Differential effects of heat-not-burn and conventional cigarettes on coronary flow, myocardial and vascular function.
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ABSTRACT:
SUBMITTER: Ikonomidis I
PROVIDER: S-EPMC8175445 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:With conventional cigarettes, the burning cone reaches temperatures of >900 °C, resulting in the production of numerous toxicants and significant levels of highly reactive free radicals. In attempts to eliminate combustion while still delivering nicotine and flavorings, a newer alternative tobacco product has emerged known as "heat-not-burn" (HnB). These products heat tobacco to temperatures of 250-350 °C depending on the device allowing for the volatilization of nicotine and flavorants while potentially limiting the production of combustion-related toxicants. To better understand how the designs of these new products compare to conventional cigarettes and different styles of electronic cigarettes (e-cigs), we measured and partially characterized their production of free radicals. Smoke or aerosols were trapped by a spin trap phenyl-N-tert-butylnitrone (PBN) and analyzed for free radicals using electron paramagnetic resonance (EPR). Free radical polarity was assessed by passing the aerosol or smoke through either a polar or nonpolar trap prior to being spin trapped with PBN. Particulate-phase radicals were detected only for conventional cigarettes. Gas-phase free radicals were detected in smoke/aerosol from all products with levels for HnB (IQOS, Glo) (12 pmol/puff) being similar to e-cigs (Juul, SREC, box mod e-cig) and hybrid devices (Ploom) (5-40 pmol/puff) but 50-fold lower than conventional cigarettes (1R6F). Gas phase radicals differed in polarity with HnB products and conventional cigarettes producing more polar radicals compared to those produced from e-cigs. Free radical production should be considered in evaluating the toxicological profile of nicotine delivery products and identification of the radicals is of paramount importance.
| S-EPMC9328730 | biostudies-literature
Project description:Aerosols from electronic cigarettes and heat-not-burn tobacco products have been found to contain lower levels of almost all compounds from the list of Harmful and Potentially Harmful Constituents known to be present in tobacco products and tobacco smoke than smoke from conventional cigarettes. Free radicals, which also pose potential health risks, are not considered in this list, and their levels in the different product types have not yet been compared under standardized conditions. We compared the type and quantity of free radicals in mainstream aerosol of 3R4F research cigarettes, two types of electronic cigarettes, and a heat-not-burn tobacco product. Free radicals and NO in the gas phases were separately spin trapped and quantified by electron paramagnetic resonance (EPR) spectroscopy by using a smoking machine for aerosol generation and a flow-through cell to enhance reproducibility of the quantification. Particulate matter was separated by a Cambridge filter and extracted, and persistent radicals were quantified by EPR spectroscopy. Levels of organic radicals for electronic cigarettes and the heat-not-burn product, as measured with the PBN spin trap, did not exceed 1% of the level observed for conventional cigarettes and were close to the radical level observed in air blanks. The radicals found in the smoke of conventional cigarettes were oxygen centered, most probably alkoxy radicals, whereas a signal for carbon-centered radicals near the detection limit was observed in aerosol from the heat-not-burn product and electronic cigarettes. The NO level in aerosol produced by electronic cigarettes was below our detection limit, whereas for the heat-not-burn product, it reached about 7% of the level observed for whole smoke from 3R4F cigarettes. Persistent radicals in particulate matter could be quantified only for 3R4F cigarettes. Aerosols from vaping and heat-not-burn tobacco products have much lower free radical levels than cigarette smoke, however, the toxicological implications of this finding are as yet unknown.
| S-EPMC6584902 | biostudies-literature
Project description:Nicotine exposure results in health risks not only for smokers but also for second- and third-hand smokers. Unraveling nicotine's degradation mechanism and the harmful chemicals that are produced under different conditions is vital to assess exposure risks. We performed a theoretical study to describe the early chemistry of nicotine degradation by investigating two important reactions that nicotine can undergo: hydrogen abstraction by hydroxyl radicals and unimolecular dissociation. The former contributes to the control of the degradation mechanism below 800 K due to a non-Arrhenius kinetics, which implies an enhancement of reactivity as temperature decreases. The latter becomes important at higher temperatures due to its larger activation energy. This change in the degradation mechanism is expected to affect the composition of vapors inhaled by smokers and room occupants. Conventional cigarettes, which operate at temperatures higher than 1000 K, are more prone to yield harmful pyridinyl radicals via nicotine dissociation, while nicotine in electronic cigarettes and vaporizers, with operating temperatures below 600 K, will be more likely degraded by hydroxyl radicals, resulting in a vapor with a different composition. Although low-temperature nicotine delivery devices have been claimed to be less harmful due to their nonburning operating conditions, the non-Arrhenius kinetics that we observed for the degradation mechanism below 873 K suggests that nicotine degradation may be more rapidly initiated as temperature is reduced, indicating that these devices may be more harmful than it is commonly assumed.
| S-EPMC8154610 | biostudies-literature
Project description:Background:Although the cause of acute eosinophilic pneumonia (AEP) has not yet been fully clarified, cigarette smoking is reported to be a risk factor for developing AEP. The heat-not-burn cigarette (HNBC) was developed to reduce the adverse effects of smoke on the user's surroundings. However, the health risks associated with HNBCs have not yet been clarified. We report a successfully treated case of fatal AEP presumably induced by HNBC use. Presentation of case:A 16-year-old man commenced HNBC smoking two weeks before admission and subsequently suffered from shortness of breath that gradually worsened. The patient was transferred to emergency department and immediately intubated because of respiratory failure. Computed tomography showed mosaic ground-glass shadows on the distal side of both lungs with a PaO2/FIO2 ratio of 76. The patient required veno-venous extracorporeal membrane oxygenation (ECMO) for severe respiratory failure. He was diagnosed with AEP by clinical course and detection of eosinophils in sputum; thus, methylprednisolone was administrated. The patient was weaned off ECMO four days after initiation and extubated the day after. He fully recovered without sequelae. Conclusion:As far as we know, our patient is the first case of AEP induced by HNBC use successfully treated with ECMO. Emergency physicians must be aware that HNBCs can induce fatal AEP.
| S-EPMC6288977 | biostudies-literature
Project description:Computational simulations of coronary artery blood flow, using anatomical models based on clinical imaging, are an emerging non-invasive tool for personalized treatment planning. However, current simulations contend with two related challenges - incomplete anatomies in image-based models due to the exclusion of arteries smaller than the imaging resolution, and the lack of personalized flow distributions informed by patient-specific imaging. We introduce a data-enabled, personalized and multi-scale flow simulation framework spanning large coronary arteries to myocardial microvasculature. It includes image-based coronary models combined with synthetic vasculature for arteries below the imaging resolution, myocardial blood flow simulated using Darcy models, and systemic circulation represented as lumped-parameter networks. Personalized flow distributions and model parameters are informed by clinical CT myocardial perfusion imaging and cardiac function using surrogate-based optimization. We reveal substantial differences in flow distributions and clinical diagnosis metrics between the proposed personalized framework and empirical methods based on anatomy; these errors cannot be predicted a priori. This suggests virtual treatment planning tools would benefit from increased personalization informed by emerging imaging methods.
| S-EPMC10462196 | biostudies-literature
Project description:ObjectivesIn addition to electronic cigarettes (e-cigarettes), tobacco companies have recently begun to sell heat-not-burn tobacco products, Ploom and iQOS in Japan. Previous research has reported an inverse association between combustible cigarette smoking and educational attainment, but little is known about the association for e-cigarettes, especially heat-not-burn tobacco products. Our objective was to analyze the relationship between educational attainment and e-cigarette and heat-not-burn tobacco use.SettingAn internet survey (randomly sampled research agency panelists) in Japan.ParticipantsA total of 7338 respondents aged 18-69 years in 2015 (3632 men and 3706women).Primary measuresAdjusted odds ratios (ORs) of educational attainment for current smoking (combustible cigarettes), e-cigarette ever-use, and heat-not-burn ever-use were calculated by multivariable logistic regression models using covariates including socio-demographic factors. Stratified analyses according to smoking status (combustible cigarettes) were additionally performed for e-cigarette ever-use and heat-not-burn tobacco product ever-use.ResultsAssociations between educational attainment and e-cigarette ever-use or heat-not-burn tobacco ever-use are not straightforward, although these associations are not statistically significant except for one cell. For example, using "graduate school" education as a reference category, adjusted ORs for "high school" were 1.44 (95% confidence interval [CI]: 0.85-2.44) for e-cigarettes ever-use and 0.75 (95% CI:0.19-2.97) for heat-not-burn tobacco product ever-use. Among current smokers, compared with "graduate school" (reference), those with lower educational attainment showed 0.6 to 0.7 ORs for e-cigarette ever-use: e.g.,"4-year university"(OR = 0.54, 95% CI:0.24-1.24) and "high school" (OR = 0.69, 95% CI: 0.30-1.60). Among former smokers, lower education indicated higher ORs for both e-cigarettes and heat-not-burn tobacco ever-use.ConclusionsThis study provides baseline information on educational gradients of e-cigarette and heat-not-burn tobacco products, ever-use. As heat-not-burn tobacco products are increasing their market share in Japan, continuous monitoring of these products will be necessary.
| S-EPMC5766136 | biostudies-literature
Project description:BACKGROUND:From among the global public health concerns, smoking remains one of the most crucial challenges. Especially for adolescents, the increase in the use of electronic cigarettes is controversial, as its use may lead to established smoking. In Japan, where a unique tobacco regulation system exists, the heat-not-burn tobacco market has been growing. However, the prevalence and association of combustible cigarettes and new tobacco-related products have not yet been closely investigated among Japanese adolescents. This study aimed to clarify the prevalence of smoking among adolescents, including new types of tobacco-related products, and to compare the characteristics of their users. METHODS:The 2017 Lifestyle Survey of Adolescents is a nationally-representative survey collected in Japan. From the national school directory, 98 junior high schools and 86 high schools were randomly sampled throughout Japan. The students completed an anonymous questionnaire at school. We calculated the prevalence of use for each type of tobacco product. Then, the use of a combination of products and the characteristics of different types of products were examined. RESULTS:In total, 64,152 students from 48 junior high schools and 55 high schools were included the analysis (school response rate?=?56%, Mage?=?15.7?years, 53.9% boys). The age-adjusted rate of ever (current) use of electronic cigarettes was 2.1% (0.7%) in junior high school and 3.5% (1.0%) in high school; that of combustible cigarettes was 2.6% (0.6%) in junior high school and 5.1% (1.5%) in high school. The rate of heat-not-burn tobacco use was lower relative to other products: 1.1% (0.5%) in junior high school and 2.2% (0.9%) in high school. An examination of the combined use of the three products identified a high number of dual users. Comparisons between different types of users indicated different backgrounds for combustible cigarette users and new product users. CONCLUSIONS:The prevalence of new tobacco-alternative products is growing in popularity among Japanese adolescents. Dual use is common, and many adolescents use new products only. Moreover, e-cigarettes might attract a broader range of groups to smoking. Continuous monitoring and research are needed to investigate their influence as a possible gateway to tobacco smoking.
| S-EPMC7240931 | biostudies-literature
Project description:Tobacco cigarette (TC) smoking has never been lower in the United States, but electronic cigarette (EC) vaping has reached epidemic proportions among our youth. Endothelial dysfunction, as measured by flow-mediated vasodilation (FMD) is a predictor of future atherosclerosis and adverse cardiovascular events and is impaired in young TC smokers, but whether FMD is also reduced in young EC vapers is uncertain. The aim of this study in otherwise healthy young people was to compare the effects of acute and chronic tobacco cigarette (TC) smoking and electronic cigarette (EC) vaping on FMD. FMD was compared in 47 nonsmokers (NS), 49 chronic EC vapers, and 40 chronic TC smokers at baseline and then after EC vapers (n = 31) and nonsmokers (n = 47) acutely used an EC with nicotine (ECN), EC without nicotine (EC0), and nicotine inhaler (NI) at ~4-wk intervals and after TC smokers (n = 33) acutely smoked a TC, compared with sham control. Mean age (NS, 26.3 ± 5.2 vs. EC, 27.4 ± 5.45 vs. TC, 27.1 ± 5.51 yr, P = 0.53) was similar among the groups, but there were more female nonsmokers. Baseline FMD was not different among the groups (NS, 7.7 ± 4.5 vs. EC:6.6 ± 3.6 vs. TC, 7.9 ± 3.7%∆, P = 0.35), even when compared by group and sex. Acute TC smoking versus control impaired FMD (FMD pre-/postsmoking, -2.52 ± 0.92 vs. 0.65 ± 0.93%∆, P = 0.02). Although the increase in plasma nicotine was similar after EC vapers used the ECN versus TC smokers smoked the TC (5.75 ± 0.74 vs. 5.88 ± 0.69 ng/mL, P = 0.47), acute EC vaping did not impair FMD. In otherwise healthy young people who regularly smoke TCs or ECs, impaired FMD compared with that in nonsmokers was not present at baseline. However, FMD was significantly impaired after smoking one TC, but not after vaping an equivalent "dose" (estimated by change in plasma nicotine) of an EC, consistent with the notion that non-nicotine constituents in TC smoke mediate the impairment. Although it is reassuring that acute EC vaping did not acutely impair FMD, it would be dangerous and premature to conclude that ECs do not lead to atherosclerosis.NEW & NOTEWORTHY In our study of otherwise healthy young people, baseline flow-mediated dilation (FMD), a predictor of atherosclerosis and increased cardiovascular risk, was not different among tobacco cigarette (TC) smokers or electronic cigarette (EC) vapers who had refrained from smoking, compared with nonsmokers. However, acutely smoking one TC impaired FMD in smokers, whereas vaping a similar EC "dose" (as estimated by change in plasma nicotine levels) did not. Finally, although it is reassuring that acute EC vaping did not acutely impair FMD, it would be premature and dangerous to conclude that ECs do not lead to atherosclerosis or increase cardiovascular risk.
| S-EPMC7509270 | biostudies-literature
Project description:Objectives- Coronary endothelial dysfunction is a precursor of atherosclerosis and adverse outcomes. Whether endothelial dysfunction is a localized or generalized phenomenon in humans remains uncertain. We simultaneously measured femoral and coronary vascular function with the hypothesis that peripheral vascular endothelial function will be reflective of coronary endothelial function. Approach and Results- Eighty-five subjects underwent coronary angiography for evaluation of chest pain or abnormal stress tests. Endothelium-dependent and -independent vascular function were measured using intracoronary and intrafemoral infusions of acetylcholine and sodium nitroprusside, respectively. Coronary flow reserve was assessed using intracoronary adenosine infusion. Flow velocity was measured in each circulation using a Doppler wire (FloWire, EndoSonics). Coronary vascular resistance and femoral vascular resistance were calculated as mean arterial pressure (mm Hg)/coronary blood flow (mL/min) and mean arterial pressure (mm Hg)/femoral average peak velocity (cm/s), respectively. Mean age was 53±11 years, 37% were female, 44% had hypertension, 12% had diabetes mellitus, and 38% had obstructive coronary artery disease. There was a correlation between the change in femoral vascular resistance with acetylcholine and acetylcholine-mediated changes in both the coronary vascular resistance ( r=0.27; P=0.014) and in the epicardial coronary artery diameter ( r=-0.25; P=0.021), indicating that subjects with normal endothelial function in the femoral circulation had normal endothelial function in the coronary epicardial and microcirculation and vice versa. The coronary vasodilator response to adenosine also correlated with the femoral vasodilatation with acetylcholine ( r=0.4; P=0.0002). There was no correlation between the coronary and femoral responses to sodium nitroprusside. Conclusions- Endothelial functional changes in the peripheral and coronary circulations were modestly correlated. Thus, peripheral microvascular endothelial function reflects endothelium-dependent coronary epicardial and microvascular function and the coronary flow reserve. Visual Overview- An online visual overview is available for this article.
| S-EPMC6594879 | biostudies-literature
Project description:BackgroundWomen with evidence of ischemia and no obstructive coronary arteries (INOCA) often have coronary microvascular dysfunction (CMD) indicated by impaired coronary flow reserve (CFR) to adenosine. Low CFR is associated with an adverse prognosis, including incident heart failure. Because the CFR calculation relies on the baseline intrinsic coronary vasomotor flow velocity, a major determinate of CFR and the degree of variation in baseline flow alone may be an important contributor to risk of adverse outcomes in women with CMD. A better understanding of baseline blood flow in the setting of low CFR and its association with myocardial performance would be helpful.MethodsWe evaluated 74 women who underwent invasive coronary reactivity testing in the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study and had impaired CFR (<2.32). We assessed the relationship between coronary artery baseline average peak velocity (bAPV) at rest and cardiac magnetic resonance imaging measures of left ventricular (LV) structure and function.ResultsWhen stratified as low (<22 cm/s) versus high (≥22 cm/s) bAPV, there were no differences in cardiovascular risk factors, coronary plaque burden, or LV structure. However, low bAPV was associated with higher LV end-diastolic filling pressure (P = 0.04), lower LV ejection fraction (P = 0.001), and differences in late systolic and diastolic strain rates (P = 0.01 to 0.05).ConclusionsIn women with impaired CFR, low resting coronary flow velocity is associated with more adverse myocardial performance, which may contribute to risk for adverse outcomes and particularly heart failure in women with CMD.
| S-EPMC7195998 | biostudies-literature