Tobacco smoking and somatic mutations in human bronchial epithelium.

Tobacco smoking causes lung cancer1-3, a process that is driven by more than 60 carcinogens in cigarette smoke that directly damage and mutate DNA4,5. The profound effects of tobacco on the genome of lung cancer cells are well-documented6-10, 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.

Altered interictal saccadic reaction time in migraine: a cross-sectional study.

AIMS: The underlying mechanisms of migraine remain poorly understood, partly because we lack objective methods for quantitative analysis of neurological function. To address this issue, we measured interictal saccadic latency in migraineurs and controls. METHODS: In a cross-sectional study, we compared interictal saccadic latency distributions of 12,800 saccades in 32 migraineurs with 32 age- and sex-matched controls. RESULTS: The variability of migraineurs' reaction time distributions was significantly smaller (σ = 1.01 vs. 1.13; p < 0.05) compared with controls. In addition, a smaller proportion of migraineurs generated 'early' saccades (31% vs. 56%: p < 0.05). Sensitivity/specificity analysis demonstrated the potential benefit of this technique to diagnostic discrimination. CONCLUSIONS: The migraineur's brain behaves significantly differently from that of a control during the interictal period. By analysing whole distributions, rather than just means, data can be related directly to current neurophysiological models: specifically, the observed decrease in variability suggests a functional deficit in the noradrenergic systems influencing the cerebral cortex. From a clinical perspective, this novel method of characterising neurological function in migraine is more rapid, practicable, inexpensive, objective and quantitative than previous methods such as evoked potentials and transcranial magnetic stimulation, and has the potential both to improve current diagnostic discrimination and to help guide future research into the underlying neural mechanisms.

Immune Surveillance in Clinical Regression of Preinvasive Squamous Cell Lung Cancer.

Before squamous cell lung cancer develops, precancerous lesions can be found in the airways. From longitudinal monitoring, we know that only half of such lesions become cancer, whereas a third spontaneously regress. Although recent studies have described the presence of an active immune response in high-grade lesions, the mechanisms underpinning clinical regression of precancerous lesions remain unknown. Here, we show that host immune surveillance is strongly implicated in lesion regression. Using bronchoscopic biopsies from human subjects, we find that regressive carcinoma in situ lesions harbor more infiltrating immune cells than those that progress to cancer. Moreover, molecular profiling of these lesions identifies potential immune escape mechanisms specifically in those that progress to cancer: antigen presentation is impaired by genomic and epigenetic changes, CCL27-CCR10 signaling is upregulated, and the immunomodulator TNFSF9 is downregulated. Changes appear intrinsic to the carcinoma in situ lesions, as the adjacent stroma of progressive and regressive lesions are transcriptomically similar. SIGNIFICANCE: Immune evasion is a hallmark of cancer. For the first time, this study identifies mechanisms by which precancerous lesions evade immune detection during the earliest stages of carcinogenesis and forms a basis for new therapeutic strategies that treat or prevent early-stage lung cancer.See related commentary by Krysan et al., p. 1442.This article is highlighted in the In This Issue feature, p. 1426.

Informed consent for interventions in stable coronary artery disease: problems, etiologies, and solutions.

The objective of this review was to determine whether patients undergoing percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) (1) understand the aims of the proposed intervention, and (2) whether they are offered alternative and potentially more effective therapies, as required for the process of informed consent. We performed a systematic review of Medline for observational studies of patient understanding and perceptions of coronary revascularization and of the consent process. Data extraction was of patient perceptions of expected symptomatic and prognostic benefits of PCI and CABG, and the proportion of patients offered potential alternative treatments. Eight studies were identified, of which seven were relevant to PCI and three to CABG. On average, 55% of patients correctly believed that PCI would improve symptoms, while 78% erroneously believed that PCI would extend life expectancy and 71% erroneously believed PCI would prevent future myocardial infarction. On average, over 80% of patients correctly identified that CABG would improve symptoms, reduce the risk of myocardial infarction and extend life expectancy. In the three studies that examined whether alternative therapies were discussed, 68% of PCI patients and 59% of CABG patients reported no such discussion. In conclusion, a large proportion of patients undergoing coronary interventions do not appear to understand the rationale for treatment and have erroneous perceptions regarding expected benefits. Moreover, patients are frequently not offered potentially more effective alternative therapies. This raises important questions about the adequacy of the current informed consent process. We recommend a multidisciplinary team approach as the most obvious way to remedy current practice.