Age-associated changes in nicotine dependence.

OBJECTIVES: Nicotine is the primary factor responsible for tobacco dependence among individuals who smoke. Nicotinic receptors and nicotine-associated metabolism, two significant aspects of nicotine dependence, are influenced by age. To date, however, the relationship between age and nicotine dependence has not been investigated. STUDY DESIGN: Cross-sectional. METHODS: Data were obtained from the national smoking cessation programme for South Korea. Data obtained from current smokers in 2008 (n = 338,566) were used as baseline measures. Nicotine dependence was determined by the Fagerström Test for Nicotine Dependence (FTND). Cigarettes per day (CPD) and FTND were the dependent variables. As CPD is a major component of FTND, scores on the FTND minus scores related to CPD were also used as a dependent variable. The relationships between age and the dependent variables (FTND, CPD, partial FTND) were investigated. Quadratic regression models were used to test the non-linear relationship between age and nicotine dependence after adjusting for other covariates. RESULTS: Analyses relying on nicotine dependence (FTND and partial FTND scores) and CPD produced similar results in relation to age. Specifically, the values of all three dependent variables increased with age until approximately 50 years of age, at which point they decreased. Additionally, nicotine dependence and CPD were associated with age of smoking initiation, smoking duration, alcohol-related problems, body mass index and residential area. After adjusting for other nicotine-dependence-related factors, the linear and quadratic terms of age were statistically significant in the multiple regression models. CONCLUSIONS: In the present study, both nicotine dependence and CPD displayed an inverse U-shaped relationship with age, with a significant peak at 50 years of age. The results suggest that tobacco control policies should target issues related to nicotine dependence according to age group.

Using molecular markers to identify two major loci controlling carotenoid contents in maize grain.

Maize is an important source of pro-vitamin A; beta-carotene, alpha-carotene and beta-cryptoxanthin, and the non-pro-vitamin A carotenoids including lutein and zeaxanthin. In the present study, a recombinant inbred (RI) population with 233 RI lines derived from a cross between By804 and B73 was employed to detect QTL for these nutritionally important components in maize grain. High Performance Liquid Chromatography was used to measure amounts of individual carotenoids over 2 years. A genetic linkage map was constructed with 201 molecular markers. In all, 31 putative QTL including 23 for individual and 8 for total carotenoids were detected on chromosome(s) 1, 3, 5, 6, 7, 8 and 10. The notable aspect of this study was that much of the phenotypic variation in contents of carotenoids could be explained by two loci (y1 and y9), and the QTL for carotenoids elucidated the interrelationships among these compounds at the molecular level. A gene targeted marker (Y1ssr) in the candidate gene phytoene synthase 1 (psy1) tightly linked to a major QTL explaining 6.6-27.2% phenotypic variation for levels of carotenoids was identified, which may prove useful to expedite breeding for higher level of carotenoids in maize grain. This functionally characterized gene (psy1) could also be exploited for further development of functional marker for carotenoids in maize. The QTL cluster located at y9 locus may also be used for pyramiding favorable alleles controlling contents of carotenoids from diverse maize germplasm.

Cardiac dimensions, physical activity, and submaximal working capacity in youth of the Québec Family Study.

The relationships between cardiac dimensions and physical activity and submaximal working capacity were examined in 198 boys and 154 girls, aged 9-18 years, who were participants in the first phase of the Québec Family Study. The sample was divided into three age groups, 9-12 years, 13-15 years, and 16-18 years. Indicators of physical activity included estimated daily energy expenditure (EE) and time spent in moderate-to-vigorous physical activity (median metabolic equivalents of energy expenditure above resting metabolic rate >/=4.8). Submaximal physical working capacity (PWC(150)) was determined using a submaximal exercise test on a Monark cycle ergometer. Echocardiographically determined dimensions included posterior wall thickness, septal wall thickness, and left ventricular mass (LVM). The analyses were based on partial correlation and analysis of covariance, controlling for age and body surface area. Relationships between EE/physical activity variables and cardiac dimensions were low and, at best, moderate (r < 0.45). With subjects grouped into tertiles by indicators of physical activity, LVM was significantly different only among 16- to 18-year-old girls (157 g vs 134 g in the highest and lowest quartiles, respectively; P < 0.05). Correlations between cardiac dimensions and PWC(150) were also low (r < 0.30), with few significant relationships. In general, cardiac dimensions were not related to habitual physical activity and PWC(150) in young subjects aged 9-18 years. However, significant correlations were positive, as expected. LVM may be related to submaximal power output in boys since it accounts for 3% of the variance, after adjusting for age and BSA.

Physique, subcutaneous fat, adipose tissue distribution, and risk factors in the Québec Family Study.

OBJECTIVE: To investigate the relationships among subcutaneous fatness, subcutaneous adipose tissue (SAT) distribution, somatotype and risk factors for coronary heart disease (CHD). SUBJECTS: The sample included 1410 (715 male and 695 female) youths and adults from the Quebec Family Study. MEASUREMENTS: Six skinfolds and the dimensions necessary for the derivation of the Heath-Carter anthropometric somatotype (endomorphy, mesomorphy, ectomorphy) were measured. The six skinfolds were summed to provide an index of subcutaneous adiposity (SUM). In addition, the trunk-to-extremity skinfold ratio, adjusted for SUM using regression procedures (TER), and the first principal component (PC1) of skinfold residuals (also adjusted for SUM) were used to indicate SAT distribution, independent of the overall level of fatness. Risk factors for CHD included systolic and diastolic blood pressures, and fasting glycaemia, triglycerides (TGs), plasma cholesterol, high and low density lipoprotein (HDL-C and LDL-C) cholesterol, and the HDL-C/total cholesterol (CHOL) ratio. RESULTS: In general, SUM was positively correlated with endomorphy and mesomorphy, and negatively correlated with ectomorphy. On the other hand, SAT distribution was not associated with somatotype, except in females where TER and PC1 were negatively correlated with mesomorphy. Results of forward stepwise regression analyses to predict CHD risk factors, indicated that a significant proportion of the variance in the risk factors could be accounted for by SUM, SAT distribution and somatotype (up to 16%). SUM is the best predictor, entering the regressions first (most important) in six of 15 significant regressions in males and 14 of 16 significant regressions in females. Somatotype components enter as predictors 10 times in males, and six times in females. Similarly, TER and PC1 enter as predictors nine times in males and five times in females. CONCLUSIONS: Somatotype is related to SUM, while somatotype and SAT distribution are largely independent of one another. Furthermore, SUM, somatotype and SAT distribution are significant predictors of biological risk factors for CHD.

Television viewing, physical activity, and health-related fitness of youth in the Québec Family Study.

PURPOSE: To evaluate the relationships among television viewing time (TVTIME), physical activity, and health-related fitness in youth 9-18 years of age from the Québec Family Study. METHODS: The sample included 423 males and 361 females 9-18 years of age from the greater Québec city area. TVTIME, daily energy expenditure (EE), and moderate to vigorous physical activity (MVPA) were estimated. Four health-related fitness variables were tested: knee extension strength, physical work capacity at 150 beats x min(-1), situps, and sum of skinfolds. The body mass index (BMI) was also included. Relationships were assessed using correlations and analysis of covariance. RESULTS: Correlations between TVTIME and EE and MVPA were low and not significant, with no pattern by age group and gender. Those between TVTIME and fitness variables were also low and generally not significant, with no pattern by age and gender. Adolescents in the highest and lowest quartiles of TVTIME showed no consistent differences in EE, MVPA, and the four fitness items. Similarly, adolescents in the highest and lowest quartiles of EE, MVPA, and each fitness item did not consistently differ in TVTIME. CONCLUSIONS: The results indicate that time watching television has only a weak association with indicators of physical activity and health-related fitness in Québec youth. Since the data are from the early 1980s, generalizations to more current samples should be tempered with care.

Three mitochondrial DNA restriction polymorphisms in elite endurance athletes and sedentary controls.

This study examined the associations between elite endurance athlete (EEA) status and three mitochondrial DNA (mtDNA) restriction fragment length polymorphisms (RFLPs) in the subunit 5 of the NADH dehydrogenase (MTND5) locus and one in the D-loop region. A group of 125 Caucasian male EEA well endowed with the phenotypic expression of VO2max (78.9 +/- 3.8 mL x kg(-1) x min(-1), mean +/- SD) and 65 sedentary controls (SCON: VO2max = 39.8 +/- 8.2 mL x kg(-1) x min(-1)) participated in the study. VO2max was determined during an incremental exercise test on a cycle ergometer or a motor-driven treadmill. mtDNA was extracted from white blood cells or lymphoblastoid cell lines and specific regions were amplified by the polymerase chain reaction. The Pearson Chi-square statistic test and Fisher exact test revealed no significant association (P > 0.05) between any of the three mtDNA RFLPs and EEA status. The MTND5-BamHI RFLP at bp 13,470 (morph 3) was found in 12.8% of the EEA and 12.3% of the SCON (chi2 = 0.009, P = 0.92). The prevalence of the MTND5-Ncil RFLP at bp 13,364 (morph 2) was 12.9% and 14% for the EEA and SCON, respectively (chi2 = 0.043, P = 0.83). The D-loop-KpnI RFLP at bp 16,133 (morph 1) was found in 5.8% of the EEA and in 1.6% of the SCON (Fisher exact test = 1.80, P = 0.18). The MTND5-HincII RFLP at bp 12,406 (morph 1) was not present in this study sample. These results indicate no evidence for a difference in the frequency of two polymorphic restriction sites in the subunit 5 of the NADH dehydrogenase gene of mtDNA and one in the D-loop region between elite endurance athletes and sedentary controls.

Physical activity and health-related fitness in youth: a multivariate analysis.

PURPOSE: To evaluate the relationship between indicators of physical activity and health-related fitness in youth 9-18 yr. METHODS: A cross-sectional sample of 356 boys and 284 girls 9-18 yr of age from phase I of the Quebec Family Study was studied. The sample was divided into three age groups by gender, 9-12, 13-15, and 16-18 yr of age. Physical activity variables included two estimates of activity, estimated daily energy expenditure (EE) and estimated moderate-to-vigorous physical activity (MVPA), and one estimate of inactivity, time spent watching television per day (TVTIME). Health-related fitness variables were the sum of six skin folds (SUM), number of sit-ups in 1 min (SITUP), physical work capacity at 150 beats x min(-1) (PWC150), and static strength of the leg (LMS). Partial canonical correlation was used to quantify the relationship between standardized (z-transformed) activity variables and health-related fitness items, controlling for age. RESULTS: There is a weak to moderate association between physical activity and fitness in youth. The first activity canonical variate is a function of positive loadings for EE and MVPA, with a smaller, negative loading for TVTIME. The first fitness variate generally includes positive loadings for PWC150 and SITUP, with a small negative loading for the SUM and a small positive loading for LMS. The first canonical correlations indicate that the variance shared by the fitness and activity variates ranges from 11 to 21%. CONCLUSION: There is a significant relationship between activity and health-related physical fitness, but a large part of the variability (80-90%) in fitness is not accounted for by physical activity as measured in this study.

Physique and echocardiographic dimensions in children, adolescents and young adults.

Relationships between echocardiographic dimensions and the Heath-Carter anthropometric somatotype were considered in healthy, non-obese children (8-11 year olds, n = 143), adolescents (12 15 year olds, n = 216) and young adults (16-24 years, n = 190). Cardiac dimensions, measured by M-mode echocardiography at end-diastole, included left ventricular internal diameter (LVIDd), posterior wall thickness (PWTd), and interventricular posterior wall thickness (STd). Left ventricular mass (LVM) and left ventricular end-diastolic volume (LVEDV) were estimated. Partial correlations between cardiac dimensions and each somatotype component were calculated, controlling for age and the other two components. Only 9 out of 45 correlations in males and 7 of 45 correlations in females were significant (p < or = 0.05). LVM, LVEDV, and LVIDd were significantly related to somatotype in males, demonstrating significant positive correlations with mesomorphy (r = 0.25, 0.29 and 0.29, respectively) and ectomorphy (r = 0.22. 0.37, and 0.37, respectively), and LVEDV and LVIDd were related to endomorphy (r = 0.24 and 0.25, respectively) in 8-11 year old boys. In 8-11 year old females, endomorphy was related to STd (r = 0.41) and LVM (r = 0.34), while mesomorphy was related to PWTd (r = -0.34) and ectomorphy was related to PWTd (r = -0.36). In 12-15 year old females, mesomorphy was related to STd (r = 0.26) and in 16-24 year old females, endomorphy was related to LVIDd (r = 0.29) and LVEDV (r = 0.32). Overall, the correlations between somatotype and cardiac dimensions were low, ranging from -0.36 to +0.41, with no clear pattern in either sex. Additionally, a backward stepwise regression analysis indicated that body size was more important in predicting echocardiographic dimensions than somatotype. Thus, physique, as estimated with the Heath-Carter anthropometric somatotype, is not related to echocardiographic dimensions in children, youths and young adults.

Muscle-specific creatine kinase gene polymorphisms in elite endurance athletes and sedentary controls.

The purpose of this study was to investigate the association between elite endurance athlete (EEA) status and two restriction fragment length polymorphisms (RFLPs) at the muscle-specific creatine kinase (CKMM) gene locus. Genomic DNA was extracted from white blood cells or lymphoblastoid cell lines of 124 unrelated Caucasian male EEA (VO2max > 73 mL.kg-1.min-1) and 115 unrelated Caucasian sedentary male controls (SCON). The genetic polymorphism at the CKMM locus was detected by the polymerase chain reaction and DNA digestion with the NcoI and TaqI restriction endonucleases. The allelic frequencies for the NcoI and TaqI RFLPs were not different (P > 0.05) between EEA and SCON subjects. The three expected genotypes for CKMM-NcoI (1170/1170 bp, 1170/985 + 185 bp, and 985 + 185/985 + 185 bp) and CKMM-TaqI (1170/1170 bp, 1170/1020 + 150 bp, and 1020 + 50/1020 + 150 bp) were observed in the EEA and SCON groups. These genotype frequencies were in Hardy-Weinberg equilibrium, but they were not significantly (P > 0.05) different between the EEA and SCON. A strong (P < 0.001) linkage disequilibrium was detected among the NcoI and TaqI RFLPs in both EEA and SCON. These findings indicate that the skeletal muscle CK-NcoI and CK-TaqI gene polymorphisms are not associated with the elite endurance athlete status.

Changes in plasma electrolytes and muscle substrates during short-term maximal exercise in humans.

This study compared the effects of 3 short-term maximal exercise tests lasting 10, 30, and 90 sec upon blood volume, plasma electrolytes, glucose, glycerol, lactate and skeletal muscle ATP, PC, glycogen, and lactate concentrations. Seven sedentary male subjects were recruited and 5 of them were randomly assigned to each of the 3 protocols. The tests were performed on a modified ergocycle at workloads of 0.9, 0.075, and 0.05 kp.kg-1 body mass, respectively. Muscle biopsies were taken from the vastus lateralis before and immediately after each exercise. Venous blood samples were collected before, immediately after, and during the recovery (5, 20, 60, and 120 min). Plasma volume decreased during the 30- and 90-sec tests and was increased in all tests after 60 min of recovery. Plasma K+ increased during all tests and returned to normal values 5 min postexercise, except after the 90-sec test where it fell below resting values. Plasma Na+ and Cl- were unaffected. Blood lactate increased in all tests, glucose increased after the 90-sec test, and glycerol increased after the 30- and 90-sec tests. All 3 tests brought relatively similar changes in muscle ATP, PC, and glycogen while muscle lactate changes were related to exercise duration. These results suggest that a normal hydration status is important for a subject undergoing short training bouts, and that high-intensity tests of short duration do not require a special nutritional regimen to enhance glycogen reserves.

Twin resemblance in somatotype and comparisons with other twin studies.

Twin resemblance in somatotype components was considered in 28 male and 34 female monozygotic (MZ) twin pairs and 19 male and 21 female dizygotic (DZ) twin pairs, 9.3-23.5 years of age. The Heath-Carter anthropometric somatotype method was used. Mean somatotypes of male twins and female twins did not differ, whereas male twins were significantly more mesomorphic than female twins. Twin resemblance was evaluated in two ways: first, treating each somatotype component independently of the other two (as in earlier twin studies), and, second, looking at resemblance in each somatotype component after statistically controlling for the other two components (thus treating the somatotype as a composite). Intraclass correlations were consistently higher in MZ than in DZ twins of both sexes, and within-pair variances were consistently lower in MZ than in DZ twins of both sexes. However, after controlling for the effects of the other two somatotype components, within-pair variances of male MZ and DZ twins for each somatotype component did not differ. In general, Heath-Carter anthropometric somatotype components show (1) significant resemblance in MZ and DZ twins within each sex, although the degree of resemblance is altered in male twins when a different analytic strategy is used, (2) no sex difference in degree of resemblance, and (3) greater resemblance within MZ twin pairs than within DZ twin pairs. These results are compatible with the presence of genetic variation affecting physique in adolescents and young adults.

Effect of anaerobic exercise on serum enzymes of young athletes.

The purpose of the study was to investigate the effect of anaerobic exercise on serum enzymes lactate dehydrogenase (LDH), creatine phosphokinase (CPK), and aspartate aminotransferase (AST) on elite junior male (n = 5) and female (n = 5) alpine skiers who ranged in age from 12 to 15 years. An intensive treadmill run to exhaustion (10.5 km.hr-1, 20% grade) was performed. Blood samples were drawn from the antecubital vein before and 5 min after the exercise. None of the enzyme activities had changed after exercise, and the performance time of treadmill run (male: 53.0 sec and female: 52.6 sec) was similar between groups but the serum CPK activities of the boys were consistently higher than those of the girls and the differences were significant (p less than 0.05).

Physical fitness of militia forces.

Anthropometry and physical fitness of Canadian militia infantry (n = 19) and militia service battalion (SVC, n = 27) men, ranging in age from 17 to 21 years, were examined and were compared with recent Canadian fitness norms. The height of the infantry was taller (p less than 0.05) than that of civilians. There was no difference between the two groups for the body mass index (BMI), skinfolds, grip strength, and maximum oxygen consumption rate. Flexibility and muscular endurance (sit-ups) of the infantry were greater (p less than 0.01) than those of the militia service battalion. Skinfolds and muscular endurance of the militia were above the average, and BMI and maximum oxygen consumption rate of the militia were below the average for civilians. Further study is needed to establish the fitness criteria that should be met by the militia in the future.

A physiological profile of elite Canadian freestyle wrestlers.

There has been an improvement in Canadian freestyle wrestling performance over the past five years. Medals are now being won at World and Olympic competitions. The present investigation provides baseline physiological data which have been used in the prescription of individual training programs for these athletes. This information is also available to the coaches and contributes to the strategy for individual matches. Generally, the Canadian wrestlers have a physiological profile similar to elite wrestlers from other countries. Maximal aerobic power is comparable to or greater than previously reported values. Needle biopsies reveal exceptionally large fast twitch fibre areas in vastus lateralis. However, anaerobic capacity and upper body strength are less than values reported for other elite athletes.