Panlobular emphysema is associated with COPD disease severity: A study of emphysema subtype by computed tomography.

BACKGROUND: Computed tomography has the potential to inform COPD prognosis. We sought to determine associations of emphysema phenotype with clinical parameters including lung function, inflammatory markers, and quality of life. METHODS: Participants of this single-center observational cohort (n = 83) were 40-80 years old, had ≥10 pack-year smoking, and a diagnosis of COPD confirmed by spirometry. All participants had available historic chest CT scans which were systematically reviewed by a single expert radiologist and scored for emphysema subtype, extent, and distribution. Associations between radiographic findings and clinical parameters were determined. RESULTS: Median age of participants was 72 years, median smoking 40 pack-years, and median FEV1 59% predicted. 84% of the participants had radiographic emphysema. Of those, 26% had panlobular emphysema (PLE), 68% centrilobular emphysema (CLE), and 6% paraseptal emphysema (PSE). As compared to the participants with no radiographic emphysema, the presence of PLE-dominant emphysema was associated with a lower BMI (P = 0.012) and greater extent of emphysema (P = 0.014). After adjusting for age, sex, and pack-years smoking history, PLE was associated with greater airflow obstruction by FEV1% (48% vs 71%, P = 0.005), greater symptom burden by CAT score (18 vs 9, P = 0.015), worse quality of life by SGRQ score (43 vs 22, P = 0.025), and more systemic inflammation by erythrocyte sedimentation rate (P = 0.001). CLE- or PSE-dominant emphysema were not similarly associated with clinical features or symptom burden. CONCLUSIONS: The presence of PLE-dominant emphysema was associated with greater extent of emphysema, greater airflow obstruction, increased respiratory symptoms, worse quality of life, and systemic inflammation. Further investigation is indicated to explore the pathogenesis of the PLE phenotype and the prognostic and treatment implications of PLE.

Hypoxia inducible factor promotes murine allergic airway inflammation and is increased in asthma and rhinitis.

BACKGROUND: New therapies are necessary to address inadequate asthma control in many patients. This study sets out to investigate whether hypoxia-inducible factor (HIF) is essential for development of allergic airway inflammation (AAI) and therefore a potential novel target for asthma treatment. METHODS: Mice conditionally knocked out for HIF-1ß were examined for their ability to mount an allergic inflammatory response in the lung after intratracheal exposure to ovalbumin. The effects of treating wild-type mice with either ethyl-3,4-dihydroxybenzoate (EDHB) or 2-methoxyestradiol (2ME), which upregulate and downregulate HIF, respectively, were determined. HIF-1α levels were also measured in endobronchial biopsies and bronchial fluid of patients with asthma and nasal fluid of patients with rhinitis after challenge. RESULTS: Deletion of HIF-1ß resulted in diminished AAI and diminished production of ovalbumin-specific IgE and IgG(1) . EDHB enhanced the inflammatory response, which was muted upon simultaneous inhibition of vascular endothelial growth factor (VEGF). EDHB and 2ME antagonized each other with regard to their effects on airway inflammation and mucus production. The levels of HIF-1α and VEGF increased in lung tissue and bronchial fluid of patients with asthma and in the nasal fluid of patients with rhinitis after challenge. CONCLUSIONS: Our results support the notion that HIF is directly involved in the development of AAI. Most importantly, we demonstrate for the first time that HIF-1α is increased after challenge in patients with asthma and rhinitis. Therefore, we propose that HIF may be a potential therapeutic target for asthma and possibly for other inflammatory diseases.

Long-term efficacy of tiotropium in relation to smoking status in the UPLIFT trial.

UPLIFT (Understanding Potential Long-Term Improvements in Function with Tiotropium), a 4-yr trial of tiotropium in chronic obstructive pulmonary disease, allowed for assessment of smoking status on long-term responses to maintenance bronchodilator therapy. 5,993 patients were randomised (tiotropium/placebo). Lung function, St George's Respiratory Questionnaire, exacerbations and adverse events were followed. Patients were characterised as continuing smokers (CS), continuing ex-smokers (CE), or intermittent smokers (IS) based on self-reporting smoking behaviour. 60%, 14% and 26% of patients were CE, CS and IS, respectively. The rate of forced expiratory volume in 1 s (FEV(1)) decline for placebo patients was most rapid in CS (-52+/-4, -37+/2 and -23+/2 mL.yr(-1) in CS, IS, and CE, respectively). Tiotropium did not alter FEV(1) decline, but was associated with significant improvements in pre- and post-bronchodilator FEV(1) over placebo that persisted throughout the 4-yr trial for each smoking status (pre-bronchodilator: 127, 55 and 97 mL at 48 months in CS, IS and CE, respectively; p< or =0.0003). Tiotropium reduced exacerbation risk in CS (HR (95% CI) 0.80 (0.67-0.95)), in CE (0.85 (0.79-0.92)) and trended towards significance in IS (0.89 (0.79-1.00)). At 4 yrs, St George's Respiratory Questionnaire for tiotropium patients improved the most in CS (-4.63 units, p = 0.0006) and the least in IS (-0.60 units, p = 0.51), [corrected] compared with control. Tiotropium provided long-term benefits irrespective of smoking status, although differences among categories were observed.

Tiotropium as a first maintenance drug in COPD: secondary analysis of the UPLIFT trial.

The aim of the present study was investigate the long-term effect of tiotropium as first maintenance respiratory medication in chronic obstructive pulmonary disease (COPD). A 4-yr, randomised, multicentre, double-blind, parallel-group, placebo-controlled trial (Understanding Potential Long-term Impacts on Function with Tiotropium (UPLIFT) was conducted. Analysis focused on the effect of tiotropium versus matching placebo in the 810 (13.5%) COPD patients not on other maintenance treatment (long-acting beta-agonists, inhaled corticosteroids, theophyllines or anticholinergics) at randomisation. Spirometry, health-related quality of life (St George's Respiratory Questionnaire (SGRQ) score), exacerbations of COPD and mortality were also analysed. 403 patients (mean+/-sd age 63+/-8 yrs, post-bronchodilator forced expiratory volume in 1 s (FEV(1)) 53+/-12% predicted) received tiotropium and 407 (64+/-8 yrs of age, post-bronchodilator FEV(1) 51+/-12% pred) received placebo. Post-bronchodilator FEV(1) decline was 42+/-4 mL.yr(-1) in the tiotropium group and 53+/-4 mL.yr(-1) in the placebo group (p = 0.026). At 48 months, the morning pre-dose FEV(1) was 134 mL higher in the tiotropium group compared to the placebo group (p<0.001). SGRQ total score declined more slowly in the tiotropium group (difference of 1.05+/-0.34 units.yr(-1); p = 0.002). This was particularly significant for the impact (difference of 1.08+/-0.37 units.yr(-1); p = 0.004) and activity (1.44+/-0.40 units.yr(-1); p<0.001) domains, but not for symptoms (0.26+/-0.50 units.yr(-1); p = 0.6). At 48 months, the difference in total score was 4.6 units (p<0.001) with tiotropium compared to placebo. In patients with COPD who are not on maintenance therapy, tiotropium is associated with significant benefits in disease progression.

A computer-aided diagnosis system for quantitative scoring of extent of lung fibrosis in scleroderma patients.

OBJECTIVES: To evaluate an improved quantitative lung fibrosis score based on a computer-aided diagnosis (CAD) system that classifies CT pixels with the visual semi-quantitative pulmonary fibrosis score in patients with scleroderma-related interstitial lung disease (SSc-ILD). METHODS: High-resolution, thin-section CT images were obtained and analysed on 129 subjects with SSc-ILD (36 men, 93 women; mean age 48.8±12.1 years) who underwent baseline CT in the prone position at full inspiration. The CAD system segmented each lung of each patient into 3 zones. A quantitative lung fibrosis (QLF) score was established via 5 steps: 1) images were denoised; 2) images were grid sampled; 3) the characteristics of grid intensities were converted into texture features; 4) texture features classified pixels as fibrotic or non-fibrotic, with fibrosis defined by a reticular pattern with architectural distortion; and 5) fibrotic pixels were reported as percentages. Quantitative scores were obtained from 709 zones with complete data and then compared with ordinal scores from two independent expert radiologists. ROC curve analyses were used to measure performance. RESULTS: When the two radiologists agreed that fibrosis affected more than 1% or 25% of a zone or zones, the areas under the ROC curves for QLF score were 0.86 and 0.96, respectively. CONCLUSIONS: Our technique exhibited good accuracy for detecting fibrosis at a threshold of both 1% (i.e. presence or absence of pulmonary fibrosis) and a clinically meaningful threshold of 25% extent of fibrosis in patients with SSc-ILD.

Bronchodilator responsiveness in patients with COPD.

The degree of acute improvement in spirometric indices after bronchodilator inhalation varies among chronic obstructive pulmonary disease (COPD) patients, and depends upon the type and dose of bronchodilator and the timing of administration. Acute bronchodilator responsiveness at baseline was examined in a large cohort of patients with moderate-to-very-severe COPD participating in the Understanding Potential Long-term Impacts on Function with Tiotropium (UPLIFT) trial, a 4-yr randomised double-blind trial evaluating the efficacy of 18 mug tiotropium daily in reducing the rate of decline in lung function. After wash-out of respiratory medications, patients received 80 mug ipratropium followed by 400 mug salbutamol. Spirometry was performed before and 90 min following ipratropium administration. The criteria used for forced expiratory volume in one second (FEV(1)) responsiveness were: >or=12% increase over baseline and >or=200 mL; >or=15% increase over baseline; and >or=10% absolute increase in the percentage predicted value. Of the patients, 5,756 had data meeting the criteria for analysis (age 64.5 yrs; 75% male; baseline FEV(1) 1.10 L (39.3% predicted) and forced vital capacity (FVC) 2.63 L). Compared with baseline, mean improvements were 229 mL in FEV(1) and 407 mL in FVC. Of these patients, 53.9% had >or=12% and >or=200 mL improvement in FEV(1), 65.6% had >or=15% improvement in FEV(1), and 38.6% had >or=10% absolute increase in FEV(1) % pred. The majority of patients with moderate-to-very-severe chronic obstructive pulmonary disease demonstrate meaningful increases in lung function following administration of inhaled anticholinergic plus sympathomimetic bronchodilators.

Circulating fibronectin to C-reactive protein ratio and mortality: a biomarker in COPD?

The balance between inflammatory and repair processes is important in maintaining lung homeostasis in chronic obstructive pulmonary disease (COPD). The aim of the present study was to determine whether or not an integrated index of a biomarker involved in inflammation, C-reactive protein (CRP), and another involved in wound repair, fibronectin, may be a good measure to predict clinical outcomes in COPD. Circulating blood levels of CRP and fibronectin were measured in 4,787 individuals with mild-to-moderate COPD who were prospectively followed for >7 yrs after blood collection as part of the Lung Health Study. To assess the balance between repair and inflammation, a simple ratio was calculated by dividing fibronectin levels by CRP levels and a Cox proportional hazards model was used to determine the relationship between this ratio and all-cause and disease-specific causes of mortality. The relationship between the fibronectin to CRP ratio and all-cause mortality was L-shaped. There was an exponential decay in the adjusted hazard function (i.e. the risk of mortality) as the ratio decreased until a value of 148 was reached, beyond which point the hazard function did not change significantly. Similar results were observed for the risk of coronary and cardiovascular mortality. Circulating fibronectin to CRP ratio is significantly associated with all-cause mortality of COPD patients. However, in contrast to other biomarkers, the relationship appears to be L-shaped (and not linear), suggesting a threshold at approximately 150. While promising, future studies are needed to validate this simple index as a biomarker in COPD.

Histopathologic and molecular alterations in bronchial epithelium in habitual smokers of marijuana, cocaine, and/or tobacco.

BACKGROUND: Tobacco smoking has been observed to cause molecular alterations in bronchial epithelium that antedate the development of lung carcinoma. The rising prevalence of marijuana and cocaine use among young adults in the United States prompted us to investigate whether similar molecular and histopathologic alterations occur in habitual smokers of marijuana and/or cocaine who may or may not also smoke tobacco. METHODS: Bronchoscopy was performed in 104 healthy volunteer subjects, including 28 nonsmokers and 76 smokers of one or more of the following substances: marijuana, tobacco, and/or cocaine. Bronchial mucosa biopsy specimens and brushings were analyzed for histopathologic changes, for immunohistopathologic expression of intermediate or surrogate end-point markers that are linked to an increased risk of cancer (Ki-67 [a marker of cell proliferation], epidermal growth factor receptor, p53, Her-2/neu [also known as erbB-2 and ERBB2], globular actin, and abnormal DNA ploidy). Reported P values are two-sided. RESULTS: Smokers of any one substance or of two or more substances exhibited more alterations than nonsmokers in five to nine of the 10 histopathologic parameters investigated (all P < .05), and they exhibited more molecular abnormalities than nonsmokers. Differences between smokers and nonsmokers were statistically significant (all P < or = .01) for Ki-67, epidermal growth factor receptor, globular actin, and DNA ploidy. There was general agreement between the presence of molecular abnormalities and histopathologic alterations; however, when disagreement occurred, the molecular abnormalities (e.g., Ki-67 and epidermal growth factor receptor) were more frequently altered (all P < or = .01). CONCLUSIONS: These findings suggest that smoking marijuana and/or cocaine, like tobacco smoking, exerts field cancerization effects on bronchial epithelium, which may place smokers of these substances at increased risk for the subsequent development of lung cancer.

Pneumocystis with normal chest X-ray film and arterial oxygen tension. Early diagnosis in a patient with the acquired immune deficiency syndrome.

A patient with Kaposi's sarcoma and the acquired immune deficiency syndrome became acutely febrile and dyspneic. Although chest roentgenograms and findings from arterial blood oxygenation studies were normal, bronchoscopy disclosed heavy Pneumocystis carinii infection. The patient was treated with trimethoprim-sulfamethoxazole with a rapid clinical response. It has been distinctly unusual to diagnose Pneumocystis without roentgenographic or blood gas abnormalities. Pneumocystis infection probably occurs as a wide spectrum of disease ranging from subclinical infection to frank pneumonitis. In the appropriate clinical setting, clinically significant Pneumocystis infection may be diagnosed despite the absence of an infiltrate or hypoxemia and early treatment may be beneficial.

Mentholated cigarette use and lung cancer.

BACKGROUND: Menthol combustion produces carcinogenic compounds such as benzo[a]pyrenes. Mentholated cigarettes are much more commonly smoked by black individuals than by white individuals. The incidence of lung cancer is much higher (60%) in black men than in white men, but it differs little by race in women. We examined the association of mentholated cigarette use with lung cancer in men and women because mentholated cigarette use could help to explain the higher incidence rate of lung cancer in black men than in white men. METHODS: The study population consisted of 11,761 members of the Northern California Kaiser Permanente Medical Care Program, Oakland (5771 men and 3990 women), aged 30 to 89 years, who underwent a multiphasic health checkup in 1979 through 1985 and reported that they were current cigarette smokers who had smoked for at least 20 years. Data were collected about current cigarette brand, duration of mentholated cigarette use, and other smoking characteristics. Follow-up for incident lung cancer cases (n = 318) was carried out through 1991. RESULTS: The relative risk of lung cancer associated with mentholation compared with nonmentholated cigarettes was 1.45 in men (95% confidence interval, 1.03 to 2.02) and it was 0.75 in women (95% confidence interval, 0.51 to 1.11), adjusted for age, race, education, number of cigarettes smoked per day, and duration of smoking. Further adjustment for tar content and self-reported smoking intensity characteristics did not substantially alter the estimate of relative risk. A graded increase in risk of lung cancer with increasing duration of mentholated cigarette use was present in men. CONCLUSION: This study suggests that there is an increased risk of lung cancer associated with mentholated cigarette use in male smokers but not in female smokers.

Smoked marijuana as a cause of lung injury.

In many societies, marijuana is the second most commonly smoked substance after tobacco. While delta9-tetrahydrocannabinol (THC) is unique to marijuana and nicotine to tobacco, the smoke of marijuana, like that of tobacco, consists of a toxic mixture of gases and particulates, many of which are known to be harmful to the lung. Although far fewer marijuana than tobacco cigarettes are generally smoked on a daily basis, the pulmonary consequences of marijuana smoking may be magnified by the greater deposition of smoke particulates in the lung due to the differing manner in which marijuana is smoked. Whereas THC causes modest short-term bronchodilation, regular marijuana smoking produces a number of long-term pulmonary consequences, including chronic cough and sputum, histopathologic evidence of widespread airway inflammation and injury and immunohistochemical evidence of dysregulated growth of respiratory epithelial cells, that may be precursors to lung cancer. The THC in marijuana could contribute to some of these injurious changes through its ability to augment oxidative stress, cause mitochondrial dysfunction, and inhibit apoptosis. On the other hand, physiologic, clinical or epidemiologic evidence that marijuana smoking may lead to chronic obstructive pulmonary disease or respiratory cancer is limited and inconsistent. Habitual use of marijuana is also associated with abnormalities in the structure and function of alveolar macrophages, including impairment in microbial phagocytosis and killing that is associated with defective production of immunostimulatory cytokines and nitric oxide, thereby potentially predisposing to pulmonary infection. In view of the growing interest in medicinal marijuana, further epidemiologic studies are needed to clarify the true risks of regular marijuana smoking on respiratory health.

The safety of anticholinergic bronchodilators for the treatment of chronic obstructive pulmonary disease.

INTRODUCTION: Poorly absorbable quaternary ammonium-inhaled muscarinic antagonists both as the short-acting ipratropium and as long-acting (12 - 24 h) agents (tiotropium, glycopyrronium, aclidinium and umeclidinium) have all demonstrated statistically and clinically significant efficacy in chronic obstructive pulmonary disease compared with placebo. However, controversy has arisen concerning the safety of this class of agents principally regarding their association with both fatal and nonfatal cardiovascular toxicity. AREAS COVERED: The safety of both ipratropium and the long-acting muscarinic antagonists is reviewed with a major emphasis on potential cardiovascular toxicity, based on published clinical trials data and results of analyses of pooled data, meta-analyses, and observational studies. Since glycopyrronium, aclidinium, and umeclidinium have become available only relatively recently, more emphasis will be placed on the more extensive literature concerning the safety of the older anticholinergic compounds, the short-acting ipratropium, and the long-acting tiotropium in its dry powder formulation, as well as its newer soft mist inhaler delivery device. EXPERT OPINION: Pooled analyses and meta-analyses of randomized controlled trials (RCTs) of tiotropium in both its dry powder and soft mist formulations, as well as some observational studies, have implicated this agent as increasing the risk of nonfatal and fatal cardiovascular events. However, the most robust evidence based on large-scale randomized controlled trials (RCTs) of relatively long duration specifically designed to evaluate the cardiovascular safety of tiotropium have not confirmed these safety concerns. Because of the relatively limited amount of safety data for the newer long-acting muscarinic antagonists compared to the far more extensive experience with tiotropium, it will be important to accumulate additional safety information from post-marketing pharmacovigilance for these newer agents.

Reversal of human lymphocyte beta-adrenoceptor desensitization by glucocorticoids.

To investigate the effect of glucocorticoids on beta-agonist-induced desensitization, we studied the effect of a single intravenous dose of methylprednisolone (2 mg/kg) on beta-receptor density and affinity in lymphocytes from four normal and four mildly asthmatic subjects at the end of 3 to 5 wk of terbutaline therapy and from four normal subjects taking no other drug. Terbutaline decreased (-)[3H]-dihydroalprenolol binding sites by 53% in normal and by 42% in asthmatic subjects. Methylprednisolone restored the number of binding sites to levels statistically indistinguishable from the preterbutaline values in both groups of subjects. In subjects not exposed to terbutaline beforehand there was no significant alteration in receptor density after methylprednisolone, nor in normal lymphocytes incubated in vitro for 90 min with hydrocortisone (10(-5)M). No significant change in the dissociation constant was observed in any situation. A single intravenous dose of methylprednisolone reverses terbutaline-induced down-regulation of beta-adrenoceptors. This may provide a mechanism for the beneficial effect of steroids in restoring catecholamine responsiveness in asthmatic subjects.

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.

Environmental tobacco smoking, mutagen sensitivity, and head and neck squamous cell carcinoma.

Although active tobacco smoking has been considered a major risk factor for head and neck cancer, few studies have evaluated environmental tobacco smoke (ETS) and its interaction with mutagen sensitivity on the risk of head and neck cancer. We investigated the relationship between ETS and head and neck cancer in a case-control study of 173 previously untreated cases with pathologically confirmed diagnoses of squamous cell carcinoma of the head and neck and 176 cancer-free controls at Memorial Sloan-Kettering Cancer Center between 1992 and 1994. A structured questionnaire was used to collect ETS exposure and other covariates including a history of active tobacco smoking and alcohol use. ETS measures include a history of ETS exposure at home and at workplace. The associations between passive smoking and head and neck cancer were analyzed by Mantel-Haenszel methods and logistic regression models. Additive and multiplicative models were used to evaluate effect modifications between ETS and mutagen sensitivity. The crude odds ratio (OR) for ETS exposure was 2.8 [95% confidence intervals (CI), 1.3-6.0]. Controlling for age, sex, race, education, alcohol consumption, pack-years of cigarette smoking, and marijuana use, the risk of squamous cell carcinoma of the head and neck was increased with ETS (adjusted OR, 2.4; 95% CI, 0.9-6.8). Dose-response relationships were observed for the degree of ETS exposure; the adjusted ORs were 2.1 (95% CI, 0.7-6.1) for those with moderate exposure and 3.6 (95% CI, 1.1-11.5) for individuals with heavy exposure (P for trend = 0.025), in comparison with those who never had ETS exposures. These associations and the dose-response relationships were still present when the analysis was restricted to nonactive smoking cases and controls (crude OR, 2.2; 95% CI, 0.6-8.4). Crude odds ratios were 1.8 for those with moderate ETS exposure and 4.3 for individuals with heavy ETS exposure among nonsmoking cases and controls (P for trend = 0.008). More than multiplicative interaction was suggested between passive smoking and mutagen sensitivity. This study suggests that ETS exposure may increase the risk of head and neck cancer with a dose-response pattern. Our analysis indicated that passive smoking may interact with mutagen sensitivity and other risk factors to increase the risk of head and neck cancer. Our results need to be interpreted with caution because of potential residual confounding effects of active tobacco smoking and other methodological limitations. Future large-scale studies are warranted to confirm our findings.

Marijuana use and increased risk of squamous cell carcinoma of the head and neck.

Marijuana is the most commonly used illegal drug in the United States. In some subcultures, it is widely perceived to be harmless. Although the carcinogenic properties of marijuana smoke are similar to those of tobacco, no epidemiological studies of the relationship between marijuana use and head and neck cancer have been published. The relationship between marijuana use and head and neck cancer was investigated by a case-control study of 173 previously untreated cases with pathologically confirmed diagnoses of squamous cell carcinoma of the head and neck and 176 cancer-free controls at Memorial Sloan-Kettering Cancer Center between 1992 and 1994. Epidemiological data were collected by using a structured questionnaire, which included history of tobacco smoking, alcohol use, and marijuana use. The associations between marijuana use and head and neck cancer were analyzed by Mantel-Haenszel methods and logistic regression models. Controlling for age, sex, race, education, alcohol consumption, pack-years of cigarette smoking, and passive smoking, the risk of squamous cell carcinoma of the head and neck was increased with marijuana use [odds ratio (OR) comparing ever with never users, 2.6; 95% confidence interval (CI), 1.1-6.6]. Dose-response relationships were observed for frequency of marijuana use/day (P for trend <0.05) and years of marijuana use (P for trend <0.05). These associations were stronger for subjects who were 55 years of age and younger (OR, 3.1; 95% CI, 1.0-9.7). Possible interaction effects of marijuana use were observed with cigarette smoking, mutagen sensitivity, and to a lesser extent, alcohol use. Our results suggest that marijuana use may increase the risk of head and neck cancer with a strong dose-response pattern. Our analysis indicated that marijuana use may interact with mutagen sensitivity and other risk factors to increase the risk of head and neck cancer. The results need to be interpreted with some caution in drawing causal inferences because of certain methodological limitations, especially with regard to interactions.

Silicosis due to intentional inhalation of abrasive scouring powder. Case report with long-term survival and vasculitic sequelae.

Silicosis due to inhalation of abrasive scouring powder is now an unusual event. We report a nonindustrial case of acute silicosis due to intentional inhalation of commercial, silica-containing scouring powder. This case is unique in that the patient had a 20 year survival (after onset of symptoms) with typical roentgenographic and histopathologic changes of silicosis, and evidence of immune complex disease in extrapulmonary tissues.

Sites of airway dilatation in asthma following inhaled versus subcutaneous terbutaline. Comparison of physiologic tests with radionuclide lung images.

In 12 asthmatic subjects with mild to severe airways obstruction, we compared the relative magnitude and sites of airway dilatation of a beta-adrenergic stimulant administered by different routes. Specific airway conductance (SGaw), peak expiratory flow, the sum of the absolute volume of isoflow and residual volume as a percentage of total lung capacity (capacity of isoflow) and the ratio of maximal expiratory flow at 50 per cent of vital capacity breathing 80 per cent helium-20 per cent oxygen to that breathing air (ratio Vmax50) were determined before and after the administration of aerosolized terbutaline (0.5 mg), subcutaneous terbutaline (0.5 mg) or placebo. Increases in SGaw and peak expiratory flow of greater than or equal to 25 per cent were considered to indicate significant dilatation of central airways; increases in ratio Vmax50 of greater than or equal to 0.10 and decreases in capacity of isoflow of greater than or equal to 10 per cent were assumed to reflect dilatation of peripheral airways. In addition, radioaerosol and radioxenon lung imaging was performed to determine the relationship between changes in lung imaging patterns and changes in physiologic indices in response to bronchodilator therapy. Placebo caused little change in lung function or lung imaging. After inhaled terbutaline, SGaw and peak expiratory flow increased greater than or equal to 25 per cent in seven subjects, ratio Vmax50 increased greater than or equal to 0.10 in only three subjects, capacity of isoflow decreased greater than or equal to 10 per cent in only one subject, radioaerosol images showed less central deposition in nine subjects and radioxenon images showed improved distribution and/or washout of xenon in five subjects. After the administration of subcutaneous terbutaline, SGaw and peak expiratory flow increased greater than or equal to 25 per cent in 10 subjects, ratio Vmax50 increased greater than or equal to 0.10 in 10 subjects, capacity of isoflow decreased greater than or equal to 10 per cent in 11 subjects, and radioaerosol and xenon images showed improvement in 11 and eight subjects, respectively. These findings are consistent with the action of inhaled terbutaline mainly on large airways and of subcutaneous terbutaline on both large and small airways. Although reduced central radioaerosol deposition correlated well with physiologic evidence of large airway dilatation, improvement in xenon distribution and washout could be attributed to dilatation of either large and/or small airways.