"Withdrawal symptoms" in adolescents: a comparison of former smokers and never-smokers.

Since the early 1980s, investigators have been reporting that adolescent smokers felt "dependent" on cigarettes and that adolescents trying to quit smoking experienced the same withdrawal symptoms observed in adult quitters, including restlessness, insomnia, increased appetite and weight gain, irritability or anger, depression, craving for cigarettes, and trouble concentrating. We hypothesized that most of these symptoms might be attributed to adolescence itself. To investigate this hypothesis, we examined the prevalence of these seven "adult" withdrawal symptoms in a population of adolescent former smokers and never-smokers. Participants were high school students in Houston, Texas, participating in a nested, group-randomized control group study designed to estimate the impact of a CD-ROM intervention for smoking prevention and cessation. We measured differences in symptoms frequency between never-smokers and former smokers, matched in a 2:1 ratio on sex and race/ethnicity, and differences in symptoms among former smokers as a function of time since final quit attempt and prior level of smoking. Only former heavy smokers have shown significantly higher prevalence of withdrawal symptoms compared with never-smokers. Of the seven symptoms assessed, only craving incrementally increased with the intensity of smoking. Overall the individual withdrawal symptoms did not effectively differentiate between 112 never-smokers and 34 former lighter smokers (persons who used to smoke less than "a few cigarettes on most days"). Withdrawal symptoms can reliably differentiate former heavy smokers from light smokers and never-smokers, among adolescents. Because most adolescents tend to be lighter smokers, future tobacco use and cessation studies should interpret adult withdrawal symptoms among adolescents with caution.     

Responsiveness of homocysteine concentrations to food and supplemental folate intakes in smokers and never-smokers enrolled in a diet intervention trial.

We investigated circulating homocysteine concentrations in relation to smoking, folate intake (from food and supplements), serum folate concentrations, and other dietary variables. The present study is part of a parent trial assessing the effects of increasing vegetable, fruit, and fiber intakes and reducing the percentage of energy obtained from fat on breast cancer recurrence in 3,088 women previously diagnosed with breast cancer. Of the 121 smokers enrolled in the parent trial, 85 were available at baseline for the present study and were randomly matched to 85 never-smokers on baseline folate intake, age, and intervention status. Follow-up data were available on 53 smokers (22 intervention and 31 comparison) and 56 never-smokers (24 intervention and 32 comparison). No significant differences in circulating homocysteine and folate concentrations were observed between smokers and never-smokers at baseline. For smokers, significant decreases in circulating homocysteine and significant increases in folate concentrations (p < .05) from baseline to 12 months were observed in the comparison group. For never-smokers, significant decreases in circulating homocysteine and significant increases in folate concentrations were observed in the intervention and comparison groups (p < .05). In the multivariate analysis, changes in serum folate concentration and supplemental folic acid were significantly associated with change in plasma homocysteine concentrations (p < .05). These findings show that increasing supplemental folic acid can reduce homocysteine concentrations, which may have implications for lowering cardiovascular disease risk for smokers and never-smokers.     

Nanotech: propensity in foods and bioactives

Nanotechnology is seeing higher propensity in various industries, including food and bioactives. New nanomaterials are constantly being developed from both natural biodegradable polymers of plant and animal origins such as polysaccharides and derivatives, peptides and proteins, lipids and fats, and biocompatible synthetic biopolyester polymers such as polylactic acid (PLA), polyhydroxyalkonoates (PHA), and polycaprolactone (PCL). Applications in food industries include molecular synthesis of new functional food compounds, innovative food packaging, food safety, and security monitoring. The relevance of bioactives includes targeted delivery systems with improved bioavailability using nanostructure vehicles such as association colloids, lipid based nanoencapsulator, nanoemulsions, biopolymeric nanoparticles, nanolaminates, and nanofibers. The extensive use of nanotechnology has led to the need for parallel safety assessment and regulations to protect public health and adverse effects to the environment. This review covers the use of biopolymers in the production of nanomaterials and the propensity of nanotechnology in food and bioactives. The exposure routes of nanoparticles, safety challenges, and measures undertaken to ensure optimal benefits that outweigh detriments are also discussed.     

Influences affecting adolescent smoking behavior in China.

This study examined multiple influences on the use of tobacco by adolescents in China. Using the theory of triadic influences as a guide, we selected interpersonal, attitudinal/cultural, and intrapersonal constructs from baseline data to predict adolescent smoking 1 year later. We used prospective data from middle and high school students (N = 11,583) and their parents from the China Seven Cities Study, a longitudinal study that is evaluating the effects of changing economic and social factors on health behaviors including tobacco use. A multilevel regression analysis provided some support that each of the influences in the theory of triadic influences affects adolescent smoking in China. After adjusting for important confounders including age, gender, socioeconomic status, and smoking behaviors (lifetime and past 30-day) at baseline, we found significant risk factors within each of the three categories, including interpersonal influences (parental monitoring, good friend smoking, and peer smoking), attitudinal/cultural influences (school academic ranking, initial liking of smoking, and the meaning of smoking), and intrapersonal influences (susceptibility to smoking, and low self-confidence to quit smoking). Results suggest that the etiology of smoking among adolescents in China might be similar to that observed in western countries and that some of the techniques used successfully in prevention programs in those countries might be useful guides when developing prevention programs in China.     

Identifying and predicting adolescent smokers' developmental trajectories.

Very few studies have defined trajectories of smoking. In the present study, we modeled growth in adolescent smoking and empirically identified prototypical trajectories. We conceptualized escalation of smoking as a growth process and modeled rates of change and heterogeneity of these patterns using latent growth mixture modeling. The analysis identified six trajectories with low ambiguity about group membership (early rapid escalators, late rapid escalators, late moderate escalators, late slow escalators-smokers, stable puffers, and late slow escalators-puffers). A trajectory of quitters was not identified. We also examined predictors of the smoking trajectories. The predictors were assessed across the adolescent years and included variables related to smoking and other substance use, as well as a range of variables related to sociodemographic factors and mental health. Observed change in the pattern of predictors across age has implications for the mechanism of effect of these variables in relation to smoking trajectories, including predictors that differentiated among daily smokers, variables that may determine the trajectory (e.g., friends smoking), and variables that may result from the trajectory (e.g., marijuana use, less attachment to friends).     

Differences in smoking duration between Latinos and Anglos.

A smoker's risk of disease and death from cigarettes is related directly to the duration of smoking. The present study compared duration of smoking between a state-level population of Anglo versus highly acculturated Latino ever-smokers (N = 6,100). Kapla-Meier analysis was used to obtain weighted median smoking duration. Weighted Cox proportional hazard models were used to evaluate the relative likelihood of continued smoking, adjusted for demographics, smoking history, home and workplace smoking restrictions, and socioeconomic covariates (education, health insurance status, and poverty level). On average, Latinos continued smoking longer than Anglos (M = 30 years vs. 27 years; weighted Cox HR = 0.73; 95% CI = 0.60-0.89). The disparity remained significant when adjusted for demographic, smoking history, and smoking-rule covariates but was not significant when adjusted for socioeconomic status (HR = 0.89, 95% CI = 0.73-1.09). Education alone accounted for the majority of the disparity, more so than poverty or health insurance status. We conclude that highly acculturated Latino smokers may be at greater risk of cigarette disease and death related to longer duration of smoking associated with lower socioeconomic status.     

Overcoming barriers to recruitment and retention in adolescent smoking cessation.

Participant recruitment and retention have been identified as challenging aspects of adolescent smoking cessation interventions. Problems associated with low recruitment and retention include identifying smokers, obtaining active parental consent, protecting participants' privacy, respecting participants' autonomy, and making participation relevant and accessible to adolescents. This paper describes nine strategies for minimizing these recruitment and retention problems via a proactive telephone counseling intervention, and reports on their simultaneous implementation among 1,058 smokers from 25 high schools in Washington state. Results are as follows: (a) 85.9% of parents of minor-age seniors provided active consent for their teen's participation, (b) 89.8% of eligible smokers were successfully contacted by counselors, (c) 86.5% of contacted smokers consented to participate in the cessation counseling, (d) 93.8% of consented smokers participated in smoking cessation counseling calls, and (e) 72.2% of participating smokers completed their full intervention. These results demonstrate that older teens who smoke, and their parents, are receptive to confidential cessation counseling that is personally tailored, supportive of their autonomy, and proactively delivered via the telephone.     

Associations between parental smoking restrictions and adolescent smoking.

The purpose of this study was to examine the cross-sectional relation between reported levels of parental smoking restriction and several behavioral and cognitive variables in a sample of 757 (363 males, 394 females) adolescent smokers. Experimenters administered surveys to students in the homerooms of three Florida high schools. After controlling for student age, gender, and parental smoking status, results revealed that more restrictive parental smoking policies were significantly associated with less smoking on weekdays and weekend days, greater latency to smoking the first cigarette of the day, greater motivation to quit smoking, greater confidence in ability to quit smoking, and higher estimated risk perception regarding the health consequences of smoking. Results also revealed that 44% of adolescent smokers reported that their parents or legal guardians did not know that they smoked tobacco. These findings suggest that parental smoking restrictions may have the potential to impede adolescent progression to adult smoking behavior by reducing smoking rates and nicotine dependence, and increasing motivation to quit, self-confidence to quit, and health risk perception. Parental restrictions on smoking may present obstacles and inconveniences to adolescent smoking behavior that make smoking cessation a more attractive option.     

Water migration mechanisms in amorphous powder material and related agglomeration propensity

The agglomeration phenomenon of amorphous particulate material is a major problem in the food industry. Currently, the glass transition temperature (T_g) is used as a fundamental parameter to describe and control agglomeration. Models are available that describe the kinetics of the agglomeration process as a function of the distance of the material from T_g (i.e. T − T_g). In practice these models are often not applied because they assume that the powder material is instantly in equilibrium with the humidity conditions of the environment and that solid mobility only occurs at T > T_g. Insights in the kinetics and mechanisms of water transport in powder material can help to better understand and control powder agglomeration. For this purpose, gravimetric step-change water sorption experiments were performed on maltodextrins as a function of the water activity a_w. The maltodextrins vary in dextrose equivalents (DE), particle size and morphology. The experimental results were compared with a Fickian diffusion model in order to understand the dependency of the transport mechanism on water concentration gradient and material relaxation. The water transport kinetics in the maltodextrins with low DE (i.e. 6) were well described by Fickian diffusion for low a_w, independently of particle size and morphology, until relaxation phenomena started to occur at an a_w corresponding to T − T_g = −20 °C. The importance of the matrix relaxation phenomena on the water transport mechanism increased with increasing DE (i.e. 29 and 32), not showing any relationship with the T_g. The results of this study indicate that the water migration mechanism is controlled by relaxation phenomena when the amorphous material is still far from the glass–rubber transition. The T − T_g at which the relaxation phenomena occur depends on the material. On the contrary, the T − T_g parameter could well describe the onset of agglomeration, independently from the material properties. Therefore, it can be concluded that within the conditions of this study, matrix relaxation occurring far below T_g did not affect the onset of agglomeration.     

Development and validation of an adolescent smoking consequences questionnaire.

Several researchers have investigated the role of outcome expectancies in the initiation and maintenance of smoking behavior. Empirical studies with adults, using a validated self-report instrument, have shown that smokers identify higher levels of positive smoking expectancies and lower levels of negative smoking expectancies compared with nonsmokers and ex-smokers. Studies examining smoking outcome expectancies among adolescents have yielded similar findings, but many of these studies did not use a self-report expectancy measure validated with teens. Therefore, the present study sought to modify a well-known adult smoking expectancy instrument, the Smoking Consequences Questionnaire (SCQ), and to validate its factor structure with a community sample of adolescent nonsmokers and current smokers (aged 11-19 years). Results of a confirmatory factor analysis provided support for a seven-latent-factor structure modeled after the SCQ-Adult. As expected, smoking behavior and the intent to smoke in the future were associated with the endorsement of positive and negative smoking outcome expectancies. The psychometric data provide early support for the validity and reliability of this modified SCQ, renamed the Adolescent Smoking Consequences Questionnaire, for the assessment of smoking expectancies among smoking inexperienced and experienced teens.     

Cotinine levels in relation to smoking behavior and addiction in young adolescent smokers.

The goal of this study was to identify associations among self-reported nicotine exposure, nicotine addiction, and actual nicotine intake as measured by salivary cotinine levels in adolescent smokers. A total of 170 adolescent smokers with a mean age of 15 years were recruited from seven northern Californian public high schools. Data were collected on smoking behaviors, addiction, craving, and withdrawal. Nicotine dependence was assessed using a modified teen Fagerstr?m Tolerance Questionnaire (mtFTQ), a modified Nicotine Dependence Syndrome Scale (mNDSS), and a simple self-rating. Withdrawal was assessed using the Minnesota Withdrawal Questionnaire, and craving was assessed using a survey created by the authors. Salivary cotinine levels were collected from and analysed in participants who self-identified as smokers; data from the 54 participants who smoked in the past 4 days and whose salivary cotinine levels were greater than 0.1 ng/ml were used in the analysis. Among this group of adolescent smokers, the mean number of cigarettes smoked per day was 3.51 (SD = 3.44) and the mean level of salivary cotinine was 44.1 ng/ml (Mdn = 24.2). Even at this low level of nicotine exposure, cotinine was highly correlated with measures of nicotine dependence such as the mtFTQ (r = 0.497, p = .001), NDSS (r = 0.439, p = .002), timing of craving in the morning (r = -0.601, p = .000), and self-rated addiction (r = 0.562, p = .000). Most interesting, cotinine levels reached a plateau at around 4-5 cigarettes/day.     

Effect of Lactobacillus helveticus and Propionibacterium freudenrichii ssp. shermanii combinations on propensity for split defect in Swiss cheese

One of the least controlled defects in Swiss cheese is development of splits that appear during refrigerated storage after cheese is removed from the warm room. Such fissures, or cracks, in the body of the cheese can be as short as 1 cm, or long enough to span a 90-kg block. A 2 x 2 x 2 factorial experiment was used to determine the effect of different Lactobacillus helveticus/Propionibacterium freudenreichii ssp. shermanii starter culture combinations on the occurrence of split defect in Swiss cheese. Eights vats of cheese were made in summer and eight in winter. Each 90-kg block of cheese was cut into twenty-four 4-kg blocks and graded based on the presence of splits. Only small variations were found in the composition of cheeses made during the same season. There were no correlations between moisture, pH, fat, protein, calcium, lactose contents, D/L lactate ratio, or protein degradation that could be used to predict splits after 90 d of storage. However, cheese made in the summer had 2% higher moisture content and a greater prevalence of splits. There was a sixfold increase in amount of downgraded cheese between the best and worst culture combinations used during cheese manufacture. After 90-d storage, 14 to 90% of cheese had splits in the summer, and 1 to 6% in the winter. Split formation increased with time from 60 to 120 d of storage and extent of split formation was influenced by both the lactobacilli and propionibacteria cultures used.     

Reactivity to in vivo smoking cues in older adolescent cigarette smokers.

Most smokers initiate smoking in adolescence, and craving for cigarettes may play an important role in maintenance of smoking behavior and relapse to smoking during a quit attempt. Although a significant body of literature explores cue-reactivity in adult smokers, little has been published on cue-reactivity among adolescent smokers. In a previously published work, we found that videotaped smoking cues may not be robust in eliciting craving among adolescent smokers. Hence, in this preliminary study, we examined reactivity to in vivo smoking cues among adolescent smokers (N = 11, average age = 18.1 years, range = 15-19 years, predominantly female). Participants were presented with in vivo smoking and neutral cues (counterbalanced). We recorded subjective craving and real-time heart rate in response to each type of cue. Adolescent smokers had a significantly greater "desire" to smoke (p < .05) in response to smoking cues vs. both baseline and neutral cues. Participants had faster heart rates after the smoking cues during the epochs of 21-30 s and 31-40 s (p values<.05) as compared with baseline, and mean heart rate was higher during the smoking cues relative to neutral cues among participants who received the smoking cues first (p < .05). Results of this preliminary study further demonstrate the feasibility of conducting cue-reactivity studies with adolescent cigarette smokers. Findings from this study suggest that adolescent smokers may show patterns of responding to smoking cues similar to those of adult smokers. Implications for future laboratory studies with adolescent smokers are discussed.     

Sociometric status as a predictor of onset and progression in adolescent cigarette smoking.

The relation between sociometric status and adolescent cigarette smoking was examined in a 1-year longitudinal study. Students in 6th, 7th, and 8th grades (N=1,630) were asked to nominate peers in their grade at school whom they liked and peers whom they disliked. These nominations were used to classify participants into one of five sociometric categories (popular, rejected, controversial, neglected, and average). Participants also reported their lifetime cigarette use at two measurements in consecutive school years. The results indicated that rejected and controversial adolescents were more likely than average adolescents to (a) report lifetime smoking at time 1 (T1) and (b) report onset of smoking at time 2 (T2). However, among adolescents who had already tried cigarettes at T1, rejected and controversial youth were not at increased risk for progression in total lifetime cigarette smoking (i.e., higher levels of total lifetime cigarette use at T2). Thus the results confirm that controversial youth are similar to rejected youth in their risk for onset of cigarette smoking during adolescence.     

顶空固相微萃取-气相色谱-质谱/嗅闻仪结合电子鼻和多元统计方法对4种柠檬的风味差异分析

该研究旨在利用多种技术手段以及多元统计方法分析不同品种柠檬风味差异。采用气相色谱-质谱/嗅闻联用（Gas Chromatography-Mass Spectrometry/Olfactory,GC-MS/O）与电子鼻技术对不同品种柠檬中挥发性风味成分进行研究,并以主成分综合评价函数计算不同品种柠檬理化特性与香气的综合得分进行评价。结果显示：电子鼻PCA分析能较好的区分不同品种柠檬,GC-MS/O检测出65种挥发性风味组分,分别为烯类（46种）、醛类（6种）、醇类（5种）、酯类（5种）、酮类（2种）和酚类（1种）。不同品种柠檬中相对香气活度值（ROAV）大于1的风味组分有柠檬烯、合金欢烯、芳樟醇、桉叶油醇、辛醛、壬醛、柠檬醛以及癸醛8种,确定为其关键香气成分。安岳黄柠檬综合得分最高、香水柠檬次之,表明安岳黄柠檬理化特性以及香气较好。该研究可应用于柠檬溯源鉴定与柠檬品质分析,为柠檬综合利用提供理论支持。     

Smoke constituent exposure and smoking topography of adolescent daily cigarette smokers.

Adolescent smoking prevalence is a major health concern, with 24.4% reporting smoking in the past 30 days and 15.8% considered daily smokers. The purpose of this study was to characterize biobehavioral nicotine dependence, smoke constituent exposure and smoking topography in adolescent daily smokers. Relationships among biological markers of nicotine dependence (nicotine boost, carbon monoxide [CO] boost and cotinine levels) with existing self-report measures (modified Fagerstr?m Tolerance Questionnaire [mFTQ] and the motivations for smoking scale) were examined. Gender differences were characterized. Fifty adolescents 13-18 years old were recruited for the study, 50% female. CO, plasma nicotine levels pre- and postcigarette, cotinine, and smoking topography were measured during a smoking bout with participant's usual cigarette. Average CO boost, pre- to postcigarette was 7.2 + 3.6 ppm, baseline cotinine level averaged 224.0 +/- 169.6 ng/ml and nicotine boost averaged 23.4 +/- 21.7 ng/ml. Mean puffs per cigarette was 14.2 +/- 6.3. Males had significantly higher total puff volumes, but similar smoke constituent exposure to females, and higher handling of cigarettes as smoking motive. In regression analysis, 35% of variance in tobacco use, as indicated by baseline cotinine concentration, was explained by maximum puff duration, postcigarette CO level, and nicotine dependence, as measured by the mFTQ. Results indicated adolescents had considerable smoke constituent exposure and nicotine dependence suggesting the importance of appropriate smoking cessation treatment.