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"Tobacco smoking"
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Tobacco smoking and somatic mutations in human bronchial epithelium
Tobacco smoking causes lung cancer
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, a process that is driven by more than 60 carcinogens in cigarette smoke that directly damage and mutate DNA
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. The profound effects of tobacco on the genome of lung cancer cells are well-documented
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, but equivalent data for normal bronchial cells are lacking. Here we sequenced whole genomes of 632 colonies derived from single bronchial epithelial cells across 16 subjects. Tobacco smoking was the major influence on mutational burden, typically adding from 1,000 to 10,000 mutations per cell; massively increasing the variance both within and between subjects; and generating several distinct mutational signatures of substitutions and of insertions and deletions. A population of cells in individuals with a history of smoking had mutational burdens that were equivalent to those expected for people who had never smoked: these cells had less damage from tobacco-specific mutational processes, were fourfold more frequent in ex-smokers than current smokers and had considerably longer telomeres than their more-mutated counterparts. Driver mutations increased in frequency with age, affecting 4–14% of cells in middle-aged subjects who had never smoked. In current smokers, at least 25% of cells carried driver mutations and 0–6% of cells had two or even three drivers. Thus, tobacco smoking increases mutational burden, cell-to-cell heterogeneity and driver mutations, but quitting promotes replenishment of the bronchial epithelium from mitotically quiescent cells that have avoided tobacco mutagenesis.
Whole-genome sequencing of normal bronchial epithelium from 16 individuals shows that tobacco smoking increases genomic heterogeneity, mutational burden and driver mutations, whereas stopping smoking promotes replenishment of the epithelium with near-normal cells.
Journal Article
Electronic cigarettes for smoking cessation: a randomised controlled trial
Electronic cigarettes (e-cigarettes) can deliver nicotine and mitigate tobacco withdrawal and are used by many smokers to assist quit attempts. We investigated whether e-cigarettes are more effective than nicotine patches at helping smokers to quit.
We did this pragmatic randomised-controlled superiority trial in Auckland, New Zealand, between Sept 6, 2011, and July 5, 2013. Adult (≥18 years) smokers wanting to quit were randomised (with computerised block randomisation, block size nine, stratified by ethnicity [Māori; Pacific; or non-Māori, non-Pacific], sex [men or women], and level of nicotine dependence [>5 or ≤5 Fagerström test for nicotine dependence]) in a 4:4:1 ratio to 16 mg nicotine e-cigarettes, nicotine patches (21 mg patch, one daily), or placebo e-cigarettes (no nicotine), from 1 week before until 12 weeks after quit day, with low intensity behavioural support via voluntary telephone counselling. The primary outcome was biochemically verified continuous abstinence at 6 months (exhaled breath carbon monoxide measurement <10 ppm). Primary analysis was by intention to treat. This trial is registered with the Australian New Zealand Clinical Trials Registry, number ACTRN12610000866000.
657 people were randomised (289 to nicotine e-cigarettes, 295 to patches, and 73 to placebo e-cigarettes) and were included in the intention-to-treat analysis. At 6 months, verified abstinence was 7·3% (21 of 289) with nicotine e-cigarettes, 5·8% (17 of 295) with patches, and 4·1% (three of 73) with placebo e-cigarettes (risk difference for nicotine e-cigarette vs patches 1·51 [95% CI −2·49 to 5·51]; for nicotine e-cigarettes vs placebo e-cigarettes 3·16 [95% CI −2·29 to 8·61]). Achievement of abstinence was substantially lower than we anticipated for the power calculation, thus we had insufficient statistical power to conclude superiority of nicotine e-cigarettes to patches or to placebo e-cigarettes. We identified no significant differences in adverse events, with 137 events in the nicotine e-cigarettes group, 119 events in the patches group, and 36 events in the placebo e-cigarettes group. We noted no evidence of an association between adverse events and study product.
E-cigarettes, with or without nicotine, were modestly effective at helping smokers to quit, with similar achievement of abstinence as with nicotine patches, and few adverse events. Uncertainty exists about the place of e-cigarettes in tobacco control, and more research is urgently needed to clearly establish their overall benefits and harms at both individual and population levels.
Health Research Council of New Zealand.
Journal Article
Gut bacteria alleviate smoking-related NASH by degrading gut nicotine
Tobacco smoking is positively correlated with non-alcoholic fatty liver disease (NAFLD)
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, but the underlying mechanism for this association is unclear. Here we report that nicotine accumulates in the intestine during tobacco smoking and activates intestinal AMPKα. We identify the gut bacterium
Bacteroides xylanisolvens
as an effective nicotine degrader. Colonization of
B. xylanisolvens
reduces intestinal nicotine concentrations in nicotine-exposed mice, and it improves nicotine-exacerbated NAFLD progression. Mechanistically, AMPKα promotes the phosphorylation of sphingomyelin phosphodiesterase 3 (SMPD3), stabilizing the latter and therefore increasing intestinal ceramide formation, which contributes to NAFLD progression to non-alcoholic steatohepatitis (NASH). Our results establish a role for intestinal nicotine accumulation in NAFLD progression and reveal an endogenous bacterium in the human intestine with the ability to metabolize nicotine. These findings suggest a possible route to reduce tobacco smoking-exacerbated NAFLD progression.
Nicotine accumulates in the intestine during tobacco smoking and accelerates the progression of non-alcoholic fatty liver disease to non-alcoholic steatohepatitis (NASH), but it can be degraded effectively by the human symbiont
Bacteroides xylanisolvens.
Journal Article
The cigarette book : the history and culture of smoking
Arranged in dictionary format, a souvenir of the era in which the cigarette and everything about it was celebrated.
Book
21st-Century Hazards of Smoking and Benefits of Cessation in the United States
In this analysis of current data from a nationally representative U.S. survey, smoking was associated with a reduction in life expectancy of 10 years, and the excess risk was reduced by about 90% among smokers who quit by 40 years of age.
Smoking is a major cause of premature death worldwide.
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Despite substantial declines in the prevalence of smoking by adults, estimates based on extrapolation from studies in the 1980s suggest that for those between 35 and 69 years of age, smoking currently accounts for almost 200,000 deaths annually in the United States, or about one fourth of all deaths in this age group.
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The prevalence of smoking peaked around 1960 among U.S. men and about two decades later among U.S. women.
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Rates of death from vascular disease have decreased substantially since the 1980s owing to reductions in smoking . . .
Journal Article
Thioredoxin activity confers resistance against oxidative stress in tumor-infiltrating NK cells
To improve the clinical outcome of adoptive NK cell therapy in patients with solid tumors, NK cells need to persist within the tumor microenvironment (TME) in which the abundance of ROS could dampen antitumor immune responses. In the present study, we demonstrated that IL-15-primed NK cells acquired resistance against oxidative stress through the thioredoxin system activated by mTOR. Mechanistically, the activation of thioredoxin showed dependence on localization of thioredoxin-interacting protein. We show that NK cells residing in the tumor core expressed higher thiol densities that could aid in protecting other lymphocytes against ROS within the TME. Furthermore, the prognostic value of IL15 and the NK cell gene signature in tumors may be influenced by tobacco smoking history in patients with non-small-cell lung cancer (NSCLC). Collectively, the levels of reducing antioxidants in NK cells may not only predict better tumor penetrance but potentially even the immune therapy response.
Journal Article