Skip to main content
OpenTrials
Completed

NCT Number: NCT01399944

The Molecular Basis for a Broad Range of Phenotypes Related to hTAS2R38

This single-site, within-subject, experimental study is designed to test the hypothesis that individuals express taste receptors differently and have different sensitivities to bitter taste samples, which results from uneven expression. Subjects will include 100 racially and ethnically diverse, healthy adults. All subjects will provide saliva samples for genetic analysis and undergo taste testing with common psychophysical stimuli. From the pool of 100 subjects, 36 subjects from the common heterozygous group (PAV/AVI) and two from each homozygous group (AVI/AVI, nontaster and PAV/PAV, taster) will be invited to return for two additional sessions. During both sessions the investigators will 1) measure bitterness thresholds for PROP, a common psychophysical stimulus; 2) measure bitterness perception of several vegetables; 3) obtain a saliva sample and 4) collect taste papillae. The investigators will then isolate DNA and RNA from the taste papillae and isolate DNA from saliva to evaluate molecular differences over time and between individuals and how it relates to taste psychophysics. All psychophysical and cellular measurements will be done during both sessions so that the investigators can determine how much variation is observed over a one-week time period in both cellular phenotype and psychophysical phenotype.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Healthy

Age range

18 year–40 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Monell Chemical Senses Center

Philadelphia, Pennsylvania, 19104, United States

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Key inclusion criteria include age 18-40 years; English speaking, and good health at the time of study participation.

Exclusion criteria

  • Key exclusion criteria include cigarette smoking, which alters taste perception, oral disease and subjects undergoing Coumadin therapy. Subjects showing signs of oral disease, including tongue lesions or xerostomia will be excluded from tongue biopsy and therefore excluded from the study. Subjects undergoing Coumadin therapy will be excluded from tongue biopsy due to the risk of bleeding, and therefore excluded from the study. Subjects will not be excluded because of economic status, gender, race or ethnicity.

Treatment and study plan

Primary outcomes

  1. Bitter taste thresholds

    Time frame: 2 days of testing (2 hours each)

    Thresholds for propylthiouracil (PROP) will be measured using modified Harris-Kalmus recognition thresholds.

  2. Taste intensity and hedonic ratings of vegetables

    Time frame: 3 days of testing (1-2 hours each)

    Subjects will rate the intensity of five basic taste qualities (bitter, salt, sweet, sour, umami) and the liking of PROP, urea, quinine, caffeine, denatonium solutions and pureed vegetables using the general labelled magnitude scale (gLMS)

  3. TAS2R Genotype

    Time frame: 1 day of testing (1-1.5 hours)

    Genotype of several TAS2Rs will be determined from DNA extracted from a saliva sample.

  4. mRNA expression levels

    Time frame: 2 days of testing (2 hours each)

    Expression of taste and related genes will be determined from mRNA extracted from human taste tissue obtained via tongue biopsy.

Secondary outcomes

  1. Dietary habits

    Time frame: 2 days (2 hours each)

    Subjects will complete a 24 hour diet recall on 2 days of testing.

  2. biometrics

    Time frame: 1 day (1-1.5 hours)

    Height, weight, blood pressure and bioimpedance measurements will be taken.

Sponsors and collaborators

Lead sponsor

Monell Chemical Senses Center

Other

Collaborators

  • National Institute on Deafness and Other Communication Disorders (NIDCD)

Registry information

Important dates

Study start
2011
Primary completion
2013
Study completion
2013
First posted
Jul 22, 2011
Registry last updated
Dec 18, 2017

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.