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

This study has been completed.
Sponsor:
Collaborator:
Information provided by (Responsible Party):
Julie A. Mennella, Monell Chemical Senses Center
ClinicalTrials.gov Identifier:
NCT01399944
First received: July 20, 2011
Last updated: September 15, 2014
Last verified: September 2014
  Purpose

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.


Condition
Healthy

Study Type: Observational
Study Design: Observational Model: Case-Only
Time Perspective: Cross-Sectional
Official Title: The Molecular Basis for a Broad Range of Phenotypes Related to hTAS2R38

Resource links provided by NLM:


Further study details as provided by Monell Chemical Senses Center:

Primary Outcome Measures:
  • Bitter taste thresholds [ Time Frame: 2 days of testing (2 hours each) ] [ Designated as safety issue: No ]
    Thresholds for propylthiouracil (PROP) will be measured using modified Harris-Kalmus recognition thresholds.

  • Taste intensity and hedonic ratings of vegetables [ Time Frame: 3 days of testing (1-2 hours each) ] [ Designated as safety issue: No ]
    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)

  • TAS2R Genotype [ Time Frame: 1 day of testing (1-1.5 hours) ] [ Designated as safety issue: No ]
    Genotype of several TAS2Rs will be determined from DNA extracted from a saliva sample.

  • mRNA expression levels [ Time Frame: 2 days of testing (2 hours each) ] [ Designated as safety issue: No ]
    Expression of taste and related genes will be determined from mRNA extracted from human taste tissue obtained via tongue biopsy.


Secondary Outcome Measures:
  • Dietary habits [ Time Frame: 2 days (2 hours each) ] [ Designated as safety issue: No ]
    Subjects will complete a 24 hour diet recall on 2 days of testing.

  • biometrics [ Time Frame: 1 day (1-1.5 hours) ] [ Designated as safety issue: No ]
    Height, weight, blood pressure and bioimpedance measurements will be taken.


Biospecimen Retention:   Samples With DNA

Saliva and taste tissue will be collected from individuals enrolled in the study.


Enrollment: 70
Study Start Date: July 2011
Study Completion Date: June 2013
Primary Completion Date: June 2013 (Final data collection date for primary outcome measure)
  Eligibility

Ages Eligible for Study:   18 Years to 40 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Sampling Method:   Non-Probability Sample
Study Population

Adults of all races and both genders (N=100) will be involved in the proposed research. Typically, our population of subjects is approximately 45% African American, 45% Caucasian, 6% Hispanic, and 4% Asian. This increased representation of under-represented minorities in our subject populations is reflective of the greater Philadelphia region and has been achieved, in part, through our outreach efforts advertising in local newspapers throughout the city.

Criteria

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.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01399944

Locations
United States, Pennsylvania
Monell Chemical Senses Center
Philadelphia, Pennsylvania, United States, 19104
Sponsors and Collaborators
Monell Chemical Senses Center
Investigators
Principal Investigator: Julie A. Mennella, PhD Monell Chemical Senses Center
  More Information

No publications provided

Responsible Party: Julie A. Mennella, Member, Monell Chemical Senses Center
ClinicalTrials.gov Identifier: NCT01399944     History of Changes
Other Study ID Numbers: 813211, F32DC011975-01A1, R01DC011287-01
Study First Received: July 20, 2011
Last Updated: September 15, 2014
Health Authority: United States: Institutional Review Board

Keywords provided by Monell Chemical Senses Center:
bitter taste
psychophysics
genetics
epigenetics
bitterness sensitivity

ClinicalTrials.gov processed this record on October 16, 2014