***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: After experimental induction of acute bronchospasm in 8 subjects with clinical ly stable bronchial asthma , effects of 500 mg of smoked marijuana ( 2.0 per cent delta9-tetrahydrocannabinol ) on specific airway conductance and thoracic gas volume were compared with those of 500 mg of smoked placebo marijuana ( 0.0 per cent delta9-tetrahydrocannabinol ) , 0.25 ml of aerosolized saline , and 0.25 ml of aerosolized isoproterenol ( 1,250 mug ) . Bronchospasm was induced on 4 separate occasions , by inhalation of methacholine and , on four other occasions , by exercise on a bicycle ergometer or treadmill . Methacholine and exercise caused average decreases in specific airway conductance of 40 to 55 per cent and 30 to 39 per cent , respectively , and average increases in thoracic gas volume of 35 to 43 per cent and 25 to 35 per cent , respectively . After methacholine-induced bronchospasm , placebo marijuana and saline inhalation produced minimal changes in specific airway conductance and thoracic gas volume , whereas 2.0 per cent marijuana and isoproterenol each caused a prompt correction of the bronchospasm and associated hyperinflation . After exercise-induced bronchospasm , placebo marijuana and saline were followed by gradual recovery during 30 to 60 min , whereas 2.0 per cent marijuana and isoproterenol caused an immediate reversal of exercise-induced asthma and hyperinflation OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity Abstract Normal volunteers with previous marihuana smoking experience inhaled the total smoke from 3.23 mg per kilogram of marihuana , using a bag-in-box technic . R and omly , nine received marihuana containing a high ( 2.6 per cent ) , and eight a low ( 1.0 per cent ) concentration of delta-9 tetrahydrocannabinol .  Physiologic variables were monitored before and for 20 minutes after smoking . In the high-dose group the heart rate increased 28 per cent . Concomitantly , airway resistance , measured in a body plethysmograph , fell 38 per cent ; the functional residual capacity remained unchanged ( ± 50 ml ) throughout , and specific airway conductance increased 44 per cent . Flow-volume loops showed a 45 per cent increase in flow rate at 25 per cent of vital capacity . The low-dose group showed no increase in heart rate but significant , if lesser changes , in airways dynamics . Carbon dioxide sensitivity , measured by rebreathing remained unchanged in both groups . Marihuana smoke , unlike cigarette smoke , causes bronchodilatation Abstract Acute pulmonary physiologic effects of smoked marijuana and oral Δ9-tetrahydrocannabinol were investigated in 32 healthy , experienced male marijuana smokers . After smoking of marijuana ass Ten young , healthy male volunteers smoked a marihuana cigarette with 2.5 % δ9-THC and a THC-exhausted placebo cigarette . The marihuana administration was associated with an increase in heart rate , elevation of systolic blood pressure , conjunctival reddening and specific airway conductance increase ; time perception and Automated Digit Symbol Substitution Test performance were impaired . Diastolic blood pressure and attention measured by the Continuous Performance Task were not affected . The placebo preparation produced a subjective pleasant “ high ” but no physiologic effects nor performance change . The “ high ” induced by the active preparation was often rated as unpleasant Effects on airway dynamics , heart rate , and the central nervous system of various doses of delta9-tetrahydrocannabinol administered in a r and om , double blind fashion using a Freon-propelled , metered-dose nebulizer were evaluated in 11 healthy men and 5 asthmatic subjects . Effects of aerosolized delta9-tetrahydrocannabinol were compared with aerosolized placebo and isoproterenol and with 20 mg of oral and smoked delta9-tetrahydrocannabinol . In the normal subjects , after 5 to 20 mg of aerosolized delta9-tetrahydrocannabinol , specific airway conductance increased immediately , reached a maximum ( 33 to 41 per cent increase ) after 1 to 2 hours , and remained significantly greater than placebo values for 2 to 3 hours . The bronchodilator effect of aerosolized delta9-tetrahydrocannabinol was less than that of isoproterenol after 5 min , but significantly greater than that of isoproterenol after 1 to 3 hours . The magnitude of bronchodilatation after all doses of aerosolized delta9-tetrahydrocannabinol was comparable , but 5 mg of delta9-tetrahydrocannabinol caused a significantly smaller increase in heart rate and level of intoxication than the 20-mg dose . Smoked delta9-tetrahydrocannabinol produced greater cardiac and intoxicating effects than either aerosolized or oral delta9-tetrahydrocannabinol . Side effects of aerosolized delta9-tetrahydrocannabinol included slight cough and /or chest discomfort in 3 of the 11 normal subjects . Aerosolized delta9-tetrahydrocannabinol caused significant bronchodilatation in 3 of 5 asthmatic subjects , but caused moderate to severe bronchoconstriction associated with cough and chest discomfort in the other 2 . These findings indicate that aerosolized delat9-tetrahydrocannabinol , although capable of causing significant bronchodilatation with minimal systemic side effects , has a local irritating effect on the airways , which may make it unsuitable for therapeutic use To assess the possible role of daily smoking of marijuana in the development of chronic obstructive pulmonary disease ( COPD ) , we evaluated the effect of habitual use of marijuana with or without tobacco on the age-related change in lung function ( measured as FEV1 ) in comparison with the effect of nonsmoking and regular tobacco smoking . A convenience sample of 394 healthy young Caucasian adults ( 68 % men ; age : 33 + /- 6 yr ; mean + /- SD ) including , at study entry , 131 heavy , habitual smokers of marijuana alone , 112 smokers of marijuana plus tobacco , 65 regular smokers of tobacco alone , and 86 nonsmokers of either substance were recruited from the greater Los Angeles community .  FEV1 was measured in all 394 participants at study entry and in 255 subjects ( 65 % ) on up to six additional occasions at intervals of > or = 1 yr ( 1.7 + /- 1.1 yr ) over a period of 8 yr . R and om-effects models were used to estimate mean rates of decline in FEV1 and to compare these rates between smoking groups . Although men showed a significant effect of tobacco on FEV1 decline ( p < 0.05 ) , in neither men nor women was marijuana smoking associated with greater declines in FEV1 than was nonsmoking , nor was an additive effect of marijuana and tobacco noted , or a significant relationship found between the number of marijuana cigarettes smoked per day and the rate of decline in FEV1 . We conclude that regular tobacco , but not marijuana , smoking is associated with greater annual rates of decline in lung function than is nonsmoking . These findings do not support an association between regular marijuana smoking and chronic COPD but do not exclude the possibility of other adverse respiratory effects 
    Output:
    
Short-term exposure to marijuana is associated with bronchodilation .
Physiologic data were inconclusive regarding an association between long-term marijuana smoking and airflow obstruction measures .
Long-term marijuana smoking is associated with increased respiratory symptoms suggestive of obstructive lung disease