Tobacco-Related Disease Research Program Funded Publication

Tobacco use remains the single most preventable cause of disease, disability, and death in the United States and in California. The Tobacco-Related Disease Research Program (TRDRP) is one of three entities that constitute California’s program to control tobacco consumption and alleviate the burden of tobacco-related disease. This effort was initiated by Proposition 99, “The Tobacco Tax and Health Protection Act of 1988” which mandated that the Department of Health Services, the Department of Education and the University of California be allocated a portion of the tobacco tax revenue collected to address issues of tobacco consumption and its consequences in the state. Enabling legislation requested that the University of California, in its role as the research arm of the state, “administer a comprehensive grant program to support research efforts related to the prevention, causes, and treatment of tobacco-related diseases” and that “ all qualified investigators, regardless of institutional affiliation, shall have equal access and opportunity to compete for the funds.”

The TRDRP is administered by the University of California and is a program of the Research Grants Program Office (RGPO), Office of Research and Graduate Studies at the University of California, Office of the President.

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Early-life tobacco exposure is causally implicated in aberrant RAG-mediated recombination in childhood acute lymphoblastic leukemia

(2024)

Cover page of Nicotine inhalant via E‐cigarette facilitates sensorimotor function recovery by upregulating neuronal BDNF–TrkB signalling in traumatic brain injury

Nicotine inhalant via E‐cigarette facilitates sensorimotor function recovery by upregulating neuronal BDNF–TrkB signalling in traumatic brain injury

(2024)

Background and purpose

Traumatic brain injury (TBI) causes lifelong physical and psychological dysfunction in affected individuals. The current study investigated the effects of chronic nicotine exposure via E-cigarettes (E-cig) (vaping) on TBI-associated behavioural and biochemical changes.

Experimental approach

Adult C57/BL6J male mice were subjected to controlled cortical impact (CCI) followed by daily exposure to E-cig vapour for 6 weeks. Sensorimotor functions, locomotion, and sociability were subsequently evaluated by nesting, open field, and social approach tests, respectively. Immunoblots were conducted to examine the expression of mature brain-derived neurotrophic factor (mBDNF) and associated downstream proteins (p-Erk, p-Akt). Histological analyses were performed to evaluate neuronal survival and neuroinflammation.

Key results

Post-injury chronic nicotine exposure significantly improved nesting performance in CCI mice. Histological analysis revealed increased survival of cortical neurons in the perilesion cortex with chronic nicotine exposure. Immunoblots revealed that chronic nicotine exposure significantly up-regulated mBDNF, p-Erk and p-Akt expression in the perilesion cortex of CCI mice. Immunofluorescence microscopy indicated that elevated mBDNF and p-Akt expression were mainly localized within cortical neurons. Immunolabelling of Iba1 demonstrated that chronic nicotine exposure attenuated microglia-mediated neuroinflammation.

Conclusions and implications

Post-injury chronic nicotine exposure via vaping facilitates recovery of sensorimotor function by upregulating neuroprotective mBDNF/TrkB/Akt/Erk signalling. These findings suggest potential neuroprotective properties of nicotine despite its highly addictive nature. Thus, understanding the multifaceted effects of chronic nicotine exposure on TBI-associated symptoms is crucial for paving the way for informed and properly managed therapeutic interventions.

“I’m both smoking and vaping”: a longitudinal qualitative study of US young adults who tried to quit smoking cigarettes by using electronic cigarettes

(2024)

Objective

To describe how young adults use electronic cigarettes (electronic nicotine delivery systems (ENDS)) for smoking cessation and reasons why they may or may not successfully quit smoking.

Methods

Longitudinal qualitative data were collected annually from 2017 to 2019 for 25 young adult tobacco users (aged 18-29 years) in California (USA) who used ENDS to quit/reduce smoking. Thematic and trajectory analyses were used to identify key within-person and between-person changes in tobacco/nicotine use over time.

Results

Five types of tobacco use transition were identified among baseline dual users of cigarettes and ENDS: sustained dual use without reduced smoking (n=8), transition to exclusive daily ENDS use (n=6), sustained dual use with reduced smoking (n=5), transition back to exclusive smoking (n=4) and transition to neither smoking nor vaping (n=2). Participants' ENDS use behaviour varied over time in terms of vaping quantity and device characteristics (eg, changing nicotine concentrations/flavours, switching between multiple devices). Three themes that related to successfully replacing cigarettes with ENDS were perceived positive physical effects, perceived satisfaction and enjoyment and context changes. Four themes for unsuccessful replacement were perceived negative physical discomforts, perceived addictiveness and harm, unsatisfactory substitution for cigarettes and device malfunction.

Conclusions

Young adults' experiences with using ENDS as a smoking cessation aid were highly variable. Adequate nicotine delivery and perceived safety and benefits contributed to successfully reducing or quitting cigarettes. Providing behavioural counselling and standardising ENDS products may enhance cessation for young adults.

Insurance Disparities in Quality of Care Among Patients With Head and Neck Cancer

(2024)

Importance

Significant insurance status disparities have been demonstrated in head and neck cancer (HNC) outcomes. The effects of insurance status on HNC outcomes may be explained by differential access to high-quality care.

Objective

To evaluate the association of insurance status with the quality of the treating hospital and receipt of guideline-compliant care among patients with HNC.

Design, setting, and participants

This retrospective cohort study of data from the California Cancer Registry dataset linked with discharge records and hospital characteristics from the California Department of Health Care Access and Information included adult patients with HNC diagnosed between January 1, 2010, and December 31, 2019. Data were analyzed from May 10, 2023, to March 25, 2024.

Exposures

Insurance status: commercial, Medicare, Medicaid, uninsured, other, or unknown.

Main outcomes and measures

Quality of the treating hospital (tertiles), receipt of National Comprehensive Cancer Network guideline-compliant care, and overall survival.

Results

A total of 23 933 patients (mean [SD] age, 64.8 [12.3] years; 75.3% male) met the inclusion criteria. Treatment in top-tertile hospitals (hazard ratio, 0.87; 95% CI, 0.79-0.95) was associated with improved overall survival compared with treatment in bottom-tertile hospitals. Medicare (odds ratio [OR], 0.78; 95% CI, 0.73-0.84), Medicaid (OR, 0.60; 95% CI, 0.54-0.66), and uninsured (OR, 0.38; 95% CI, 0.29-0.49) status were associated with lower likelihood of treatment in high-quality hospitals compared with commercial insurance. Among patients with advanced disease, Medicaid (OR, 0.72; 95% CI, 0.62-0.83) and uninsured (OR, 0.64; 95% CI, 0.44-0.93) patients were less likely to receive dual-modality therapy. Among patients with surgically resected advanced disease, Medicaid coverage (OR, 0.73; 95% CI, 0.58-0.93) was associated with lower likelihood of receiving adjuvant radiotherapy.

Conclusions and relevance

This study found significant insurance disparities in quality of care among patients with HNC. These findings highlight the need for continued health insurance reform in the US to improve the quality of insurance coverage, in addition to expanding access to health insurance.

Single-stranded pre-methylated 5mC adapters uncover the methylation profile of plasma ultrashort Single-stranded cell-free DNA

(2024)

Whole-genome bisulfite sequencing (BS-Seq) measures cytosine methylation changes at single-base resolution and can be used to profile cell-free DNA (cfDNA). In plasma, ultrashort single-stranded cfDNA (uscfDNA, ∼50 nt) has been identified together with 167 bp double-stranded mononucleosomal cell-free DNA (mncfDNA). However, the methylation profile of uscfDNA has not been described. Conventional BS-Seq workflows may not be helpful because bisulfite conversion degrades larger DNA into smaller fragments, leading to erroneous categorization as uscfDNA. We describe the '5mCAdpBS-Seq' workflow in which pre-methylated 5mC (5-methylcytosine) single-stranded adapters are ligated to heat-denatured cfDNA before bisulfite conversion. This method retains only DNA fragments that are unaltered by bisulfite treatment, resulting in less biased uscfDNA methylation analysis. Using 5mCAdpBS-Seq, uscfDNA had lower levels of DNA methylation (∼15%) compared to mncfDNA and was enriched in promoters and CpG islands. Hypomethylated uscfDNA fragments were enriched in upstream transcription start sites (TSSs), and the intensity of enrichment was correlated with expressed genes of hemopoietic cells. Using tissue-of-origin deconvolution, we inferred that uscfDNA is derived primarily from eosinophils, neutrophils, and monocytes. As proof-of-principle, we show that characteristics of the methylation profile of uscfDNA can distinguish non-small cell lung carcinoma from non-cancer samples. The 5mCAdpBS-Seq workflow is recommended for any cfDNA methylation-based investigations.

Early-life tobacco exposure is causally implicated in aberrant RAG-mediated recombination in childhood acute lymphoblastic leukemia

(2024)

Acute lymphoblastic leukemia (ALL) is the most common cancer in children, yet few environmental risk factors have been identified. We previously found an association between early-life tobacco smoke exposure and frequency of somatic deletions of 8 leukemia driver genes among childhood ALL patients in the California Childhood Leukemia Study. To expand analysis genome-wide and examine potential mechanisms, we conducted tumor whole-genome sequencing in 35 ALL patients, including 18 with high prenatal tobacco exposure and 17 with low exposure as determined by established epigenetic biomarkers. High tobacco exposure patients had significantly more structural variants (P < .001) and deletions (P = .001) genome-wide than low exposure patients. Investigation of off-target RAG recombination revealed that 41% of deletions in the high tobacco exposure patients were putatively RAG-mediated (full RAG motif identified at one or both breakpoints) compared with only 21% in the low exposure group (P = .001). In a multilevel model, deletions in high tobacco exposure patients were 2.44-fold (95% CI:1.13-5.38) more likely to be putatively RAG-mediated than deletions in low exposure patients. No point mutational signatures were associated with prenatal tobacco exposure. Our findings suggest that early-life tobacco smoke exposure may promote leukemogenesis by driving development of somatic deletions in pre-leukemic lymphocytes via off-target RAG recombination.

Quantification of Free Radicals from Vaping Electronic Cigarettes Containing Nicotine Salt Solutions with Different Organic Acid Types and Concentrations

(2024)

Electronic (e-) cigarette formulations containing nicotine salts from a range of organic acid conjugates and pH values have dominated the commercial market. The acids in the nicotine salt formulations may alter the redox environment in e-cigarettes, impacting free radical formation in e-cigarette aerosol. Here, the generation of aerosol mass and free radicals from a fourth-generation e-cigarette device was evaluated at 2 wt % nicotine salts (pH 7, 30:70 mixture propylene glycol to vegetable glycerin) across eight organic acids used in e-liquids: benzoic acid (BA), salicylic acid (SLA), lactic acid (LA), levulinic acid (LVA), succinic acid (SA), malic acid (MA), tartaric acid (TA), and citric acid (CA). Furthermore, 2 wt % BA nicotine salts were studied at the following nicotine to acid ratios: 1:2 (pH 4), 1:1 (pH 7), and 2:1 (pH 8), in comparison with freebase nicotine (pH 10). Radical yields were quantified by spin-trapping and electron paramagnetic resonance (EPR) spectroscopy. The EPR spectra of free radicals in the nicotine salt aerosol matched those generated from the Fenton reaction, which are primarily hydroxyl (OH) radicals and other reactive oxygen species (ROS). Although the aerosol mass formation was not significantly different for most of the tested nicotine salts and acid concentrations, notable ROS yields were observed only from BA, CA, and TA under the study conditions. The e-liquids with SLA, LA, LVA, SA, and MA produced less ROS than the 2 wt % freebase nicotine e-liquid, suggesting that organic acids may play dual roles in the production and scavenging of ROS. For BA nicotine salts, it was found that the ROS yield increased with a higher acid concentration (or a lower nicotine to acid ratio). The observation that BA nicotine salts produce the highest ROS yield in aerosol generated from a fourth-generation vape device, which increases with acid concentration, has important implications for ROS-mediated health outcomes that may be relevant to consumers, manufacturers, and regulatory agencies.

Rates of adverse events and related risk factors following e-cigarette use

(2024)

Background

E-cigarettes have emerged as popular products, especially for younger populations. However, concerns regarding health effects exist and there is a notable gap in understanding the prevalence and nature of adverse events. This study aims to examine the rate of adverse events in individuals who use e-cigarettes in a large sample.

Methods

A cross-sectional survey was conducted with a sample of 4695 current and former e-cigarette users with a median age of 34 years. The survey collected data on e-cigarette use, adverse events experienced, product characteristics, related behaviors, sociodemographic factors and presence of medical comorbidities. Statistical analyses were conducted using Pearson's chi-squared tests and logistic regression.

Results

A total of 78.9% of respondents reported experiencing an adverse event within 6 h of using a vaping device, with the most common events being headache, anxiety and coughing. Product characteristics and related behaviors significantly influenced the risk of adverse events. There were also sociodemographic disparities, with Hispanic respondents and those with at least college-level education reporting higher rates of adverse events.

Conclusions

Our study found a high rate of adverse events among e-cigarette users. We identified that certain e-cigarette product characteristics, behaviors and medical comorbidities significantly increased the risk of these events.

Adult Consequences of Repeated Nicotine Vapor Inhalation in Adolescent Rats

(2024)

Introduction

There has been a resurgence in nicotine inhalation in adolescents due to the popularity and availability of Electronic Nicotine Delivery Systems (ENDS). Almost five times as many US high-school seniors inhale nicotine vapor daily compared with those who smoke tobacco. This study was conducted to determine the impact of repeated adolescent vapor inhalation of nicotine on behavior in adulthood.

Methods

Male and female Sprague-Dawley rats were exposed to 30-minute sessions of ENDS vapor inhalation, twice daily, from post-natal day (PND) 31-40. Conditions included vapor from the propylene glycol (PG) vehicle or nicotine (30 mg/mL in the PG). Animals were assessed for effects of nicotine on open field (PND 74-105) and wheel activity (PND 126-180) and for volitional exposure to nicotine vapor (PND 285-395). Plasma nicotine and cotinine were assessed in separate groups of male and female Wistar and Sprague-Dawley rats after a single nicotine inhalation session.

Results

Group mean plasma nicotine ranged from 39 to 59 ng/mL post-session with minimal strain differences detected. Adolescent nicotine exposure enhanced sensitivity to the locomotor stimulating effects of nicotine (0.1-0.8 mg/kg, s.c.) in an open field in female rats, but didn't change the effects of nicotine on wheel activity. Female rats exposed to nicotine (30 mg/mL) vapor as adolescents responded more vigorously than PG-exposed females to nicotine vapor in a fixed ratio 5 challenge.

Conclusions

Repeated adolescent nicotine vapor inhalation leads to enhanced liability for volitional exposure to nicotine vapor in adulthood in female rats, but minimal change in spontaneous locomotor behavior.

Implications

These results show that adolescent vaping of nicotine can lead to lasting sensitization to the effects of nicotine in adulthood, including volitional responding for nicotine vapor. Demonstration of this in a controlled animal model establishes causality in a manner not possible from longitudinal evidence in human populations. These findings further highlight the importance of decreasing adolescent nicotine exposure to e-cigarettes to reduce consumption in adulthood.

Classification of patterns of tobacco and cannabis co-use based on temporal proximity: A qualitative study among young adults

(2024)

Purpose

Co-use of tobacco and cannabis is a common and complex behavior. The lack of harmonized measures of co-use yields confusion and inconsistencies in synthesizing evidence about the health effects of co-use. We aimed to classify co-use patterns based on temporal proximity and describe preferred products and motives for each pattern in order to improve co-use surveillance.

Methods

We conducted semi-structured interviews in a sample of 34 young adults (M_age = 22.8 years, 32.4 % female) during 2017-2019 in California, USA. We employed a qualitative thematic analysis to identify timing, reasons, and contexts for tobacco and cannabis co-use and classify co-use patterns.

Results

Four emergent patterns of co-use with increasing temporal proximity between tobacco use and cannabis use were: Same-month different-day co-use (Pattern 1); Same-day different-occasion co-use (Pattern 2); Same-occasion sequential co-use (Pattern 3); and Same-occasion simultaneous co-use (Pattern 4). Participants used various product combinations within each pattern. Similar motives for all patterns were socialization, product availability, and coping with stress/anxiety. Unique motive for temporally distant patterns (Patterns 1 and 2) was seeking substance-specific effects (e.g., stimulant effect from nicotine, relaxation effects from cannabis), while unique motives for temporally close patterns (Patterns 3 and 4) were seeking combined effects from both substances (e.g., more intense psychoactive effects, mitigating cannabis adverse effects) and behavioral trigger (e.g., cannabis use triggers tobacco use).

Conclusions

Our classification of co-use patterns can facilitate consistency for measuring co-use and assessing its health impacts. Future research should also measure product types and motives for different patterns to inform intervention efforts.