

Adult↗
PubMed1988

Metered-dose inhaler usage in subjects with asthma: comparison of Nebulizer Chronolog and daily diary recordings.

The Nebulizer Chronolog (NC) is a portable electronic device that attaches to standard metered-dose inhalers (MDIs) and records and stores the date and time of each MDI actuation. We evaluated the long-term performance of the NC and compared its data to concurrent recordings of self-administered MDI usage in daily diaries. Eighty-three subjects with asthma were evaluated during a 7 1/2-month panel study of air pollution effects. Although 44 (53%) of the NCs developed a malfunction during the study, the average total (+/- SD) percentage of useful days with functioning NCs was still 86 +/- 18% (median 93%). The agreement between the daily diary and NC recordings was very high, that is, 50 (67%) of 75 subjects had perfect agreement. Eighteen subjects with over or under diary reporting were detected. We conclude that the NC is an effective, objective, accurate, and continuous monitor of daily MDI usage despite some remediable technical problems. The NC can facilitate the evaluation of short- and long-term medication usage patterns and compliance issues in MDI-related research and clinical settings.

Adolescent↗
PubMed1987

Dental erosion secondary to ethanol-induced emesis.

Case reports within the dental literature have attributed dental erosion to many factors. Severe dental erosion from chronic vomiting, induced by ethanol abuse, has not been previously documented. This article reports such a history and reviews appropriate intervention by the dental practitioner.

Adult↗
PubMed1987

Respiratory effects of cocaine "freebasing" among habitual users of marijuana with or without tobacco.

Use of cocaine by smoking its alkaline precursor ("freebasing") has become increasingly prevalent. Recent studies of small numbers of cocaine users suggest that freebasing frequently causes cough, dyspnea, and abnormalities in diffusing capacity (DCO), although these findings could have been due to concomitant use of other drugs. We therefore evaluated the relationship between cocaine use by freebasing and chronic respiratory symptoms and lung dysfunction in a large sample of habitual smokers of marijuana with or without tobacco who denied intravenous drug abuse. The findings suggested that, among habitual marijuana smokers, "moderate" cocaine smoking damaged both large and small airways, as reflected by functional changes that were independent of concomitant marijuana use and appeared to be synergistic with the effects of tobacco. On the other hand, no adverse influence of cocaine smoking on the pulmonary microcirculation was demonstrated in our sample of freebase users.

Adult↗
PubMed1986

Impaired exercise performance and pulmonary function in elite cyclists during low-level ozone exposure in a hot environment.

We evaluated the effects of low concentrations of ozone on the exercise performance and pulmonary function of 17 top-caliber endurance cyclists under conditions simulating competition and realistic temperature (31 degrees C). Each subject was randomly exposed to filtered air (FA), 0.12 and 0.20 ppm O3 on separate days in an environmental chamber. Each subject attempted to maintain submaximal exercise on a cycle ergometer equivalent to approximately 70% of maximal oxygen consumption (VO2max) for 60 min, followed by incremented (maximal) exercise until exhaustion. During submaximal exercise, average minute ventilation (VE) (89 L/min), VO2 (51 ml/min/kg or 72% VO2max), work load (260 W), and work time (57 min) were similar across all exposures. During maximal exercise, average peak VE (150 L/min), VO2 (68 ml/min/kg), work load (382 W), and ride time (263 s) were similar between 0.12 ppm O3 and FA. However, significant reductions in peak VE (18%), VO2 (16%), tidal volume (22%), work load (8%), and ride time (30%) occurred in 0.20 ppm O3 compared with those in FA. Postexercise decrements in forced expired volume in one second (FEV1) averaged 5.6% and 21.6% in 0.12 and 0.20 ppm O3, respectively. Ozone-related symptoms were mild in 0.12 ppm O3 but intensified and probably limited maximal performance in 13 subjects in 0.20 ppm O3. Changes in carbon monoxide diffusing capacity (adjusted for alveolar volume) were not significant across exposures. Nine subjects showed histamine hyperresponsiveness (i.e., greater than 20% decrease from the control postdiluent FEV1) after exposure to 0.20 ppm O3 as compared with 1 subject in 0.12 ppm O3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

The need for psychiatric-dental liaison in the treatment of bulimia.

During dental examinations 38% of 66 outpatients with bulimia were found to have evidence of significant enamel erosion, and chronicity of vomiting was significantly associated with erosion. Liaison with colleagues in dentistry is necessary when working with bulimic patients.

Adolescent↗
PubMed1986

Bronchodilator effects of caffeine in coffee. A dose-response study of asthmatic subjects.

Although caffeine is a universal drug and has multiple pharmacologic and physiologic actions in man, there are surprisingly few objective data about its effect on pulmonary function. We conducted a short-term, double-blind, randomized crossover study in nine asthmatic adults who ingested decaffeinated coffee containing varying amounts of added caffeine (mean of 0.2,2.5,5.6, and 7.2 mg/kg of body weight) on different days. The subjects also ingested decaffeinated coffee and aminophylline (200 mg) on a separate day of study. Baseline and post-drug determinations of serum levels of caffeine and theophylline, forced expired volume and flow, specific airway conductance (Gaw/VL), vital signs, and reported symptoms were obtained. Peak increases in serum caffeine concentrations (mean, 12.4 micrograms/ml +/- 1.5 micrograms/ml) occurred 45 minutes following the highest dose of caffeine (7.2 mg/kg), whereas the peak theophylline level (mean 3.8 micrograms/ml +/- 0.4 micrograms/ml) occurred 90 minutes following oral administration of aminophylline (mean theophylline, 2.6 mg/kg). Comparable peak increases in the forced expiratory volume in one second (FEV1), the forced expiratory flow during the middle half of the forced vital capacity (FEF25-75%), and Gaw/VL occurred at 120 minutes following aminophylline and the highest dose of caffeine, indicating that caffeine is an effective bronchodilator but is only 40 percent as active as an equivalent molar dose of theophylline. Regression analysis revealed statistically significant dose-response relationships between peak increases in serum caffeine concentrations and increases in FEV1, FEF25-75%, and Gaw/VL from baseline values. These findings have diagnostic and therapeutic implications regarding the use of caffeine prior to tests of pulmonary function and as a dietary agent, alone or in combination with theophylline.

Administration, Oral↗
PubMed1984

Acute and subacute bronchial effects of oral cannabinoids.

The bronchodilating activity of oral cannabinoids was evaluated in three double-blind experiments that involved the study of dose-response and interactive relationships and the potential development of tolerance. Data indicated that delta 8-tetrahydrocannabinol (delta 8-THC), cannabinol (CBN), and cannabidiol (CBD) in maximal doses of 75 mg, 1200 mg, and 1200 mg, respectively, did not induce significant dose-related physiologic effects in experienced marijuana smokers. delta 8-THC (75 mg) was, however, associated with bronchodilation, tachycardia, and peak highs less than that after delta 9-tetrahydrocannabinol (delta 9-THC). The combinations of CBN and CBD with low-dose delta 9-THC (5 mg) did not induce significant bronchodilation but did exert interactive effects on heart rate and "high." A 20-day study of daily delta 9-THC (20 mg), CBN (600 mg), and CBD (1200 mg) did not indicate tolerance or reverse tolerance to any drug. We conclude that delta 9-THC and, to a lesser extent, delta 8-THC, have acute bronchodilator activity but that CBN, CBD, and their combinations do not provide effective bronchodilation. The daily use of delta 9-THC was not associated with clinical tolerance.

Administration, Oral↗