Mainstream Tobacco Smoke Research Articles

Comparison between the mainstream smoke of eleven RYO tobacco brands and the reference tobacco 3R4F

In this study 11 commercial roll-your-own (RYO) tobacco brands sold in Spain and the reference tobacco 3R4F have been smoked and several components of the mainstream tobacco smoke have been analyzed. Cigarettes were prepared using commercial tubes, and were smoked under smoking conditions based on the ISO 3308. The gaseous and condensed fractions of the smoke from RYO brands and 3R4F have been analyzed and compared. RYO tobaccos, as opposed to 3R4F, present lower amounts of condensed products in the traps than in the filters. In general, RYO tobaccos also provide lower yields of most of the compounds detected in the gas fraction. The yield of CO is between 15.4 and 20.4 mg/cigarette. In most of the cases studied, RYO tobaccos deliver higher amounts of nicotine than the 3R4F tobacco. On average, the yield of the different chemical families of compounds appearing in the particulate matter retained in the cigarette filters tends to be around three times higher than those obtained from 3R4F, whereas similar values have been obtained in the particulate matter retained in the traps located after the filters. It can be concluded that RYO tobaccos are not less hazardous than the reference tobacco, which may be contrary to popular belief.

Tobacco exposure increased airway limitation in dogs with chronic cough

In the field of veterinary medicine, there are few reports regarding the incidence of respiratory diseases, including cancer of the nose and lung among pet animals with passive tobacco smoke...

DNA Adducts of the Tobacco Carcinogens 2-Amino-9H-pyrido[2,3-b]indole and 4-Aminobiphenyl Are Formed at Environmental Exposure Levels and Persist in Human Hepatocytes

Aromatic amines and structurally related heterocyclic aromatic amines (HAAs) are produced during the combustion of tobacco or during the high-temperature cooking of meat. Exposure to some of these chemicals may contribute to the etiology of several common types of human cancers. 2-Amino-9H-pyrido[2,3-b]indole (AαC) is the most abundant HAA formed in mainstream tobacco smoke: it arises in amounts that are 25-100 times greater than the levels of the arylamine, 4-aminobiphenyl (4-ABP), a human carcinogen. 2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) is a prevalent HAA formed in cooked meats. AαC and MeIQx are rodent carcinogens; however, their carcinogenic potency in humans is unknown. A preliminary assessment of the carcinogenic potential of these HAAs in humans was conducted by examining the capacity of primary human hepatocytes to form DNA adducts of AαC and MeIQx, in comparison to 4-ABP, followed by the kinetics of DNA adduct removal by cellular enzyme repair systems. The principal DNA adducts formed were N-(deoxyguanosin-8-yl) (dG-C8) adducts. Comparable levels of DNA adducts were formed with AαC and 4-ABP, whereas adduct formation was ∼5-fold lower for MeIQx. dG-C8-AαC and dG-C8-4-ABP were formed at comparable levels in a concentration-dependent manner in human hepatocytes treated with procarcinogens over a 10,000-fold concentration range (1 nM-10 μM). Pretreatment of hepatocytes with furafylline, a selective inhibitor of cytochrome P450 1A2, resulted in a strong diminution of DNA adducts signifying that P450 1A2 is a major P450 isoform involved in bioactivation of these procarcinogens. The kinetics of adduct removal varied for each hepatocyte donor. Approximately half of the DNA adducts were removed within 24 h of treatment; however, the remaining lesions persisted over 5 days. The high levels of AαC present in tobacco smoke and its propensity to form persistent DNA adducts in human hepatocytes suggest that AαC can contribute to DNA damage and the risk of hepatocellular cancer in smokers.

Analysis of mainstream tobacco smoke by SPME-GC×GC-TOFMS

Tobacco smoke is an extremely complex and dynamic aerosol consisting of liquid/solid droplets (particulate phase) suspended in a mixture of gases and semi-volatiles (gaseous phase). It is formed during overlapping processes of burning, pyrolysis, pyrosynthesis, distillation, sublimation, condensation, filtration and elution . Smoke is emitted either as the mainstream smoke inhaled by the smoker or emitted from the smoldering cigarette in the form of sidestream smoke. Mainstream smoke consists of about 5600 identified compounds 2 and some reports claim the number of unidentified compounds might reach up to 100 000 . Mainstream tobacco smoke has been analyzed by means of comprehensive twodimensional gas chromatography coupled to time of flight mass spectrometry (GC×GCTOFMS), which is an established analytical technique for the characterization of complex mixtures of volatiles. Samples were analyzed after solid-phase microextraction (SPME) followed by thermal desorption (TD). This research focuses on the development of a strategy for the analysis of large numbers of samples from different tobacco formulations. Efforts are directed to the estimation of the relative importance of intra-product variation compared to inter-product variation, to evaluate how powerful the technique is for distinguishing quantitative or qualitative differences between samples. The statistical comparison is used for highlighting possible significant variations inside specific classes of compounds.

Cigarette smoke induces methylation of the tumor suppressor gene NISCH

We have previously identified a putative tumor suppressor gene, NISCH, whose promoter is methylated in lung tumor tissue as well as in plasma obtained from lung cancer patients. NISCH was observed to be more frequently methylated in smoker lung cancer patients than in non-smoker lung cancer patients. Here, we investigated the effect of tobacco smoke exposure on methylation of the NISCH gene. We tested methylation of NISCH after oral keratinocytes were exposed to mainstream and side stream cigarette smoke extract in culture. Methylation of the promoter region of the NISCH gene was also evaluated in plasma obtained from lifetime non-smokers and light smokers (< 20 pack/year), with and without lung tumors, and heavy smokers (20+ pack/year) without disease. Promoter methylation of NISCH was tested by quantitative fluorogenic real-time PCR in all samples. Promoter methylation of NISCH occurred after exposure to mainstream tobacco smoke as well as to side stream tobacco smoke in normal oral keratinocyte cell lines. NISCH methylation was also detected in 68% of high-risk, heavy smokers without detectable tumors. Interestingly, in light smokers, NISCH methylation was present in 69% of patients with lung cancer and absent in those without disease. Our pilot study indicates that tobacco smoke induces methylation changes in the NISCH gene promoter before any detectable cancer. Methylation of the NISCH gene was also found in lung cancer patients’ plasma samples. After confirming these findings in longitudinally collected plasma samples from high-risk populations (such as heavy smokers), examining patients for hypermethylation of the NISCH gene may aid in identifying those who should undergo additional screening for lung cancer.

Analysis and Impact of Mainstream Tobacco Smoke from Regular and Reduced Exposure Products on Blood Brain Barrier: Are we clearing this smoke cloud yet?

Active and passive tobacco smoking (TS) are associated with dysfunction of vascular endothelial physiology (including the blood‐brain barrier) in a causative and dose dependent way largely related to the relative content of reactive oxygen and nitrogen species (ROS/RNS). ROS and RNS can mediate progressive endothelial damage causing alteration of extracellular matrix and apoptosis of endothelial cells. Accordingly, the tobacco industry is marketing several lines of “reduced‐exposure” (RE) tobacco products claimed to be less harmful. For this purpose we measured the ROS and nitrogen content of mainstream TS from different brands (including tobacco free and ultralight cigarettes) and assessed their effect on BBB endothelial cells. Our results showed that RE products have a higher content of hydrogen peroxide and RNS which correlated with higher release of MMP‐2 and IL‐6 from the BBB endothelium. These results were further supported by gene array analysis which also showed alterations in the gene expression of CYP enzymes, vascular adhesion molecules and signal transduction proteins (SHC4). Alteration in gene expression of hydroxysteroid (11‐beta) dehydrogenase 1 and 2, insulin induced gene 1, also suggests that TS could play a role in the pathogenesis of type 2 diabetes. Our results suggest that ‘light’ and ‘tobacco free’ cigarettes are equally or potentially more toxic than the regular products.This work was supported by NIH/NIDA R01‐DA029121–01A1 and A.R.D.F. to Dr. Luca Cucullo.

Analysis of mainstream tobacco smoke particulate phase using comprehensive two‐dimensional gas chromatography time‐of‐flight mass spectrometry

Comprehensive 2D GC coupled to time-of-flight mass spectrometry was applied for the characterization of the particulate phase of mainstream tobacco smoke particulate. Five 3R4F research cigarettes were smoked on a rotary smoking machine under standardized conditions, total particular matter was collected on Cambridge filter pads and extracted using methanol-based liquid extraction and dynamic headspace (DHS) approaches. Automated peak finding and mass spectral deconvolution combined with scripting and manual revision of library hits were used to evaluate the library search results. The revised peak table contained nearly 1800 individual compounds for the DHS sample and over 900 for the solvent extracted sample. These methods of extraction were shown to be complementary, leading to only 11% of repeated analytes, and their combination gave rise to a list of almost 2500 individual compounds.

Influence of Steryl Esters on the Delivery of Polycyclic Aromatic Hydrocarbons in Tobacco Mainstream Smoke

Influence of Steryl Esters on the Delivery of Polycyclic Aromatic Hydrocarbons in Tobacco Mainstream Smoke

The effect of long term storage on tobacco smoke particulate matter in in vitro genotoxicity and cytotoxicity assays

Particulate matter (PM) collected from mainstream tobacco smoke is a test article commonly used for in vitro genotoxicity and cytotoxicity testing of combustible tobacco products. However, little published data exists concerning the stability of PM. We completed a 2year study to quantify the effect of PM storage at −80°C, on the genotoxicity and cytotoxicity of PM generated from 3R4F and M4A reference cigarettes. The Ames test, Micronucleus assay (MNvit), Mouse Lymphoma assay (MLA) and the Neutral Red Uptake assay (NRU) were used. The majority of M4A and 3R4F PMs were genotoxic and cytotoxic at the timepoints tested. Some minor but statistically significant differences were observed for stored versus freshly prepared PM, but the magnitude of changes were within the variability observed for repeat testing.

Abstract CN06-02: Epigenetic Deregulation of MicroRNAs During Tobacco Carcinogen-Induced Transformation of Bronchial Epithelial Cells

Abstract Epigenetic silencing of genes and microRNAs (miRs) via chromatin remodeling and cytosine methylation has emerged as a major mechanism in lung cancer etiology. The reversal of gene and miR silencing using pharmacological agents by affecting cytosine-DNA methyltransferases (DNMTs), histone methyltransferases (HMTs), or histone deacetylases (HDACs) offers new strategies for prevention and intervention for lung cancer. We have developed an in vitro model using hTERT/cdk4 immortalized human bronchial epithelial cell lines (HBECs) that identifies molecular changes driving transformation of preneoplastic lung epithelial cells during exposure to carcinogens found in mainstream and environmental tobacco smoke. Our studies provided a mechanistic link between increased DNMT1 protein, de novo methylation of genes, and reduced DNA repair capacity that together seemed causal for transformation. Our recent studies show that the exposure of HBECs to carcinogens for 4 wk induces a persistent and irreversible, multifaceted dedifferentiation program characterized by the epithelial-to-mesenchymal transition (EMT). EMT induction was epigenetically driven, initially by chromatin remodeling involving H3K27me3 enrichment, with ensuing DNA methylation sustaining the silencing of miR-200b, -200c, and -205 implicated in this developmental program and persisting in malignant tumors. Over expression of these miRs reversed transformation. Next generation sequencing of transformed HBEC lines has identified 25 miRs whose silencing may be regulated through chromatin remodeling and promoter methylation. The impact of specific miRs identified by sequencing on transformation, regulation by chromatin, and their prevalence in lung cancer will be described. (Supported by R01 ES008801 and P50 CA58184). Citation Format: Steven A. Belinsky, Avrum Spira, Carmen Tellez. Epigenetic deregulation of microRNAs during tobacco carcinogen-induced transformation of bronchial epithelial cells. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr CN06-02.

The Effects of Mainstream and Sidestream Environmental Tobacco Smoke Composition for Enhanced Condensational Droplet Growth by Water Vapor

Although tobacco smoke is well known for its adverse health effects, the hygroscopicity and droplet growth properties of the aerosol have not been thoroughly explored. In this study, cigarette smoke is further characterized and several state-of-art analysis techniques are applied to understand the effects of particle chemistry and hygroscopicity for enhanced condensational growth (ECG) by water vapor and wet particle deposition. Low nicotine (LN) and ultra-low nicotine (ULN) research cigarettes are tested with a Walton Smoking Machine (WSM); mainstream and sidestream environmental tobacco smoke (ETS) are produced. Online and offline analysis are combined to analyze the smoke. More than 99% of the mainstream and sidestream ETS mass is semivolatile aerosol and nonelemental carbon, of which more than 95% is organic. The water-soluble organic comprises 30-85% of the aerosol mass fraction and has no effect on surface tension when dissolved in water. The oxygen-to-carbon ratio (O/C) and nitrogen-to-carbon ratio (N/C) from High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS or HR-AMS) data show that more oxidized components are present in mainstream smoke. Differences in the bulk aerosol composition have little effect on the overall water uptake. The two types of cigarettes produce aerosols of similar hygroscopicity (with single hygroscopicity parameter, κ ∼0.15 or less) in mainstream and sidestream smoke. Droplets grow at the same rate within the instrument. However, ULN reference cigarettes that produce dry particles at larger sizes are more likely to experience ECG. Copyright 2012 American Association for Aerosol Research

Differences between mainstream and sidestream tobacco smoke extracts and nicotine in the activation and aggregation of platelets subjected to cardiovascular conditions in diabetes

Mainstream and sidestream tobacco smoke extracts have been shown to increase platelet activation directly. Furthermore, advanced glycation end products, which are present in the diabetic vasculature, have also been shown to enhance platelet activity. However, the combined effects of these two risk factors on platelet functions remain unclear. Platelets were exposed to tobacco extracts concurrently with advanced glycation end products. Timed samples were removed to assess the extent of platelet activity. The presence of smoke extracts enhanced platelet activity as compared to control conditions, this was especially prevalent for sidestream extracts. With the addition of irreversibly glycated albumin, there was an additive effect, further enhancing platelet responses. This was at least partially regulated by α-granule release and CD41 expression. The combination of cardiovascular risk factors can significantly enhance platelet activation and aggregation, and therefore it is possible to accelerate cardiovascular diseases through the interactions of multiple cardiovascular risk factors.

The Fate of Maleic Hydrazide on Tobacco during Smoking

Tobacco mainstream smoke (MSS) and sidestream smoke (SSS), butts, and ashes from commercial cigarettes and maleic hydrazide (MH) spiked cigarettes were analyzed for their MH contents. The MH transfer rates obtained for MSS ranged from 1.4% to 3.7%, for SSS ranged from 0.2% to 0.9%, and for butts ranged from 1.1% to 1.9%. And as expected, MH is absent in ashes. The transfer rate of MH into mainstream smoke is the top one during in transfer rate into main-stream, side-stream, ashes, and butts, and higher MH levels lead to more MH in smoke. Further, analysis of total MH in butts and ashes along with that in MSS and SSS indicates that much MH is destructed during the smoking process.

Analysis of Markers of Exposure to Constituents of Environmental Tobacco Smoke (ETS)

Tobacco smoke is a complex mixture of more than 4000 chemical compounds, many of which are harmful to human health. These compounds belong to various chemical classes, including amides, imides, lactams, carboxylic acids, aldehydes, ketones, alcohols, phenols, amines, hydrocarbons, ethers, and inorganic compounds. There are three types of tobacco smoke streams: the mainstream, the sidestream, and environmental tobacco smoke (ETS). In view of the threat to human health resulting from exposure to either of these tobacco smoke streams or to ETS, it has become necessary to monitor levels of substances characteristic of tobacco smoke, i.e., “biomarkers,” The biomonitoring of toxic substances involves the analysis of biological materials taken from human subjects (urine, saliva, placenta, sweat, blood) for the presence of selected biomarkers. This article presents information on sample preparation techniques and analytical methodologies applicable in the analysis of biological materials for the presence of biomarkers and also on the levels of biomarkers present in samples of biological material taken from people exposed to various degrees to the harmful actions of substances present in tobacco smoke.

Sub-chronic exposure to second hand smoke induces airspace leukocyte infiltration and decreased lung elastance

Exposure to second hand tobacco smoke is associated with the development and/or exacerbation of several different pulmonary diseases in humans. To better understand the possible effects of second hand smoke exposure in humans, we sub-chronically (4 weeks) exposed mice to a mixture of mainstream and sidestream tobacco smoke at concentrations similar to second hand smoke exposure in humans. The inflammatory response to smoke exposures was assessed at the end of this time by enumeration of pulmonary leukocyte infiltration together with measurements of lung elastance and pathology. This response was measured in both healthy wild type (C57BL/6) mice as well as mouse mutants deficient in the expression of Arhgef1 (Arhgef1−/−) that display constitutive pulmonary inflammation and decreased lung elastance reminiscent of emphysema. The results from this study show that sub-chronic second hand smoke exposure leads to significantly increased numbers of airspace leukocytes in both healthy and mutant animals. While sub-chronic cigarette smoke exposure is not sufficient to induce changes in lung architecture as measured by mean linear intercept, both groups exhibit a significant decrease in lung elastance. Together these data demonstrate that even sub-chronic exposure to second hand smoke is sufficient to induce pulmonary inflammation and decrease lung elastance in both healthy and diseased animals and in the absence of tissue destruction.

Sidestream tobacco smoke is a male germ cell mutagen

Active cigarette smoking increases oxidative damage, DNA adducts, DNA strand breaks, chromosomal aberrations, and heritable mutations in sperm. However, little is known regarding the effects of second-hand smoke on the male germ line. We show here that short-term exposure to mainstream tobacco smoke or sidestream tobacco smoke (STS), the main component of second-hand smoke, induces mutations at an expanded simple tandem repeat locus (Ms6-hm) in mouse sperm. We further show that the response to STS is not linear and that, for both mainstream tobacco smoke and STS, doses that induced significant increases in expanded simple tandem repeat mutations in sperm did not increase the frequencies of micronucleated reticulocytes and erythrocytes in the bone marrow and blood of exposed mice. These data show that passive exposure to cigarette smoke can cause tandem repeat mutations in sperm under conditions that may not induce genetic damage in somatic cells. Although the relationship between noncoding tandem repeat instability and mutations in functional regions of the genome is unclear, our data suggest that paternal exposure to second-hand smoke may have reproductive consequences that go beyond the passive smoker.

The Effect of Cigarette Design on the Content of Phenols in Mainstream Tobacco Smoke

Abstract The influence of cigarette design on the content of phenols in mainstream tobacco smoke was studied. The most abundant phenols - catechol, hydroquinone, phenol, o-, m-, and p-cresol, and resorcinol - were determined by HPLC with fluorescence detection. Hydroquinone and catechol made the most significant contribution to the total content of phenols with maximum values of 135.0 µg/cig and 95.7 µg/cig, respectively. The highest total content of phenols (330.9 µg/cig) was measured in the smoke of a Virginia tobacco cigarette. The total content of phenols (µg/cig) in cigarette mainstream smoke decreased linearly with increased filter ventilation, R2 = 0.9536. The results obtained indicate that filtration and ventilation can strongly influence the mainstream tobacco smoke content of phenol and its less polar derivatives, o-, m-, and p-cresol, which were reduced by up to 85%. Hydroquinone and catechol are less affected and only cigarettes with the special “recessed charcoal filter system” and cigarettes with filter ventilation over 50% showed significant reductions. On a per mg ‘tar’ basis the largest contributor to phenols in cigarette mainstream smoke was the selection of the tobacco type. The use of any standard commercial filter on an unfiltered cigarette can substantially reduce the yield of phenols in cigarette mainstream smoke. The use of special filters (e.g., the “recessed charcoal filter system”) or high levels of cigarette ventilation does not reduce the amount of phenols in tobacco smoke considerably when normalized on a per mg ‘tar’ basis.

Abstract ED02-03: Gene, environment, and risk factor interaction in pancreatic cancer

Abstract ED02-03: Gene, environment, and risk factor interaction in pancreatic cancer

Rebuttal to Comment on Gas/Particle Partitioning of Two Acid−Base Active Compounds in Mainstream Tobacco Smoke: Nicotine and Ammonia

Rebuttal to Comment on Gas/Particle Partitioning of Two Acid−Base Active Compounds in Mainstream Tobacco Smoke: Nicotine and Ammonia

Comment on Gas/Particle Partitioning of Two Acid−Base Active Compounds in Mainstream Tobacco Smoke: Nicotine and Ammonia

Comment on Gas/Particle Partitioning of Two Acid−Base Active Compounds in Mainstream Tobacco Smoke: Nicotine and Ammonia