Smoking-induced elevations in blood carboxyhaemoglobin levels. Effect on maximal oxygen uptake

A modelling approach to disentangle the factors limiting muscle oxygenation in smokers

Cigarette smoking is associated with a lower exercise capacity and lower muscle fatigue resistance. This is at least partly attributable to carboxyhaemoglobin (HbCO) in the blood that via reduction in the oxygen-carrying capacity, and the left-shift of the Hb-dissociation curve would reduce tissue oxygenation. On the other hand, a reduced oxygen uptake due to mitochondrial dysfunction would result in improved oxygenation. We used previously collected capillarisation, myoglobin and estimated cellular maximal muscle oxygen consumption data derived from succinate dehydrogenase-stained sections from the vastus lateralis muscle from six smokers and five non-smokers. These data were fed into an expanded Krogh tissue oxygenation model to assess whether an impaired muscle fatigue resistance in smokers is primarily due to HbCO or impaired mitochondrial respiration. The model showed that in smokers with 6% and 20% HbCO (causing a left-shift of the Hb-dissociation curve) average muscle oxygenation was reduced by 1.9% and 7.2%, respectively. Muscle oxygenation was increased by 13.3% when maximal mitochondrial respiration was reduced by 29%. A combination of a 29% reduction in maximal mitochondrial respiration and 20% HbCO led to no significant difference in muscle oxygenation from that in non-smokers. This indicates that while HbCO may explain the reduced exercise capacity after just one smoking session, in chronic smokers impaired mitochondrial respiration appears more important in reducing oxygen extraction and exercise capacity with only a small contribution of the left-shift of the Hb-dissociation curve.

Effects of High-Intensity Interval Training and Continuous Aerobic Training on Health-Fitness, Health Related Quality of Life, and Psychological Measures in College-Aged Smokers

The study examined the effects of exercise on health-fitness, health related quality of life (HRQOL), and psychological measures in college-aged smokers. Outcomes included HRQOL, hemodynamic, anthropometric, lung function, and cardiorespiratory endurance. Sixty physically inactive college-aged male smokers (18-30 years) were randomly assigned into three groups: high-intensity interval training (HIIT), continuous aerobic training (CAT), and a control (CON). Both HIIT and CAT groups completed 8 weeks of non-consecutive cycling sessions thrice weekly. The CON group were not subjected to the exercise intervention. Sixty participants met the inclusion criteria. Of these, 48 (HIIT: n = 18, CAT: n = 16, CON: n = 14) participants completed the study and were included in the final analysis. Compared to CON, HIIT significantly (p = 0.01) improved forced expiratory flow (FEF_75%) more than the CAT group (p = 0.29). HIIT provided a significant (p = 0.04) improvement in FEF_75% compared to CAT. Recovery heart rate (RHR) was significantly improved in participants assigned to HIIT (p = 0.00) and CAT (p = 0.002) groups compared with the CON. A significant difference in RHR was found in HIIT compared to CAT. The study findings indicate that both HIIT and CAT exercise interventions significantly improve markers of lung function and cardiorespiratory endurance, respectively. However, findings suggested that HIIT should be the preferred form of exercise regime among college-aged smokers for more significant, healthier benefits.

Cardiorespiratory Fitness Is Associated With Better Cardiometabolic Health and Lower PTSD Severity in Post-9/11 Veterans

INTRODUCTION

Post-traumatic stress disorder (PTSD) is associated with an increased risk of cardiovascular and metabolic diseases and physical inactivity. Cardiorespiratory fitness (CRF), which is modifiable by physical activity, is a strong independent predictor of cardiometabolic health. However, the relationship between CRF and cardiometabolic health in veterans with PTSD is unknown. Thus, this study aimed to explore the cross-sectional relationships among CRF, indices of cardiometabolic health (ie, HbA1c, blood lipids, blood pressure, waist-hip ratio, and body mass index), and PTSD severity in veterans with PTSD.

MATERIALS AND METHODS

This study was approved by the local Institutional Review Board. All participants were informed of the study risks and provided consent prior to participation. Participants (n = 13) completed a cardiopulmonary exercise test, a fasting blood draw, and the Clinician Administered PTSD Scale. Correlations between CRF and cardiometabolic health were examined with Spearman's rank correlations, and differences in PTSD symptom severity were explored as a function of CRF (ie, low-to-moderate vs. high CRF), using multiple linear regression.

RESULTS

Peak oxygen uptake ($\dot{\mathrm{V}}$O2peak) was correlated with high-density lipoproteins rho = 0.60, P = 0.04 and diastolic blood pressure rho = -0.56, P = 0.05. Ventilatory threshold was correlated with HbA1c rho = -0.61, P = 0.03 and diastolic blood pressure rho = -0.56, P = 0.05. Higher CRF was associated with lower total PTSD severity standardized β = -0.84, P = 0.01, adjusted R2 = 0.47, total Cluster C symptoms (avoidance/numbing) β = -0.71, P = 0.02, adjusted R2 = 0.49, and total Cluster D symptoms (hyperarousal) β = -0.89, P = 0.01, adjusted R2 = 0.41, while adjusting for age and smoking status.

CONCLUSIONS

These preliminary findings suggest that CRF and by proxy physical activity may be important factors in understanding the increased risk of cardiovascular and metabolic disease associated with PTSD.

Short-Term Cigarette Smoking in Rats Impairs Physical Capacity and Induces Cardiac Remodeling

Despite the strong evidence on the cardiac and renal damages after chronic exposure to cigarette smoke, there is a paucity of data on its short-term effects. The study evaluated the short-term effects of cigarette smoking on left ventricular (LV) remodeling, in vitro myocardial and renal function. Female Wistar rats were randomized to control (C) and cigarette smoking rats for eight weeks. Physical capacity was assessed using an adapted model of exhaustive swim; left ventricle (LV) morphology and function were also evaluated. Renal function was assessed by creatinine clearance and urine protein. The in vitro myocardial performance was analyzed in isolated papillary muscles. Rats exhibited reduced physical capacity after short-term cigarette smoking. Although there was no change on LV function, reduced chamber diameter was found in the smoking group associated with an increased LV wall thickness. There was augmented cardiac mass compared to C that was confirmed by increased cardiomyocyte nucleus volume, but in vitro myocardial performance and renal function were unchanged. A short-term cigarette smoking induces cardiac remodeling without abnormalities in function. The smoking group still preserved renal function and in vitro myocardial performance. However, the reduced physical capacity may suggest an impairment of the cardiac reserve.

Six years progression of exercise capacity in subjects with mild to moderate airflow obstruction, smoking and never smoking controls

BACKGROUND

Exercise capacity is an important feature in patients with COPD. Its impairment drives disability and dependency for daily activities performance. This study evaluated the six years change in exercise capacity in subjects with airflow obstruction and compared this to subjects without airflow obstruction, with and without a smoking history.

METHODS

Cardiopulmonary exercise tests (CPET) were repeatedly performed during a six years follow up period. Peak oxygen uptake (VO2peak), work rate (WRpeak), heart rate (HRpeak), minute ventilation (VEpeak), respiratory exchange ratio (RERpeak) and ventilatory reserve (VE/MVV) were collected as effort dependent outcomes. The slopes of oxygen uptake, ventilatory and mechanical efficiency (OUES, ΔVE/ΔVCO2 and ΔVO2/ΔWR) were collected as effort independent outcomes.

RESULTS

One hundred and thirty-eight subjects were included. Thirty-eight presented airflow obstruction (63±6 years, 74% men, FEV1 90±15%pred), 44 had a smoking history but no airflow obstruction (61±5 years, 61% men, FEV1 105±15%pred) and 56 had never smoked (61±7 years, 57% men, FEV1 117±18%pred). At baseline, the airflow obstruction group had slightly worse exercise capacity in comparison to the never smoking control group, in absolute terms and expressed as percentage of the predicted value (VO2peak = 27±5 versus 32±8 ml/min/kg, p<0.01; 112±29 versus 130±33%pred, p = 0.04). Most exercise variables showed a statistically significant yearly deterioration, with exception of VE/MVV, ΔVE/ΔVCO2 and ΔVO2/ΔWR. The yearly decline in VO2peak and OUES was not faster in subjects with airflow obstruction than in smoking and never smoking controls (VO2peak -67 (9) versus -76 (9) ml/min, p = 0.44 and versus -58 (9), p = 0.47; OUES -32 (11) versus -68 (10), p = 0.03 and versus -68 (13), p = 0.03).

CONCLUSIONS

With exception of VO2peak, effort dependent variables deteriorated faster in subjects with airflow obstruction compared to never smoking controls. The deterioration of effort independent variables, however, was not accelerated in the airflow obstruction group compared to controls.

Association of betel nut chewing with exercise performance in a military male cohort: the CHIEF study

INTRODUCTION

Betel nut chewing may cause obesity, neurohormonal activation and inflammation, possibly impairing exercise performances.

METHODS

We examined the cross-sectional association in 4388 military male adults aged 18-50 years from the cardiorespiratory fitness in armed forces study in Taiwan between 2013 and 2014. The status of betel nut chewing was classified as current and former/never based on each participant's response to a questionnaire. Physical fitness was evaluated by three basic exercise tests including 3000 m running, 2 min sit-ups and 2 min push-ups. Multiple logistic regression for the best 10% and the worst 10% performers in each exercise, and linear regression were used to determine the relationship.

RESULTS

There were 564 current chewers and 3824 non-current chewers for the analysis. The linear regression shows that current betel nut chewing was positively correlated with 3000 m running duration (r=0.37, p=0.042) after adjusting for age, service specialty, body mass index, exercise frequency and alcohol intake. In addition, the logistic regression shows that as compared with non-current chewers, current chewers had lower odds of being the top 10% performers in 2 min push-ups and higher odds of being the bottom 10% performers in 2 min sit-ups (ORs and 95% CIs: 0.71 (0.50 to 0.99) and 1.32 (1.00 to 1.75), respectively). However, the associations between betel nut chewing and physical fitness were all insignificant after further adjusting for current smoking.

CONCLUSIONS

Our findings suggest that the impairment of physical fitness associated with betel nut chewing of military young men might be mainly mediated or moderated by the coexisted cigarette smoking.

Relationship Between Exposure to Second-Hand Smoke in the Workplace and Occupational Injury in the Republic of Korea

Background

Most studies in the field of smoking exposure in the workplace linked to occupational safety have only focused on active smoking. Few studies have reported that exposure to second-hand smoke in the workplace is a possible factor increasing the risk of occupational injury without considering occupational characteristics. The aim of this study was to determine the association between occupational injury and level of exposure to second-hand smoke at the workplace among Korean workers, after taking into account occupational characteristics.

Method

Using data from the third Korean Working Conditions Survey, levels of exposure to second-hand smoke were categorized as none, moderate, and high. We investigated the influence of exposure to second-hand smoke on occupational injury using logistic regression analysis with stratification by sex, smoking status, smoke-free policy in the workplace, and occupational characteristics. Occupational characteristics (occupational classification, working schedule, length of working day, and co-exposure to occupational hazards in the workplace) were stratified and analyzed using logistic regression models to estimate the risk of occupational injury linked to exposure to second-hand smoke.

Results

Among all participants, there was a significant dose-dependent association between risk of occupational injury and level of exposure level to second-hand smoke. After stratification by sex and smoking status, there was a significant association between risk of occupational injury and exposure level to second-hand smoke. Moreover, there was a significant relationship between exposure to second-hand smoke in the workplace and occupational injury, depending on the smoking-free policy at workplace (odds ratio [OR] in completely non-smoking workplace, 4.23; OR in non-smoking workplace with separate smoking area, 2.98; OR in smoking workplace 2.84). Additionally, there was a significant relationship between risk of occupational injury and exposure to second-hand smoke after stratification by occupational classification, working schedule, long working hours, and co-exposure to hazards in the workplace.

Discussion

There was a dose-response relationship between occupational injury and exposure to second-hand smoke, even after stratification to reduce the impact of various potential confounders and after taking into account occupational characteristics. These findings provide greater insight into the effects of exposure to second-hand smoke on the working population and may direct further research and policy-making in this field.

Cardiovascular fitness in young males and risk of unprovoked venous thromboembolism in adulthood

BACKGROUND

Whether high cardiovascular fitness is associated with reduced risk of venous thromboembolism (VTE) is unknown. The present study aims to determine whether high cardiovascular fitness reduces the risk of VTE.

METHODS

A Swedish cohort of male conscripts (n = 773,925) born in 1954-1970 with no history of previous VTE were followed from enlistment (1972-1990) until 2010. Data on cardiovascular fitness using a cycle ergonometric test (maximal aerobic workload in Watt [W_max]) at conscription were linked with national hospital register data and the Multi-Generation Register. We identified all full-siblings and first-cousin pairs discordant for maximal aerobic workload. This co-relative design allows for adjustment for familial resemblance.

RESULTS

In total, 3005 (0.39%) males were affected by VTE. Cardiovascular fitness estimated with W_max was not associated with VTE risk when adjusted for body mass index (BMI). However, cardiovascular fitness estimated with W_max/kg and adjusted for BMI was associated with reduced risk for VTE (Hazard ratio (HR) 0.81, 95% confidence interval (CI) 0.78-0.85 per standard deviation compared with mean W_max/kg). The association was weaker over time and also when examining discordant first cousins and full-sibling pairs.

CONCLUSIONS

These results suggest that there is a relationship between cardiovascular fitness and weight that is important for future VTE risk. Key messages Whether high cardiovascular fitness is associated with reduced risk of venous thromboembolism (VTE) is unknown. A Swedish cohort of male conscripts (n = 773,925) tested with a cycle ergometric test with no history of previous VTE were followed from enlistment (1972-1990) until 2010. Cardiovascular fitness estimated with W_max/kg and adjusted for BMI was associated with reduced risk for VTE (HR 0.81, 95% CI 0.78-0.85). These results suggest that there is a relationship between cardiovascular fitness and weight that is important for future VTE risk.

Smoking and Early COPD as Independent Predictors of Body Composition, Exercise Capacity, and Health Status

The effects of tobacco smoke, mild/moderate COPD disease and their combined effect on health status (HS), body composition (BC), and exercise capacity (EC) impairment are still unclear. We hypothesized that smoking and early COPD have a joint negative influence on these outcomes. We evaluated 32 smokers (smoking history >10 pack/years), 32 mild/moderate COPD (current smokers or former smokers), and 32 never smokers. All individuals underwent medical and smoking status evaluations, pre and post-bronchodilator spirometry, BC [fat-free mass (FFM) and FFM index (FFMI)], EC [six-minute walk distance (6MWD)] and HS [Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36)]. FFM (p = 0.02) and FFMI (p = 0.008) were lower in COPD than never smokers. 6MWT, as a percentage of reference values for the Brazilian population, was lower in COPD and smokers than never smokers (p = 0.01). Smokers showed worse SF-36 score for functional capacity than never smokers (p<0.001). SF-36 score for physical functioning (p<0.001) and role-emotional (p<0.001) were impaired in COPD patients than smokers. SF-36 scores for physical functioning (p<0.001), role-physical (p = 0.01), bodily pain (p = 0.01), vitality (p = 0.04) and role-emotional (p<0.001) were lower in COPD than never smokers. Multiple linear regression analysis showed that both COPD diagnosis and smoking were inversely associated with FFMI, 6MWD and HS. Smoking and early COPD have a joint negative influence on body composition, exercise capacity and health status.

The effects of hemoglobin levels and their interactions with cigarette smoking on survival in nasopharyngeal carcinoma patients

There is very little published information regarding the prognostic value of hemoglobin (Hb) levels combined with smoking on the survival of patients with nasopharyngeal carcinoma (NPC), and the interactions between them remain unclear. A total of 2440 NPC patients were confirmed, and multivariate analysis was performed to identify valuable prognostic Hb levels in the entire population and in the cohort of smokers. The survival differences were compared using log‐rank tests. The multiplicative and additive interactions were assessed using Cox regression and a Microsoft Word Excel spreadsheet. Postradiotherapy (RT) Hb was an independent prognostic factor for overall survival (OS) (HR = 0.797; P = 0.006), failure‐free survival (FFS) (HR=0.811; P = 0.010), and loco‐regional failure‐free survival (LR‐FFS) (HR = 0.725; P = 0.000). In the cohort of smokers, pack‐years was also an independent predictor of OS (HR = 0.673; P < 0.001) and FFS (HR = 0.681; P < 0.001), LR‐FFS (HR = 0.663; P = 0.001). A significant positive additive effect was found for the interaction between low post‐RT Hb and high SI on OS, with RERI = 5.616, AP = 0.665, and S = 4.078. Stratified analyses demonstrated that heavy smokers with low post‐RT Hb had HRs of 2.295 (P < 0.001) for death, 2.222 (P < 0.001) for disease failure, and 2.267 (P < 0.001) loco‐regional recurrence compared with light smokers with high post‐RT Hb levels, and post‐RT Hb level is an important predictor of survival in patients with NPC. The positive interaction between post‐RT Hb level and pack‐years contributes to the elevated risk of poor survival. Oncologists should devote particular attention to heavy smokers with low post‐RT Hb levels in the future.

Effect of low-intensity continuous training on lung function and cardiorespiratory fitness in both cigarette and hookah smokers

BACKGROUND

The decline in cardiorespiratory fitness and lung function was higher in smokers. Training method could mitigate some of the negative consequences of smoking among smokers unable or unwilling to quit.

OBJECTIVE

To examine the effects of continuous training on lungs functional capability and cardiorespiratory fitness in smokers.

METHODS

Fifteen cigarette smokers, 14 hookah smokers, and 14 nonsmokers were assigned to low-intensity continuous training (20-30 minutes of running at 40% of maximum oxygen uptake (O2max)). Lung function and cardiorespiratory fitness parameters were determined using respectively spirometer and treadmill maximal exercise test.

RESULTS

Continuous training improved forced expiratory volume in one second (FEV1) and forced expiratory flow at 50% of FVC (FEF50 %) in all participants, smokers and nonsmokers (p < 0.05). In contrast, forced vital capacity (FVC) improvement was significant only among cigarette smokers (CS) (+1.7±2.21%, p < 0.01) and hookah smokers (HS) (+1.3±1.7 %, p < 0.05). Likewise, an improvement in cardiorespiratory fitness in both smokers groups without significant changes in diastolic blood pressure (DBP) for CS group and in velocity at maximum oxygen uptake (vO2max) for HS group.

CONCLUSION

The low-intensity continuous training improves cardiorespiratory fitness and reduces lung function decline in both cigarette and hookah smokers. It seems to be beneficial in the prevention programs of hypertension. It could have important implications in prevention and treatment programs in smokers unable or unwilling to quit.

Lung function profiles and aerobic capacity of adult cigarette and hookah smokers after 12 weeks intermittent training

INTRODUCTION

Pulmonary function is compromised in most smokers. Yet it is unknown whether exercise training improves pulmonary function and aerobic capacity in cigarette and hookah smokers and whether these smokers respond in a similar way as do non-smokers.

AIM

To evaluate the effects of an interval exercise training program on pulmonary function and aerobic capacity in cigarette and hookah smokers.

METHODS

Twelve cigarette smokers, 10 hookah smokers, and 11 non-smokers participated in our exercise program. All subjects performed 30 min of interval exercise (2 min of work followed by 1 min of rest) three times a week for 12 weeks at an intensity estimated at 70% of the subject's maximum aerobic capacity (VO2max). Pulmonary function was measured using spirometry, and maximum aerobic capacity was assessed by maximal exercise testing on a treadmill before the beginning and at the end of the exercise training program.

RESULTS

As expected, prior to the exercise intervention, the cigarette and hookah smokers had significantly lower pulmonary function than the non-smokers. The 12-week exercise training program did not significantly affect lung function as assessed by spirometry in the non-smoker group. However, it significantly increased both forced expiratory volume in 1 second and peak expiratory flow (PEF) in the cigarette smoker group, and PEF in the hookah smoker group. Our training program had its most notable impact on the cardiopulmonary system of smokers. In the non-smoker and cigarette smoker groups, the training program significantly improved VO2max (4.4 and 4.7%, respectively), v VO2max (6.7 and 5.6%, respectively), and the recovery index (7.9 and 10.5%, respectively).

CONCLUSIONS

After 12 weeks of interval training program, the increase of VO2max and the decrease of recovery index and resting heart rate in the smoking subjects indicated better exercise tolerance. Although the intermittent training program altered pulmonary function only partially, both aerobic capacity and life quality were improved. Intermittent training should be advised in the clinical setting for subjects with adverse health behaviors.

The exercise heart rate profile in master athletes compared to healthy controls

Endurance exercise protects the heart via effects on autonomic control of heart rate (HR); however, its effects on HR indices in healthy middle-aged men are unclear. This study compared HR profiles, including resting HR, increase in HR during exercise and HR recovery after exercise, in middle-aged athletes and controls. Fifty endurance-trained athletes and 50 controls (all male; mean age, 48·7 ± 5·8 years) performed an incremental symptom-limited exercise treadmill test. The electrocardiographic findings and HR profiles were evaluated. Maximal O2 uptake (52·6 ± 7·0 versus 34·8 ± 4·5 ml kg(-1)  min(-1) ; P<0·001) and the metabolic equivalent of task (15·4 ± 1·6 versus 12·2 ± 1·5; P<0·001) were significantly higher in athletes than in controls. Resting HR was significantly lower in athletes than in controls (62·8 ± 6·7 versus 74·0 ± 10·4 beats per minute (bpm), respectively; P<0·001). Athletes showed a greater increase in HR during exercise than controls (110·1 ± 11·0 versus 88·1 ± 15·4 bpm; P<0·001); however, there was no significant between-group difference in HR recovery at 1 min after cessation of exercise (22·9 ± 5·6 versus 21·3 ± 6·7 bpm; P = 0·20). Additionally, athletes showed a lower incidence of premature ventricular contractions (PVCs) during exercise (0·0% versus 24·0%; P<0·001). Healthy middle-aged men participating in regular endurance exercise showed more favourable exercise HR profiles and a lower incidence of PVCs during exercise than sedentary men. These results reflect the beneficial effect of endurance training on autonomic control of the heart.

The effects of cigarette smoking on aerobic and anaerobic capacity and heart rate variability among female university students

Aim

In this study, the effects of cigarette smoking on maximal aerobic capacity, anaerobic capacity, and heart rate variability among female university students were investigated.

Materials and methods

Twelve smokers and 21 nonsmokers participated in this study. All participants performed an intermittent sprint test (IST) and a 20 m shuttle run test to measure their anaerobic capacity and maximal aerobic capacity. The IST was comprised of 6 × 10-second sprints with a 60-second active recovery between each sprint. Heart rate variability was recorded while the participants were in a supine position 20 minutes before and 30 minutes after the IST.

Results

The total work, peak power, and heart rate of the smokers and nonsmokers did not differ significantly. However, the smokers’ average power declined significantly during sprints 4 to 6 (smokers versus nonsmokers, respectively: 95% confidence interval =6.2–7.2 joule/kg versus 6.8–7.6 joule/kg; P<0.05), and their fatigue index increased (smokers versus nonsmokers, respectively: 35.8% ± 2.3% versus 24.5% ± 1.76%; P<0.05) during the IST. The maximal oxygen uptake of nonsmokers was significantly higher than that of the smokers (P<0.05). The standard deviation of the normal to normal intervals and the root mean square successive difference did not differ significantly between nonsmokers and smokers. However, the nonsmokers exhibited a significantly higher normalized high frequency (HF), and significantly lower normalized low frequency (LF), LF/HF ratio, and natural logarithm of the LF/HF when compared with those of the smokers (P<0.05).

Conclusion

Smoking may increase female smokers’ exercise fatigue and decrease their average performance during an IST, while reducing their maximal aerobic capacity. Furthermore, smoking reduces parasympathetic nerve activity and activates sympathetic cardiac control.

Smoking is a poor prognostic factor for male nasopharyngeal carcinoma treated with radiotherapy

BACKGROUND AND PURPOSE

To evaluate the effect of smoking on prognosis of male nasopharyngeal carcinoma by comparing the treatment outcomes between smokers and non-smokers.

MATERIALS AND METHODS

A total of 2450 nasopharyngeal carcinoma patients were enrolled, including 1865 male patients. Matching was performed between smokers and non-smokers in male patients according to age, UICC clinical stage, T stage, N stage and treatment. Survival outcomes were compared using Kaplan-Meier analysis and Cox regression. Smoking index was calculated by multiplying cigarette packs per day and smoked time (year).

RESULTS

In male patients, smokers had significantly lower 5-year overall survival (70.1% vs. 77.5%, P<0.001) and locoregional recurrent free survival (76.8% vs.82.4%, P = 0.002) compared with non-smokers. Matched-pair analysis showed that smokers kept a high risk of death compared with non-smokers (HR = 2.316, P<0.001). High degree of smoking index (>15 pack-years) had a poor effect on overall survival (HR = 1.225, P = 0.016). When smoking index was more than 45 and 60 pack-years, the risk for death increased to 1.498 and 1.899 fold compared with non-smokers (P = 0.040, 0.001), respectively.

CONCLUSIONS

Smoking was a poor prognostic factor for male nasopharyngeal carcinoma. The heavier the patients smoked, the poorer prognosis they suffered.

Behavior and Knowledge of Iranian Professional Athletes towards Smoking

PURPOSE

This study aimed to assess the rate of tobacco consumption among professional athletes in Iran and assessing their knowledge and attitude in this regard.

METHODS

A total of 738 athletes from 10 different types of sports were evaluated. Athletes were all members of the priority leagues. After obtaining consent from the Physical Education Organization and coordination with the related federations, athletes were asked to fill out the standard questionnaire.

RESULTS

All understudy subjects were males. The mean age was 28.4±2.7 yrs. The mean age of initiation of sport in these subjects was reported to be 12.3±4.01 yrs. A total of 178 (24.6%) subjects had experienced cigarette smoking and 308 (42.3%) had experienced hookah smoking. Sixty four subjects (9%) were current smokers. The mean score of knowledge about hazards of smoking was 5.6±0.9 among those who had experienced smoking. This score was 7.9±0.5 among those with no smoking experience (P=0.04).

CONCLUSIONS

Rate of smoking among professional athletes is lower than general population average. So participation in organized sports may be a protective factor against tobacco use in people.

Smoking is associated with increased cartilage loss and persistence of bone marrow lesions over 2 years in community-based individuals

OBJECTIVE

To determine whether smoking is related to change in tibial and patella cartilage, and the development or persistence of bone marrow lesions (BMLs) over 2 years in a cohort of middle-aged adults.

METHODS

Two hundred and seventy-one adult subjects recruited from the Melbourne Collaborative Cohort Study underwent an MRI of their dominant knee at baseline and approximately 2 years later. Cartilage volume and BMLs were determined for both time points. At baseline, subjects also completed a questionnaire about current and past cigarette smoking.

RESULTS

Being a 'smoker' (former or current) was associated with increased annual loss of medial but not lateral or patella cartilage volume (medial: difference = 13.4 microl, P = 0.03; lateral difference = 4.86 microl, P = 0.45, patella difference = -2.57 microl, P = 0.79). A relationship between increasing pack-years smoked and increased medial cartilage volume loss was also observed (P = 0.04). Amongst people who had a BML at baseline, BMLs present in 'ever smokers' were 11.4 [95% confidence interval (CI) 1.54, 89.9; P = 0.02] times more likely to persist over 2 years than those present in 'never smokers'. In addition, the relationship between smoking and increased medial cartilage loss for subjects with a BML present at baseline was partially mediated by the persistence of the BMLs over 2 years.

CONCLUSION

This study contributes to the evidence of a detrimental effect of smoking on joint cartilage. Furthermore, it provides a possible mechanism that the association smoking shares with increased cartilage loss may be mediated via smoking impairing the ability for BMLs to resolve.

Blood haemoglobin concentrations are higher in smokers and heavy alcohol consumers than in non-smokers and abstainers: should we adjust the reference range?

The blood haemoglobin concentration is one of the most frequently used laboratory parameters in clinical practice. There is evidence that haemoglobin levels are influenced by tobacco smoking. The objective of this study was to evaluate the impact of smoking and alcohol consumption on haemoglobin concentrations in apparently healthy subjects living at sea level. A retrospective, epidemiological cohort study was performed in 1984. Participants were 1,503 men and 1,437 non-pregnant women evenly distributed in age cohorts of 30, 40, 50, and 60 years. Information of smoking habits and alcohol consumption were obtained by a questionnaire. Haemoglobin was measured in the fasting state on Coulter-S. Men displayed no difference in mean haemoglobin levels in the four age groups. In women, mean haemoglobin increased gradually with age (p = 0.001). Fifty-nine percent of men and 50% of women were daily smokers. Female smokers displayed a significant positive correlation between number of cigarettes/day and haemoglobin concentrations (r = 0.12, p = 0.002). Heavy smokers (more than ten cigarettes/day) had significantly higher mean haemoglobin (1.4% higher in men, on average 3.5% higher in women) than non-smokers (p < 0.01). Smokers demonstrated a significant correlation between cigarettes/day and drinks/week in men (r = 0.24, p < 0.001) and women (r = 0.16, p < 0.001). Non-smokers displayed a significant positive correlation between drinks/week and haemoglobin concentrations in men (r = 0.14, p = 0.001) and women (r = 0.08, p = 0.05). In non-smokers, alcohol consumption >14 drinks/week and more than seven drinks/week for men and women, respectively, increased mean haemoglobin by 1.3% in men and by average 1.9% in women compared with those consuming < or =14 and less than or equal to seven drinks/week. Smokers displayed similar results. Body mass index per se had no direct influence on haemoglobin levels but had indirect positive influence in men through its correlation with tobacco smoking and alcohol consumption. Tobacco smoking has an increasing effect on haemoglobin concentrations in both genders, which is proportional to the amount of tobacco smoked. The effect appears to be more pronounced in women. Likewise, high alcohol consumption has an increasing effect on haemoglobin in both genders, being most pronounced in women. However, in clinical biochemistry, the relatively small changes in haemoglobin do not justify the use of separate reference ranges in smokers and alcohol consumers.

Carbon monoxide inhalation reduces skeletal muscle fatigue resistance

AIM

To determine whether inhalation of carbon monoxide (CO), resulting in carboxyhaemoglobin (COHb) levels observed in smokers, had an effect on muscle fatigue during electrically evoked and voluntary muscle contractions.

METHODS

Young non-smoking males inspired CO from a Douglas bag until their COHb level reached 6%. During the control condition the same participants inspired ambient air from a Douglas bag for 6 min. Fatigue was assessed as the decline in torque in isometric knee extensions, during 2 min of electrically evoked contractions (30 Hz, 1 s on, 1 s off) and during 2 min of maximal isometric voluntary contractions (1 s on, 1 s off). A fatigue index (FI) was calculated as the ratio of final torque : initial torque. Time to peak torque (TPT) and half relaxation time ((1/2)RT) were also determined for the electrically evoked contractions.

RESULTS

The FI during both the voluntary fatigue test (control: 0.80 +/- 0.09 vs. CO: 0.70 +/- 0.08; mean +/- SD) and that of the fatigue test with electrically evoked contractions (control: 0.61 +/- 0.09 vs. CO: 0.53 +/- 0.12) was significantly lower after CO inhalation than after inhalation of ambient air (P < 0.05). There was, however, no effect of CO on the changes in TPT or (1/2)RT during the fatigue test.

CONCLUSION

Carbon monoxide inhalation resulting in COHb levels found in smokers has an acute impact on the ability of the muscle to resist fatigue.

Effects of chronic smoking on exercise tolerance and on heart rate-systolic blood pressure product in young healthy adults

BACKGROUND

Smoking is a major cause of cardiovascular disease and mortality. Smoking-related deaths in Greece account for 23%, whereas 41% of young Greeks are smokers, the highest percentage in Europe. The purpose of this study was to examine the effects of chronic smoking on the rate-pressure product and exercise tolerance in young, healthy male smokers.

DESIGN AND METHODS

Forty-two smokers and 51 nonsmokers were selected from a population of 543 students based on their age, sex, body mass index, physical fitness, smoking habit and health status. All participants were tested with the standard Bruce treadmill protocol. The rate-pressure product was obtained at rest and during exercise at a given submaximal workload. The evaluation of exercise tolerance was based on peak workload achieved and maximal exercise test duration.

RESULTS

The smokers had a higher rate-pressure product at rest (P<0.001) due to their higher resting heart rate (P<0.001). Resting values of blood pressure did not differ significantly between the two groups. During exercise, smokers had a greater rate-pressure product (P<0.001), mainly due to their significantly higher systolic blood pressure (P=0.008). The smokers had a higher submaximal heart rate (P=0.005), but the differences in heart rate between groups were reduced for smokers during exercise when compared to rest. The smokers' exercise tolerance was impaired and their maximal exercise test duration time was significantly shorter (P<0.001).

CONCLUSIONS

Chronic smoking was found to affect young male smokers' cardiovascular fitness, impairing the economy and decreasing the capacity of their circulatory system.

Efeitos cardiovasculares da abstinência do fumo no repouso e durante o exercício submáximo em mulheres jovens fumantes

OBJETIVO: O objetivo do presente estudo foi verificar o efeito da abstinência do fumo nas respostas cardiovasculares ao exercício físico progressivo submáximo em mulheres sedentárias fumantes. MÉTODOS: A pressão arterial sistólica (PAS) e diastólica (PAD) e a freqüência cardíaca (FC) foram medidas de forma não invasiva em mulheres jovens não fumantes (MNF, n = 7) e fumantes (MF, n = 7), sem e com abstinência do fumo por 24 horas, em repouso, durante a realização do teste submáximo em bicicleta ergométrica e na recuperação. RESULTADOS: Em repouso, a PAD e a FC foram maiores nas MF (76 ± 1mmHg e 86 ± 5bpm) quando comparadas com as MNF (68 ± 2mmHg e 72 ± 2bpm). Após 24 horas sem o tabaco essas medidas foram normalizadas. Durante o exercício, a PAS e a FC aumentaram nos grupos estudados. A PAD foi maior nas MF (~15%) em relação às MNF em todos os estágios do exercício. Na situação de abstinência, a PAD aumentou somente no último estágio de exercício. Na recuperação tanto a PAD quanto a FC foram maiores nas MF, na situação basal e com abstinência de 24h, quando comparadas as MNF. CONCLUSÃO: Estes resultados demonstram que mulheres jovens fumantes apresentam prejuízo em parâmetros hemodinâmicos em repouso e em resposta ao exercício submáximo, os quais, podem ser em parte revertidos pela abstinência em curto prazo do uso do tabaco.

Cigarette smoking and the risk for cartilage loss and knee pain in men with knee osteoarthritis

OBJECTIVE

To examine the effects of smoking on cartilage loss and pain at the knee in individuals with knee osteoarthritis.

METHODS

159 men with symptomatic knee osteoarthritis who participated in a 30-month, prospective, natural history study of knee osteoarthritis were examined. The more symptomatic knee was imaged using magnetic resonance imaging (MRI) at baseline, and again at 15 and 30 months of follow-up. Cartilage was scored using the Whole-Organ MRI Score semiquantitative method at the medial and lateral tibiofemoral joints and at the patellofemoral joint. At baseline and follow-up visits, the severity of knee pain was assessed using a Visual Analogue Scale pain score (0-100 mm).

RESULTS

Among the 159 men, 19 (12%) were current smokers at baseline. Current smokers were younger (mean (standard deviation (SD)) age 62 (9) v 69 (9) years) and leaner (mean (SD) body mass index (BMI): 28.9 (3.2) v 31.3 (4.8) kg/m(2)) than men who were not current smokers. When adjusted for age, BMI and baseline cartilage scores, men who were current smokers were found to have an increased risk for cartilage loss at the medial tibiofemoral joint (odds ratio (OR) 2.3, 95% confidence interval (CI) 1.0 to 5.4) and the patellofemoral joint (OR 2.5, 95% CI 1.1 to 5.7). Current smokers also had higher adjusted pain scores at baseline (60.5 v 45.0, p<0.05) and at follow-up (59.4 v 44.3, p<0.05) than men who were not current smokers.

CONCLUSIONS

Men with knee osteoarthritis who smoke sustain greater cartilage loss and have more severe knee pain than men who do not smoke.

Simulation of Correlated Continuous and Categorical Variables using a Single Multivariate Distribution

Clinical trial simulations make use of input/output models with covariate effects; the virtual patient population generated for the simulation should therefore display physiologically reasonable covariate distributions. Covariate distribution modeling is one method used to create sets of covariate values (vectors) that characterize individual virtual patients, which should be representative of real subjects participating in clinical trials. Covariates can be continuous (e.g., body weight, age) or categorical (e.g., sex, race). A modeling method commonly used for incorporating both continuous and categorical covariates, the Discrete method, requires the patient population to be divided into subgroups for each unique combination of categorical covariates, with separate multivariate functions for the continuous covariates in each subset. However, when there are multiple categorical covariates this approach can result in subgroups with very few representative patients, and thus, insufficient data to build a model that characterizes these patient groups. To resolve this limitation, an application of a statistical methodology (Continuous method) was conceived to enable sampling of complete covariate vectors, including both continuous and categorical covariates, from a single multivariate function. The Discrete and Continuous methods were compared using both simulated and real data with respect to their ability to generate virtual patient distributions that match a target population. The simulated data sets consisted of one categorical and two correlated continuous covariates. The proportion of patients in each subgroup, correlation between the continuous covariates, and ratio of the means of the continuous covariates in the subgroups were varied. During evaluation, both methods accurately generated the summary statistics and proper proportions of the target population. In general, the Continuous method performed as well as the Discrete method, except when the subgroups, defined by categorical value, had markedly different continuous covariate means, for which, in the authors' experience, there are few clinically relevant examples. The Continuous method allows analysis of the full population instead of multiple subgroups, reducing the number of analyses that must be performed, and thereby increasing efficiency. More importantly, analyzing a larger pool of data increases the precision of the covariance estimates of the covariates, thus improving the accuracy of the description of the covariate distribution in the simulated population.

Clinical factors associated with fatigue in haematologic cancer patients receiving stem-cell transplantation

We have evaluated risk factors associated with fatigue in 220 cancer patients during hospitalization for stem-cell transplantation (SCT). Fatigue was assessed using a validated one-item energy scale and a comprehensive set of fatigue predictors, at hospital admission (baseline), day of SCT, and 7 days and 14 days after SCT. In cross-sectional multivariate analysis, depression was the variable most consistently and strongly associated with fatigue; other factors significantly associated with fatigue at some time during the study included older age, higher education, smoking, lower Karnofsky performance status, loss of appetite, nausea/vomiting, pain, higher regimen-related toxicity, low hemoglobin level, requirement for red blood-cell transfusions, and third year of the study period. In prospective multivariate analysis, baseline depression showed significance or a trend towards significance in its ability to predict subsequent measures of fatigue during hospitalization. Our findings may help to shed light on the mechanisms underlying fatigue and may also guide future interventions.

Carbon monoxide specifically inhibits cytochrome c oxidase of human mitochondrial respiratory chain

Carbon monoxide (CO) toxicity is the result of a combination of tissue hypoxia and direct CO-mediated damage at a cellular level, since not all the signs and symptoms presented can be explained only by the formation of carboxyhaemoglobin. Mitochondria, specially the electron transport chain, seem to be the target for CO at a subcellular level. However, the direct effect of CO in individual complexes of the human mitochondrial respiratory chain has not been completely elucidated. We here studied the in vitro effect of CO on individual complexes of the mitochondrial respiratory chain of human mitochondria. We obtained muscle tissue from 10 healthy people who underwent orthopaedic surgery for hip replacement. Isolated mitochondria were incubated for 5 min. under CO concentrations of 50, 100 and 500 ppm. Afterwards, enzymatic activities of individual complexes of the mitochondrial respiratory chain were assessed in vitro and compared with those obtained in basal (synthetic air without CO) conditions. Cytochrome c oxidase (complex IV of the mitochondrial respiratory chain) activity showed a decrease from 836+/-439 nmol/min./mg of mitochondrial protein after air incubation to 670+/-401, 483+/-182, and 379+/-131 nmol/min./mg after 50, 100 and 500 ppm of CO incubation, respectively (20%, 42% and 55% decrease in cytochrome c oxidase activity). This gradual decrease in cytochrome c oxidase was found to be statistically significant (P<0.001). Other complex activities showed no any significant variation. Carbon monoxide is toxic for mitochondria in man, altering the mitochondrial respiratory chain at the cytochrome c oxidase level. This inhibition in cytochrome c oxidase may play a role in the development of the symptoms observed in acute CO poisoning, and in some diseases related to smoking.

The influence of simultaneous whole body exposure to cigarette smoke and low-protein diet feeding on fertility, reproduction, and progeny of rats

The aim of the present study was to evaluate the toxicological influence of different concentrations of tobacco smoke and low-protein diet on fertility, reproduction, and survival of offspring of Wistar female rats. We studied three generations, two litters in each. There were 192 animals in parent generation. Animals were exposed to three different concentrations of tobacco smoke that were reflected by the carbon monoxide (CO) concentration (500, 1000, and 1500 mg CO/m3 air) during 11 weeks (six before and two weeks during mating, and three weeks of pregnancy). Additionally, animals were divided into two subgroups that were fed normal or low-protein diet. In the present study, we concentrated on the indices describing the reproduction ability, fertility, and rearing of pups of mothers exposed to tobacco smoke. The parameters of newborns survival were estimated also. We concluded that neither tobacco smoke exposure nor the low-protein diet changed the duration of pregnancy. The tobacco smoke in all doses and low-protein diet had a negative influence on fertility, reproduction, and survival of newborns from exposed mothers. This influence was mainly attributed to the tobacco smoke exposure. The levels of carboxyhaemoglobin were increasing with increasing tobacco smoke concentration.