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Biomedical subjects

H Gong

Publications and source records attributed to H Gong.

At least 127 records · Page 7Linked to original sources
PubMed1992

Pulmonary status of habitual cocaine smokers.

We determined the prevalence of respiratory symptoms and lung dysfunction in a large sample of habitual smokers of freebase cocaine ("crack") alone and in combination with tobacco and/or marijuana. In addition, we compared these findings with those in an age- and race-matched sample of nonusers of crack who did or did not smoke tobacco and/or marijuana. A detailed respiratory and drug use questionnaire and a battery of lung function tests were administered to (1) a convenience sample of 202 habitual smokers of cocaine (cases) who denied intravenous drug abuse and (2) a reference sample of 99 nonusers of cocaine (control subjects). The cocaine smokers (85% black) included the following: 68 never-smokers of marijuana, of whom 43 currently smoked tobacco and 25 did not, and 134 ever-smokers of marijuana (42 current and 92 former), of whom 92 currently smoked tobacco and 42 did not. The control subjects (96% black) included the following: 69 never-smokers of marijuana, of whom 26 currently smoked tobacco and 43 did not, and 30 ever-smokers of marijuana (18 current and 12 former), of whom 21 currently smoked tobacco and 9 did not. Cases smoked an average of 6.5 g cocaine per week for a mean of 53 months. The median time of the most recent use of crack prior to study was 19 days (range less than 1 to 180 days). After controlling for the use of other smoked substances, frequent crack use was associated with: (1) a high prevalence of at least occasional occurrences of acute cardiorespiratory symptoms within 1 to 12 h after smoking cocaine (cough productive of black sputum [43.7%], hemoptysis [5.7%], chest pain [38.5%], usually worse with deep breathing, and cardiac palpitations [52.6%]) and (2) a mild but significant impairment in the diffusing capacity of the lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Health effects of air pollution. A review of clinical studies.

The database for the acute health effects of common outdoor air pollutants is rapidly increasing but important gaps still exist. Greater technical efforts and innovative studies are required to adequately characterize health effects and understand the underlying mechanisms of toxicity. Controlled human exposures provide relevant data about short-term effects and complement animal and epidemiologic investigations. Except for possibly nitrogen dioxide, the clinical data for ozone, sulfur dioxide, and particulates (H2SO4) at contemporary levels indicate potentially untoward or adverse physiologic or clinical responses in healthy individuals and sensitive groups such as children, adolescents, and asthmatic patients. Exercise, duration, and other exposure factors may potentiate pollutant effects on symptoms, lung function, nonspecific bronchial reactivity, mucociliary clearance, and BAL markers of inflammation. Continued animal, clinical, and epidemiologic research of both short- and long-term health effects is clearly needed to support or limit future regulatory decisions regarding the quality of outdoor air.

Air Pollutants↗
PubMed1991

A nebulizer chronolog to monitor compliance with inhaler use.

The Lung Health Study is a 10-center 5-year clinical trial sponsored by the National Heart, Lung, and Blood Institute to evaluate the effectiveness of early intervention in chronic obstructive pulmonary disease (COPD). The specific objectives of the trial are to determine whether the accelerated decline in lung function characteristic of COPD and morbidity due to COPD can be reduced by special intervention at a relatively early stage in the evolution of the disease. Special intervention consists of a smoking-cessation program and the use of an inhaled bronchodilator to suppress airway hyperreactivity. The use of the inhaler canister is monitored every 4 months by canister weighing and, at two of the 10 centers, by an electronic recording device, the Nebulizer Chronolog. Among trial participants assigned the latter device, results from the first 4 months of the study indicate that only 52% of trial participants who were uninformed as to the nature of the chronolog used their inhaler at least twice daily as measured by the chronolog, compared with 87% as determined by self-report. Satisfactory or good compliance was achieved by 52% of these subjects as measured by the chronolog compared with 85% as assessed by canister weighing. Eighteen percent of uninformed participants "dumped" their inhalers within a 3-hour time period, contributing to the inaccuracy of canister weights as an indicator of compliance. Feedback of information to the participants from the chronolog improved the level of compliance and eliminated the "dumping" phenomenon. We conclude that, when accurate determinations of compliance are important, as in a drug trial, objective medication monitors should be considered. Electronic monitoring of inhaler use can provide valuable feedback, which encourages improved compliance.

Adult↗
PubMed1991

Marijuana smoking, pulmonary function, and lung macrophage oxidant release.

Pulmonary alveolar macrophages lavaged from tobacco smokers release increased levels of oxidants and have been implicated in the pathophysiology of emphysema. It is unknown whether lung macrophages recovered from marijuana smokers also liberate excessive levels of oxidants. To evaluate this possibility, pulmonary alveolar macrophages were obtained by bronchoalveolar lavage from nonsmokers, smokers of marijuana only, smokers of tobacco only, and smokers of tobacco plus marijuana. Spontaneous and stimulated superoxide anion release was measured by the superoxide dismutase-inhibitable reduction of ferricytochrome c. These findings were correlated with recent lung function tests. Superoxide anion production by macrophages, studies of small airway integrity (closing volume, closing capacity, and the slope of Phase III of the single-breath nitrogen washout curve), and evaluation of alveolar gas exchange (diffusing capacity of carbon monoxide) were similar in both nonsmokers and marijuana smokers. However, tobacco smoking was associated with both significantly higher levels of superoxide anion release by pulmonary alveolar macrophages and significant abnormalities of small airway function and alveolar diffusing capacity. Based on the results of this study, pulmonary alveolar macrophages of marijuana-only smokers do not produce increased amounts of oxidants when compared to macrophages of non-smoking subjects. This observation may account for the absence of abnormalities in small airway function and alveolar diffusing capacity in marijuana-only smokers, in contrast to the presence of such findings in smokers of tobacco, regardless of marijuana use.

Adult↗
PubMed1991

Enhanced alveolar monocytic phagocyte (macrophage) proliferation in tobacco and marijuana smokers.

We tested the hypothesis that enhanced cell division accounted for the augmented numbers of monocytic phagocytes with characteristics attributed to alveolar macrophages (AM) found in the lungs of habitual tobacco (T) and marijuana (M) smokers. The monocytic phagocytes, that is, alveolar macrophages, were obtained by bronchoalveolar lavage (BAL) from 12 nonsmoking subjects; 10 subjects who smoked T only (TS); 13 subjects who smoked M only (MS); and 6 smokers of both T and M (MTS). The replication of these cells was determined by measuring the incorporation of [3H]thymidine into the DNA of dividing cells and visually counting 2,000 cells on autoradiographically prepared cytocentrifuge cell preparations. This study demonstrated that the number of [3H]thymidine-labeled monocytic phagocytes with characteristics of alveolar macrophages from either TS or MS have a higher proliferative index compared to cells (macrophages) from nonsmokers, p less than 0.05 by one-way ANOVA. The total number of BAL macrophages that are in mitosis in TS (17.90 +/- 4.50 labeled AM x 10(3)/ml) or MTS (10.50 +/- 4.20 labeled AM x 10(3)/ml) are 18- and 10-fold greater, respectively, than the number obtained from nonsmokers (1.01 +/- 0.18 labeled AM x 10(3)/ml). Interestingly, the number of [3H]thymidine-labeled macrophages from MS (2.90 +/- 0.66 labeled AM x 10(3)/ml) are also greater than the number obtained from nonsmokers, although this is not statistically significant. The stimulus augmenting alveolar macrophage replication is as yet unknown but may likely be found in the T or M smoke.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Antimicrobial and respiratory burst characteristics of pulmonary alveolar macrophages recovered from smokers of marijuana alone, smokers of tobacco alone, smokers of marijuana and tobacco, and nonsmokers.

Rodent studies indicate that marijuana smoke can adversely affect the antimicrobial function of pulmonary alveolar macrophages (PAM). To evaluate whether marijuana smoke similarly affects human PAM, we compared phagocytosis, fungistatic/fungicidal activity, and superoxide anion (O2-) production of PAM recovered from marijuana smokers (MS), tobacco smokers (TS), marijuana and tobacco smokers (MTS), and nonsmokers (NS). Although PAM from the four groups were equally capable of ingesting Candida albicans, the macrophages from smokers differed from normal PAM in their ability to restrict intracellular yeast germination (ungerminated candida in smokers' PAM = 68 +/- 3% [46] versus NS = 54 +/- 6% [17], mean +/- SEM [n], p = 0.022). Despite heightened fungistatic activity, PAM from MS and TS destroyed significantly fewer intracellular yeast (28 +/- 2 and 29 +/- 2%, respectively) after 4 h than did macrophages recovered from NS (40 +/- 4%, p less than 0.05). Both basal and stimulated (dihydrocytochalasin B + opsonized zymosan or phorbol myristate acetate) O2- production were similar in PAM from MS and NS, but significantly increased in PAM from TS (p less than 0.05). Our findings indicate that marijuana smoking does not alter the phagocytic behavior or the respiratory burst of human PAM, but marijuana smoking does decrease the ability of human PAM to destroy ingested Candida albicans. These findings contrast with the effects of tobacco smoking, which not only decreases the fungicidal activity of human PAM but also increases their respiratory burst.

Adult↗
PubMed1990

Effects of oral cetirizine, a selective H1 antagonist, on allergen- and exercise-induced bronchoconstriction in subjects with asthma.

The protective efficacy of oral cetirizine, a selective and potent H1-receptor antagonist, against the immediate bronchoconstrictive response to allergen inhalation and exercise challenge was evaluated in 16 subjects with stable, predominantly mild asthma. The subjects underwent double-blind, crossover pretreatments in randomized order in two separate protocols with (1) three daily oral doses of 20 mg of cetirizine and placebo, followed by allergen inhalation, and (2) single oral doses of cetirizine (5, 10, and 20 mg), albuterol (4 mg), and placebo, followed by exercise with cold-air inhalation. Cetirizine failed to decrease bronchial sensitivity to inhaled allergen in eight of 10 subjects. Neither cetirizine nor albuterol uniformly inhibited exercise-induced bronchoconstriction. Serum concentrations of cetirizine were consistent with systemic H1-blocking activity. Modest bronchodilation occurred after administration of cetirizine and albuterol before exercise but not after the third dose of cetirizine in the allergen protocol. One subject developed moderate drowsiness during multiple dosing with cetirizine. Thus, cetirizine, in the doses studied, is not uniformly effective in preventing allergen- or exercise-induced bronchoconstriction. Histamine is one of many mediators participating in immediate asthmatic responses, and selective H1 antagonists do not completely block these airway events. However, cetirizine may still clinically benefit some patients with asthma, such as patients with allergic rhinitis or urticaria.

Administration, Oral↗
PubMed1990

"Auto-PEEP": incidence, magnitude, and contributing factors.

In patients receiving mechanical ventilation there occasionally occurs an unintentional positive end-expiratory pressure, known as auto-PEEP, a phenomenon that can easily go undetected. Potential adverse effects of auto-PEEP include misleading hemodynamic information, cardiopulmonary morbidity, or both. Our study was designed to evaluate the incidence of auto-PEEP, its magnitude, and factors influencing it in a university hospital. Every patient receiving ventilation was evaluated for controlled ventilation and auto-PEEP in medical and surgical intensive care units during a 3-month period. Expiration was stopped at the instant that the next inspiration would have been delivered. At this moment, when the pressures in the lung and the ventilator circuit had equilibrated, the level of auto-PEEP was systematically measured. Of 57 patients undergoing controlled mechanical ventilation, 27 (47%) had 1 to 6 cm H2O of auto-PEEP. The incidence of auto-PEEP increased significantly when the minute ventilation exceeded 18.4 L/min, the respiratory rate was higher than 27 breaths/min, or the set PEEP was greater than or equal to 10 cm H2O. Therefore, auto-PEEP is the result of several ventilator-related factors. Because auto-PEEP occurred in 47% of the patients in the study, routine monitoring for auto-PEEP in patients receiving controlled ventilation is recommended. Further studies of auto-PEEP and its clinical impact are warranted.

Adult↗
PubMed1989

Antibody-dependent cellular cytotoxicity mediated by lung macrophages: a comparison of two target cells.

Mononuclear cell-mediated cytotoxicity may be an important cellular immune function in host lung defense. Prior investigators have shown that lung macrophages participate in cell cytotoxicity which is antibody-dependent (ADCC). We tested the hypothesis that alveolar macrophages share some cell surface receptors for the Fc portion of IgG, i.e., Fc receptors, similar to those found on circulating monocytes in order to function in ADCC. Hence, ADCC mediated by autologous human blood monocytes and lung macrophages was studied by measuring the release of chromium-51 from prelabeled target erythrocytes coated with IgG. Alveolar macrophages were obtained from healthy adult subjects by bronchoalveolar lavage and tested against two different erythrocyte target cells to measure ADCC activity. Our results show significant activity by alveolar macrophages demonstrated against chicken erythrocytes at a target to effector cell ratio of 2:1 or 10:1 and with an antibody concentration of 1:100 or 1:400 (volume per volume, p less than 0.05, Student's test). However, when a peripheral blood monocyte specific target cell (human type B erythrocyte) was utilized, alveolar macrophages were not as capable of significant ADCC activity against these monocyte-specific target cells. The inability of lung macrophages to function in ADCC against other target cells (i.e., human type B erythrocytes) unlike the peripheral blood monocytes suggests that some Fc receptors are not shared. In other words, these different cell types share IgG receptors but differences in activity may be due to some changes in the Fc portions of IgG due to cellular differentiation. The use of these target cells may potentially be useful in functionally discriminating between two types of adherent autologous mononuclear cells (lung macrophages vs. blood monocytes).

Adult↗
PubMed1989

Effects of inhaled thiazinamium chloride on histamine-induced and exercise-induced bronchoconstriction.

The protective efficacy of aerosolized thiazinamium chloride (TC) against histamine-induced and exercise-induced bronchoconstriction was evaluated in 15 subjects with stable, mild asthma. Following reproducible bronchoprovocation with these stimuli, each subject underwent randomized, double-blind, crossover pretreatment with single doses of nebulized TC (300, 600, and 900 micrograms), placebo, and an active control drug (metaproterenol or cromolyn), followed by histamine or exercise challenge (two separate protocols). The results indicated that all doses of TC significantly blocked histamine-induced bronchoconstriction as compared with placebo. Overall, aerosolized TC was ineffective in blocking exercise-induced bronchoconstriction, although 900 micrograms TC tended to be more effective than placebo. Thiazinamium (900 micrograms) produced a modest bronchodilator effect. No clinically significant adverse effects related to TC occurred. We conclude that aerosolized TC is effective in attenuating histamine-induced but not exercise-induced bronchoconstriction in the doses studied. Further studies are warranted to evaluate the role of TC in asthma therapy.

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↗
PubMed1988

Diagnostic efficacy of a nasotracheal protected specimen brush in patients with suspected bacterial pneumonia.

The diagnostic yield and safety of a novel nasotracheal protected specimen brush (PSB) were evaluated in 15 nonintubated adult patients with suspected bacterial pneumonia. A double-catheter PSB was passed directly through the anesthetized nose and into the trachea without bronchoscopy or fluoroscopy. Endotracheal brushing was performed in less than 10 sec, and the brush was immediately processed for Gram staining and quantitative aerobic and anaerobic cultures. According to clinical follow-up and response to therapy, 11 episodes of bacterial pneumonia and five cases of nonbacterial lung disease were established. The PSB Gram stain confirmed lower respiratory sampling in all cases. The PSB cultures indicated respiratory pathogens in 9/11 (82%) cases of pneumonia, with greater than 10(3) colony-forming units (cfu)/ml in all but two specimens. All patients with pneumonia responded to specific antibiotics. All patients with nonbacterial disorders had PSB cultures of less than 10(3) CFU/ml, and their pulmonary processes improved without antibiotic therapy. The procedure was well tolerated, although two patients had transient bronchospasm or apnea. Experience with the nasotracheal PSB is limited, but the procedure appears to be a reliable and relatively safe alternative diagnostic method in selected patients with suspected bacterial pneumonia. Quantitative cultures are necessary to improve its diagnostic accuracy.

Adult↗
PubMed1988

Human and rabbit newborn lung macrophages have reduced anti-Candida activity.

Bronchoalveolar macrophages (BAM) protect the adult lung from low level microbial contamination. The antimicrobial activity of human newborn BAM is unknown. BAM were isolated from effluents of suctioned, intubated newborns and from bronchoalveolar lavage of healthy, nonsmoking adult volunteers. An in vitro cytologic slide assay was developed and used to ascertain: 1) inhibition of intracellular filamentation of Candida albicans (active yeast growth) and 2) killing + digestion of ingested C. albicans. The ability to restrict intracellular yeast filamentation was markedly different for human newborn versus adult BAM. Adult BAM were five times more effective in restricting intracellular filamentation of Candida compared to newborn cells (p less than 0.01). Nonfilamented ingested yeast were also handled differently by newborn and adult macrophages. Nonfilamented yeast were killed and digested by adult BAM at a rate that was 2.5 times above that noted in neonatal lung macrophages (p less than 0.005). However, no differences were found in the total number of killed + digested Candida within human newborn and adult BAM [adult = 32.4 +/- 10.5% (n = 5), newborn less than 1200 g = 39.6 +/- 16.8% (n = 8), and newborn greater than 1200 g = 30.2 +/- 11.1% (n = 16), mean +/- S.D.]. Neonatal BAM were able to destroy C. albicans at a level equivalent to adult cells because these newborn phagocytes allowed intracellular Candida to enter a state of active growth, thereby rendering the yeast more susceptible to killing and digestion. The anti-Candida activity noted in lung macrophages recovered from normal 1-day-old and adult rabbits was similar to that seen in human BAM.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗