Expiratory and inspiratory chest computed tomography and pulmonary function tests in cigarette smokers

This study evaluated small airway dysfunction and emphysematous destruction of lung parenchyma in cigarette smokers, using chest expiratory high-resolution computed tomography (HRCT) and pulmonary function tests (PFT). The degree of emphysematous destruction was classified by visual scoring (VS) and the average HRCT number at full expiration/full inspiration (E/I ratio) calculated in 63 male smokers and 10 male nonsmokers (group A). The Brinkman smoking index (BI), defined as cigarettes x day(-1) x yrs, was estimated. Sixty-three smokers were divided into three groups by PFT: group B1 (n=7), with normal PFT; group B2 (n=21), with diffusing capacity of the lung for carbon monoxide (DL,CO) > or = 80% predicted, forced expiratory volume in one second (FEV1) < 80% pred and/or residual volume (RV) > 120% pred; and group B3 (n=35), with DL,CO < 80% pred, FEV1 < 80% pred and/or RV > 120% pred. Heavy smokers (BI > or = 600) (n=48) showed a significant increase in emphysema by both VS and E/I. E/I was significantly elevated in both group B2 (mean+/-SD 0.95+/-0.05) and B3 (0.96+/-0.06) compared with group B1 (0.89+/-0.03). VS could not differentiate group B2 (3.9+/-5.0) from B1 (1.1+/-1.6). These findings suggest that the expiration/inspiration ratio reflects hyperinflation and airway obstruction, regardless of the functional characteristics of emphysema, in cigarette smokers.

Smoking, nicotine and psychiatric disorders: evidence for therapeutic role, controversies and implications for future research

Researchers interested in investigating the possible therapeutic effects and the mechanisms of action of nicotine in neuropsychiatric disorders face a social-scientific-ethical dilemma. This dilemma comprises three components: (1) the known addictive potential of nicotine makes careful evaluation of the therapeutic potential of this compound socially unattractive; (2) the potential misuse of scientifically determined data by the tobacco 'lobby' creates ethical concerns; and (3) the possible confusion between the differential effects of nicotine in human smokers versus non-smokers creates difficulties in study designs in voluntary human subjects. Therefore, it is imperative that, at the onset of this review, the authors stress that they do not advocate cigarette-smoking as a route of nicotine intake under any circumstances on the basis that controlled dosing of nicotine may be of potential benefit in some neuropsychiatric disorders. In this article, we review the psychopharmacology of nicotine and its effects in a variety of neuropsychiatric disorders including schizophrenia, depression, anxiety and Tourette's syndrome. Possible mechanisms of action of nicotine directly or indirectly via its interaction with other neurotransmitter systems (i.e. serotonin, dopamine and noradrenaline) in relation to its potential role in these disorders are discussed. It is postulated that new drugs may need to be developed that selectively interact with nicotinic receptors without addiction potential.

Smoking cravings are reduced by self-massage

BACKGROUND

Attempts at smoking cessation have been correlated with severe withdrawal symptoms, including intense cigarette cravings, anxiety, and depressed mood. Massage therapy has been shown to reduce anxiety and stress hormones and improve mood.

METHOD

Twenty adult smokers (M age = 32.6) were randomly assigned to a self-massage treatment or a control group. The treatment group was taught to conduct a hand or ear self-massage during three cravings a day for 1 month.

RESULTS

Self-reports revealed lower anxiety scores, improved mood, and fewer withdrawal symptoms. In addition, the self-massage group smoked fewer cigarettes per day by the last week of the study.

CONCLUSIONS

The present findings suggest that self-massage may be an effective adjunct treatment for adults attempting smoking cessation to alleviate smoking-related anxiety, reduce cravings and withdrawal symptoms, improve mood, and reduce the number of cigarettes smoked.

Periodontal probing depth and subgingival temperature in smokers and non-smokers

The aim of this study was to investigate the difference in subgingival temperature between smokers and non-smokers at different probing depths, and the effect of probing depth on subgingival temperature for smokers and non-smokers. 20 smokers and 20 non-smokers, with adult periodontitis, and retained upper anterior teeth were included. Initially sublingual temperatures were recorded, followed by subgingival temperature, pocket probing depth, and bleeding upon probing measurements at 3 buccal points at probing depths of 2, 3, 4, 5, and 6 mm for each of the anterior teeth. Sublingual temperatures were consistently higher than subgingival temperatures. The subgingival temperature measurements of pockets which bled upon probing, were subtracted from the sublingual temperature to produce temperature differentials (delta T), independent of individual body temperature, that were compared between smokers and non-smokers. The relationship between probing depth and delta T was examined in, and between, smokers and non-smokers for bleeding sites. delta T was found to decrease linearly with the increase of probing depth, suggesting a subsequent increase of subgingival temperature. Smokers were found to have significantly increased delta T(suggesting lower subgingival temperatures) compared to non-smokers, at probing depths of 2, 3, 4, and 5 mm. The differences in delta T for sites 6 mm in depth were not statistically significant between the 2 groups. It is concluded that for maxillary buccal anterior sites, there is a decrease of temperature differentials with an increase of probing depth at bleeding sites for both smokers and non-smokers. Smokers had higher temperature differentials compared to non-smokers, at probing depths of 2, 3, 4 and 5 mm.

Effects of menstrual phase on reactivity to nicotine

The possible impact of menstrual phase upon reactivity to nicotine was investigated in 12 healthy women smokers. Controlled doses of nicotine were administered via an intranasal aerosol delivery device to overnight-deprived women smokers in four hormonally verified menstrual phases. Physiological, biochemical, and subjective measures were collected. Cycle-related symptomatology differed significantly across phase, with lowest values during the mid-follicular phase. No significant differences were found for baseline variables, including withdrawal measures. Nicotine increment was stable across phase, confirming reliability of the dosing method. No significant menstrual phase differences were found for physiological, subjective, or biochemical responses to nicotine. Pending investigations conducted over longer intervals, in a wider variety of subjects; findings suggest that for this type of study, complex strategies to control for menstrual-cycle phase effects may be unnecessary.

Effects of smoking cessation on blood pressure and heart rate variability in habitual smokers

We investigated the effects of 1-week of smoking cessation on ambulatory blood pressure, heart rate, and heart rate variability in 39 normotensive male habitual smokers (mean+/-SEM, 32.5+/-1.0 years). The ambulatory blood pressure, heart rate, and ECG R-R intervals were measured during a 24-hour period with a portable recorder (TM-2425) on the last day of 1-week smoking and nonsmoking periods. The order of the 2 periods was randomized. In the smoking period, the subjects were instructed to smoke cigarettes according to their usual smoking patterns. A power-spectral analysis of R-R intervals was performed to obtain the low-frequency (LF) and high-frequency (HF) components. The percentage of differences between adjacent normal R-R intervals >50 milliseconds (pNN50) was used as a time-domain measure of heart rate variability. The 24-hour ambulatory blood pressure was significantly lower in the nonsmoking period than in the smoking period, by 3.5+/-1.1 mm Hg systole [P<0. 01] and by 1.9+/-0.7 mm Hg diastole [P<0.05], whereas the nighttime blood pressure did not differ significantly between the 2 periods. The 24-hour heart rate was significantly lower in the nonsmoking period than in the smoking period, by 7.3+/-1.0 beats/min (P<0.0001). The pNN50 and the 24-hour HF component were significantly higher in the nonsmoking period than in the smoking period (P<0.0001 for each). The plasma norepinephrine and epinephrine concentrations were significantly lower in the nonsmoking period than in the smoking period (P<0.05 for each). These results demonstrate the substantial and immediate benefits of smoking cessation on these cardiovascular indices.

Appropriate selection of GTR therapy

The appropriate application of guided tissue regeneration (GTR) therapy demands both diagnostic and technical acumen. This article discusses the presurgical considerations that must be evaluated before surgical entry and treatment. A diagnostic system for the evaluation of maxillary molar furcation involvements also is presented.

Subjective and physiological effects of intravenous nicotine and cocaine in cigarette smoking cocaine abusers

The subjective and physiological effects of intravenously administered cocaine and nicotine were compared in 10 cigarette-smoking cocaine abusers. Subjects abstained from smoking at least 8 h before each session. Under double blind conditions, subjects received placebo, cocaine (10, 20, and 40 mg/70 mg), or nicotine (0.75, 1.5, 3.0 mg/70 kg) in mixed order. Physiological and subjective data were collected before and repeatedly after each intravenous drug administration. Subjects also completed a drug versus money multiple-choice procedure in which they chose between that day's drug and 44 monetary values. Both drugs increased blood pressure and heart rate and decreased skin temperature. Nicotine showed a more rapid onset of subjective effects than cocaine. Overall, although both cocaine and nicotine increased subjective ratings of "drug effect", "rush", "good effects", "liking", "high", and "stimulated", only nicotine increased ratings of "bad effects" and "jittery". Although the highest nicotine dose produced greater effects than the highest cocaine dose on most subjective measures, the highest cocaine dose produced somewhat greater ratings of drug liking. At doses that produced comparable ratings of drug effect (40 mg/70 kg cocaine versus 1.5 mg/70 kg nicotine), cocaine produced significantly greater good effects, whereas nicotine produced greater bad effects. All three cocaine doses and the intermediate and high nicotine doses were frequently categorized as producing effects similar to those of cocaine or amphetamine. The drug versus money measure showed that the highest cocaine dose was worth twice as much as the highest nicotine dose. Thus, intravenous cocaine and nicotine can be differentiated by their subjective and reinforcing effects.

Oxidative stress in smokers supplemented with vitamin C

The ability of vitamin C supplement to influence lipid peroxidation and pulmonary function tests in healthy smokers was investigated. In this randomized double blind controlled trail, 56 smokers (S) received either 500 mg of vitamin C (C) or placebo (P) daily for 4 weeks. All completed the trial. Both groups were comparable and the number of cigarettes smoked were C: 14.2 +/- 1.8 and P: 18.3 +/- 2.0 pack-years. Plasma vitamin C concentrations increased significantly (p < 0.005) only in the group supplemented with vitamin C. Lipid peroxidation measured by breath pentane output (BPO) (C: 7.5 +/- 1.4 vs P: 7.0 +/- 1.3 pmol.kg-1.min-1) and plasma HPLC-separated malondialdehyde (MDA) (C: 0.58 +/- 0.05 vs P: 0.47 +/- 0.05 nmol.ml-1) were not significantly different between the 2 groups at baseline and did not change after four weeks of vitamin C supplementation (BPO: C: 5.3 +/- 0.9 vs P: 5.5 +/- 0.9 pmol.kg-1.min-1; HPLC-MDA: C: 0.50 +/- 0.07 vs P: 0.42 +/- 0.07 nmol.ml-1). No changes were detected in pulmonary function tests even in heavy smokers. Therefore, 4 week supplementation with 500 mg of vitamin C did not change lipid peroxidation indices and had no effect on pulmonary function tests.

Whole-body bone mineral measurements in 15-year-old Swedish adolescents

Bone mineral area (BA), total bone mineral content (TBMC) and total bone mineral density (TBMD) were assessed by dual-energy X-ray absorptiometry (DXA) in 396 randomly selected, healthy 15-year-old Swedish boys and girls. The influence of body size, pubertal development, physical activity level (PAL), total energy expenditure (TEE), dietary intake of energy, calcium and vitamin D, and alcohol and smoking habits on TBMC and TBMD were examined in bi- and multivariate analyses. In bivariate analyses BA, TBMC and TBMD showed strong correlations with weight, height and TEE in both sexes. In boys but not in girls these bone variables were significantly correlated with dietary intakes of energy, calcium and vitamin D. No significant correlations were found between PAL and the three bone variables. In multivariate analyses with TBMC as dependent variable BA, height, weight and Tanner stages explained 88% and 87% of the variance in boys and girls respectively. In similar analyses with TBMD as dependent variable the corresponding figures were 50% and 54%. The major part of the variance in all these models was explained by BA, and only a few percent by all the other independent variables. No significant reduction was found when TEE or daily intakes of calcium or vitamin D were introduced into the models. These results illustrate the importance of including BA, weight and height as independent variables in regression models of TBMC to avoid spurious associations with other variables in the analyses. The results may also indicate that in normal Swedish adolescents environmental factors such as dietary intake of nutrients play a minor role as determinants of bone mineralization. High levels of physical activity and bone mineral measures possibly explain the lack of significant correlations between these variables and do not imply a lack of association.

Relationship between smoking and colonic involvement in inflammatory bowel disease

The effects of smoking on the onset and clinical course of inflammatory bowel disease (IBD) have been widely debated. Although smoking appears to have a clearly unfavorable effect on the course in Crohn's Disease (CD), the relationship between smoking and localization of the disease is less clear.

AIM

To evaluate, in our group of patients, the relationship between smoking and the development of ulcerative colitis (UC) or CD, and between smoking and the localization of CD in the large bowel or in other sites.

PATIENTS AND METHODS

The smoking habits of 171 patients at the time of diagnosis were assessed with a questionnaire. Subjects were classified into three subgroups as smokers, nonsmokers and ex-smokers. Current smokers were grouped according to their level of consumption as those who smoked fewer than or more than 10 cigarettes per day. A total of 161 patients were studied (UC n = 69, CD n = 92). Patients with CD were divided into those with colonic disease and those with no colonic involvement. We evaluated the relationship between smoking and the form of IBD, localization (colonic or noncolonic) and the presence of perianal disease (PAD) in CD. The results were analyzed with the chi-squared test.

RESULTS

Smoking was more frequent in patients with CD than in those with UC (72.8% vs 31.9%). Among patients with CD, more patients without colonic involvement were smokers (84.6% vs 64.2%). However, among patients with CD involving the colon, smoking was significantly more common (64.2%) than among patients who had UC (31.9%).

CONCLUSIONS

Our findings confirm a relationship between smoking and CD. Smoking seems to be associated with some degree of protection of the colonic mucosa, especially in heavy smokers.

Scotopic sensitivity: relation to age, dietary patterns, and smoking status

PURPOSE

Although previous data suggest that rod-mediated sensitivity decreases with age, this decrease may be insignificant when only healthy individuals younger than 65 years are considered. In this study, we assess the relationship between age and scotopic sensitivity loss in subjects younger than 65 years to determine whether scotopic sensitivity losses can be detected when confounding factors are considered (including iris color, smoking status, and dietary patterns) and a large sample size is used.

METHODS

A total of 121 subjects (aged 20 to 63 years) were tested under dark-adapted (scotopic) conditions. Scotopic sensitivity was measured as absolute thresholds to a 2.8 degree, 550-nm test presented at 6 degrees in the temporal hemiretina. Stimuli were presented in Maxwellian view.

RESULTS

When all the subjects were considered together, there was a slight nonsignificant trend for scotopic sensitivity to decline with age (p < 0.11). This tendency was largely driven by the older (45 to 63 years) past and never smokers and was statistically significant (p < 0.024 and p < 0.05, respectively) when those two groups were analyzed separately. Scotopic sensitivity for the younger (20 to 44 years) past, current, and never smokers did not decline with age. When all the variables were considered in a general model, dietary intake of vitamin E explained a significant amount of the variation in scotopic sensitivity (p < 0.03). No relationships were found between scotopic sensitivity and iris color.

CONCLUSIONS

Age-related losses in scotopic sensitivity before age 65 are slow. Moreover, individual variations in scotopic sensitivity for younger subjects is minimal, even in the presence of dramatic stressors such as long-term, heavy exposure to cigarette smoke. These data suggest that measurements of scotopic sensitivity may not be good indicators of the retinal health of individuals younger than 65 years.

Increased perception of airway narrowing in patients with mild asthma

To compare the perception of airway narrowing of nonasthmatic subjects with those having wheeze or mild asthma (doctor-diagnosed), the relationship between FEV1 and breathlessness was examined in 123 subjects from a general population sample. Scores for breathlessness, using the Borg scale, were recorded before and after inhaling incremental doses of methacholine to a maximal dose of 196 mcmol or a maximum change in FEV1 of 50%. A history of asthma symptoms, including wheeze in the previous 12 months, and doctor-diagnosed asthma was obtained by questionnaire. At any given level of FEV1 there was wide variation in Borg scores between subjects, however median Borg scores and the mean slope of Borg score on FEVI was greater in the asthmatic subjects or those with wheeze compared with nonasthmatic subjects or those without wheeze. In both nonasthmatic and asthmatic subjects, those with airway hyperresponsiveness had increased maximum symptom scores and maximum changes in FEVI, but similar Borg scores relative to change in FEVI, compared with those without hyperresponsiveness. We conclude that the perception of mild and moderate degrees of airway narrowing varies widely between individuals but is increased in subjects with a history of mild asthma or wheeze in the last 12 months, independently of airway responsiveness.

Prediction of overall pulmonary function loss in relation to the 3-D dose distribution for patients with breast cancer and malignant lymphoma

PURPOSE

To predict the changes in pulmonary function tests (PFTs) 3-4 months after radiotherapy based on the three-dimensional (3-D) dose distribution and taking into account patient- and treatment-related factors.

METHODS

For 81 patients with malignant lymphoma and breast cancer, PFTs (VA, VC, FEV1 and TL,COc) were performed prior to and 3-4 months after irradiation and dose-effect relations for early changes in local perfusion, ventilation and air-filled fraction were determined using correlated CT and SPECT data. The 3-D dose distribution of each patient was converted into four different dose-volume parameters, i.e. the mean dose in the lung and three overall response parameters (ORPs, which represent the average local injury over the complete lung). ORPs were determined using the dose-effect relations for early changes in local perfusion, ventilation and air-filled fraction. Correlation coefficients were calculated between these dose-volume parameters and the changes in PFTs. In addition, the impact of the variables chemotherapy (MOPP/ABV and CMF), tamoxifen, smoking, age and gender on the relation between the mean lung dose and the relative changes in PFTs following radiotherapy was studied using multiple regression analysis.

RESULTS

The mean lung dose proved to be the easiest parameter to predict the reduction in PFTs 3-4 months following radiotherapy. For all patients the relation between the mean lung dose and the changes in PFTs could be described with one regression line through the origin and a slope of 1% reduction in PFT for each increase of 1 Gy in mean lung dose. Smoking and CMF chemotherapy influenced the reduction in PFTs significantly for VA and TL,COc, respectively. Patients treated with MOPP/ABV prior to radiotherapy had lower pre-radiotherapy PFTs than other patient groups, but did not show further deterioration after radiotherapy (at 3-4 months).

CONCLUSIONS

The relative reduction in VA, VC, FEV1 and TL,COc 3-4 months after radiotherapy for breast cancer and malignant lymphoma can be estimated before radiotherapy based on the mean lung dose of each individual patient and taking into account the use of chemotherapy and smoking habits of the patient.

Applicability of the single-breath carbon monoxide diffusing capacity in a Norwegian Community Study

The test of single-breath diffusing capacity for carbon monoxide (DLCO) has been widely used in population surveys. However, little is known about the effect of meeting or failing to meet the criteria for acceptability of this test. The American Thoracic Society (ATS) recommends a breathholding time of 9 to 11 s, two measurements within +/- 10% or 3 ml CO(STPD)/min/mm Hg of the average DLCO, and an inspiratory vital capacity (IVC) of at least 90% of the largest previously measured forced vital capacity (FVC) as criteria for this test. The objective of the present study was to examine the extent to which these criteria were met in a community study. To do this, a random sample of 3,740 persons, aged 15 to 70 yr, of the general population of the city of Bergen and 11 surrounding municipalities on the southwest coast of Norway were enrolled in a two-phase cross-sectional study. In the second phase, a stratified sample (n = 1,512) of the respondents to the postal questionnaire used for recruitment for the study (n = 3,370) were invited to a clinical and respiratory physiologic examination that included the DLCO test. The attendance rate was 84% (1,275 of 1,512). In the examination, all subjects were able to maintain a breathholding time of 9 to 11 s, and 98% had two DLCO values within +/- 10% or 3 ml CO(STPD)/min/mm Hg of the average DLCO. The criterion of an IVC of at least 90% of FVC in the two tests was met by 68% of the subjects. Younger age was an independent predictor of failure to meet the required criteria. Thus, only two-thirds of the participants fulfilled all of the ATS criteria for the DLCO test, the main reason for failure being an IVC of less than 90% FVC. This should not necessarily lead to the exclusion from further analysis of those failing to meet this criterion.

Olfactory thresholds for nicotine and menthol in smokers (abstinent and nonabstinent) and nonsmokers

Nonsmokers and smokers were compared for olfactory sensitivity to two odors associated with cigarettes: nicotine and menthol. Smokers were tested twice--while nonabstinent, and after 16-20 h of smoking abstinence. Smokers showed a higher olfactory threshold for nicotine than did nonsmokers, but the same threshold for menthol. Furthermore, when the smokers were abstinent, they showed a lower olfactory threshold for nicotine than when they were nonabstinent, but again, the same threshold for menthol. These results suggest a nicotine specific olfactory deficit in smokers that is reduced during abstinence.

Laboratory values and vital signs in male smokers and nonsmokers in phase I trials: a retrospective comparison

In a retrospective analysis of 13 phase I multiple-dose trials, clinical data from 100 volunteers who received placebo were investigated for differences in routine safety laboratory parameters and vital signs between smokers and nonsmokers. Of the 100 subjects, 47 were classified as smokers (cigarettes only) and 53 were classified as nonsmokers. Objectives of the analysis were to offer a basis for decision whether certain deviations of laboratory values or vital signs might be related to smoking rather than to a study drug or some external influence, and to explore whether smokers tend to present changes in laboratory values or vital signs during a trial that are different from changes that occur in nonsmokers. Regarding baseline values, which were defined as the mean of values at screening and the first day of the in-house stay, clinically and statistically significant differences between smokers and nonsmokers were found for total leukocytes and triglycerides (mean greater for smokers than nonsmokers), and total bilirubin (mean greater for nonsmokers than smokers). Comparison of changes during the study in smokers and nonsmokers showed a statistically and clinically significant difference only for triglyceride levels. Smokers had a slight decrease in triglyceride levels, whereas nonsmokers showed a marked increase in the respective values during the trials. Prospective studies with sufficiently large sample sizes are required to confirm the results of this retrospective analysis on a wider basis, and to possibly achieve significance for further differences between smokers and nonsmokers.

Early and late weight gain following smoking cessation in the Lung Health Study

The authors examine weight gains associated with smoking cessation in the Lung Health Study (1986-1994) over a 5-year follow-up period. A cohort of 5,887 male and female smokers in the United States and Canada, aged 35-60 years, were randomized to either smoking intervention or usual care. Among participants who achieved sustained quitting for 5 years, women gained a mean of 5.2 (standard error, 5.0) kg in year 1 and a mean of 3.4 (standard error, 5.5) kg in years 1-5. Men gained a mean of 4.9 (standard error, 4.9) kg in year 1 and a mean of 2.6 (standard error, 5.8) kg in years 1-5. In regression analyses, smoking-change variables were the most potent predictors of weight change. Participants going from smoking to quit-smoking in a given year had mean weight gains of 2.95 kg/year (3.61%) in men and 3.09 kg/year (4.69%) in women. Over 5 years, 33% of sustained quitters gained > or = 10 kg compared with 6% of continuing smokers. Also among sustained quitters, 7.6% of men and 19.1% of women gained > or = 20% of baseline weight; 60% of the gain occurred in year 1, although significant weight gains continued through year 5. The average gains and the high proportions of sustained and intermittent quitters who gained excessive weight suggest the need for more effective early interventions that address both smoking cessation and weight control.

A comparison of maximum oxygen consumption, aerobic performance, and endurance in young and active male smokers and nonsmokers

The purpose of this study was to compare 2.4-km running performance in 2,639 smoking (SM) and nonsmoking (NS) male conscripts aged 18 to 26 years. Maximum oxygen consumption (VO2max) and aerobic exercise endurance were also compared between SM and NS subjects (N = 156) stratified into various running performance bands. SM subjects ran significantly slower (10.59 +/- 1.17 minutes) than NS subjects (10.32 +/- 1.03 minutes) in the 2.4-km run test (p < 0.001). The mean VO2max of SM subjects (53.38 +/- 8.58 ml kg-1 min-1) was not significantly different from that of the NS subjects (54.42 +/- 7.82 ml kg-1 min-1) (p > 0.05). Exercise endurance time on the treadmill protocol (EXtm) was significantly longer in the NS group only among those who completed the 2.4-km run in < 9.01 minutes (p < 0.05). Maximum minute ventilation (VEmax) was also significantly higher in the NS group in the < 9.01-minute performance band. No other significant differences were found between SM and NS subjects in EXtm and VEmax. Mean maximum heart rate achieved during the tread-mill test ranged from 180 +/- 4 to 191 +/- 12 beats per minute in the SM group and from 183 +/- 5 to 188 +/- 19 beats per minute in the NS group. These were not significantly different (p > 0.05). In conclusion, smoking habit was shown to influence aerobic performance in the 2.4-km run, VEmax, and EXtm only during high-intensity aerobic exercise. VO2max was not influenced by smoking habit when aerobic performance was held constant.

Post-shift changes in pulmonary function in a cement factory in eastern Saudi Arabia

This cross-sectional study was conducted in 1992 in the oldest of three Portland cement producing factories in Eastern Saudi Arabia. The respirable dust level was in excess of the recommended ACGIH level in all sections. Spirometry was done for 149 cement workers and 348 controls, using a Vitalograph spirometer. FEV1, FVC, FEV1/FVC% and FEF25-75% were calculated and corrected to BTPS. A significantly higher post-shift reduction FEV1, FEV1/FVC% and FEF25-75% was observed in the exposed subjects. Multiple regression analysis showed a significant relationship between post-shift changes and exposure to cement dust but failed to support any relationship with smoking. These findings may indicate an increase in the bronchial muscle tone leading to some degree of bronchoconstriction as a result of an irritant effect induced by the acute exposure to cement dust.