Please select the eligibility criteria that correspond to the clinical trial below.
Title: Vascular Effects of Regular Cigarettes Versus electronIc Cigarette Use
Brief Summary: The purpose of this study is to assess the effects of electronic cigarettes-nicotine and electronic cigarette-nicotine free on endothelial function as compared to traditional cigarettes. Due to ethical reasons, we cannot fully randomise all particpants to the three arms.

Participants who wish to quit smoking will be randomized to

1. Switch to electronic cigarettes containing nicotine plus flavor
2. Switch to electronic cigarettes containing flavor alone Those who do not wish to quit smoking will continue on the Tobacco Cigarette arm Treatment period will be 28 days


Options:
A: Inclusion Criteria:

* Aged 18 years and over
* Currently smoking ≥15 full strength tobacco cigarettes per day for at least 2 years, or roll-up tobacco equivalent (cigar or pipe smokers not included).
* Willing to stop tobacco cigarettes for period of study if required
* Willing not to use electronic cigarettes if required
* Able to give informed consent

Exclusion Criteria:

* Pregnant or lactating.
* Women of childbearing potential who do not abstain from sex or use effective contraception.
* On current prescribed medication for cardiovascular disease.
* History of cardiovascular disease (excluding hypertension), diabetes, active malignance or chronic renal disease.
* Nut allergy
* Participation in another clinical trial (other than observational trials and registries) with an investigational product and/or intervention within 30 days before visit 1.
B: Inclusion Criteria:

* Daily smokers (5≥ cigarettes/day)
* A low socio-economic position (meaning being unemployed or being a recipient of one of the state programs for low income individuals)
* Being available for at least 4 appointments over a 6 month period
* Affiliation to or benefiting from social security or state medical support

Exclusion Criteria:

* Individuals who do not speak French, or who have cognitive impairments making it impossible to understand study information or a condition that makes it impossible for them to give informed consent.
* Major citizens protected by law, adults unable to express their consent and subject to a protective measure (guardianship, curatorship, safeguard of justice)
* Pregnant women or with a pregnancy project, mothers breastfeeding their child(ren).
* Regular smokers who vape daily (at least once a day).
* People who at the time of inclusion are already being managed for smoking cessation (whatever treatment: varenicline, electronic cigarette, NRT, hypnosis, acupuncture, psychotherapy, talk groups, etc.).
* Patients who are already participating in another clinical study (self-reported).
C: Inclusion Criteria:

* The sample, 40 women and 40 men, will be hospitalized patients recruited from Stanford Hospital and Clinics who report smoking at least 10 cigarettes per day prior to hospitalization, have confirmed tobacco use by cotinine testing, and an expected hospitalization of at least 3 days duration from the date of study enrollment. Intention to quit smoking will not be required for study participation.

Exclusion Criteria:

- Study exclusion criteria are: dementia or other brain injury precluding ability to participate; Alzheimer's Disease; Parkinson's Disease; Huntington's Disease; meningitis; seizure disorder of a sustained nature; delirium; brain surgery; drug and/or alcohol dependence; suicidal ideation; end-stage renal disease (i.e., on dialysis); hypertensive crisis; stroke; myocardial infarction (MI) with severe cardiac damage; pregnancy or breastfeeding; non-English speaking; complete homelessness; or currently engaged in tobacco treatment. Study staff will consult with clinical staff prior to approach for study enrollment. In cases of severe renal impairment (estimated creatinine clearance \<30 mL/min), medical staff will consult with participants' physician to assess the appropriateness for study enrollment.
D: Inclusion Criteria:

* Study I - First Phase - No Longer Recruiting

  * Greater than 1 year history of daily smoking
  * 1 month or more of e-cigarette use
  * Able to speak and read English
  * (1) current dual users (of tobacco cigarettes and e-cigarettes) without interest in quitting smoking; (2) current dual users who have attempted, but not quit smoking; (3) current e-cigarette users who have successfully quit smoking; and (4) former dual users who have quit both products.
* Study I - Second Phase - No Longer Recruiting

  * Current dual users (of tobacco cigarettes and e-cigarettes)
  * Smoking at least one cigarette per day over the past year
  * Using e-cigarettes at least once per week over the past month
  * Not currently enrolled in a face-to-face smoking cessation program
  * Able to speak and read English
* Study II - No Longer Recruiting

  * Current dual users (of tobacco cigarettes and e-cigarettes)
  * Smoking at least one cigarette per week over the past year
  * Using e-cigarettes at least once per week over the past month
  * Not currently enrolled in a face-to-face smoking cessation program
  * Able to speak and read English

Answer: A