Taste Exam: A Brief and Validated Test

This protocol measures human taste responses and includes a brief anatomical assessment, a short taste test, and a validation method using the subject's reported sensation and taste receptor genotype.

Transcript

This method can help answer key questions in the medical and sensory field about each person's sense of taste. The main advantage of this technique is its brevity and suitability for biomedical research. The implications of this technique extend towards the diagnosis and treatment of chronic rhino sinusitis because taste receptors are part of the innate immune system.

I will be demonstrating the procedure on our lab member David and Lauren will be making the taste solutions. Begin by instructing the subject to open their mouth. Use a light to illuminate the oral cavity and examine the seven sub-sites of the area.

Here the dorsal tongue is easily visible. Using a tongue depressor to depress the tongue the posterior pharynx becomes visible. Next lateralizing the tongue allows exposure of the left retromolar trigone and the left buccal mucosa.

Here the anterior gingiva and the labial mucosa are visualized. As the subject's tongue is lifted the ventral tongue surface becomes visible. And this allows for examination of the subjects floor of mouth.

The tongue is then lateralized again to examine the right retromolar trigone and the right buccal mucosa. And lastly the hard and soft palate are visualized. Note lesions, abrasions, and masses or signs of inflammation.

Use a light source to visualize the dorsal surface of the tongue and identify the presence or absence of fungiform papillae or smooth surface of the tongue. Finally write down the results of oral cavity examination before proceeding with taste testing. Begin by preparing the taste solutions using a volumetric flask for each to ensure precision of concentrations.

Dissolve samples using ultra pure water. Wrap any light sensitive solutions with foil to reduce exposure to light. Then store the taste solutions at four degrees Celsius.

To identify common errors in solution preparation fill one tasting cup with the old solution and one with the new solution. Taste each solution to verify they are identical in strength. Next, label vial caps with a circular sticker according to the order of presentation and a color code.

In order to match the vial labels with the labels on the taste questionnaire. Package samples by placing them into their respective carriers. Next prepare the taste questionnaire using a category scale for rating taste intensity and a forced choice for identifying the taste quality of each tastant.

Lastly, place circular labels of the appropriate color and number next to the appropriate sample in the taste questionnaire. Provide the subject with the sample box, a bottle of water, an empty cup, pen, and taste questionnaire containing entries for 12 samples. Explain the testing procedure and inform the subject that they will be asked to rate both the intensity and quality of each tastant.

Let them know that they may not experience all qualities. Start the test by asking the subject to rinse their mouth twice with water and spit it out in the cup provided. Have them pour all of sample one into their mouth and hold it there for five seconds before spitting the solution into the cup.

Tell them not to gargle or swallow the solution. Then instruct the subject to circle one of the 13 vertical lines corresponding with the sample's intensity. On a scale of 0 to 12.

From no intensity at all to extremely intense. And choose a single quality to describe the taste. Next ask the subject to rinse their mouth with water twice before proceeding to the next sample.

Observe the subject tasting and rating sample one of water. Should the rating deviate from no intensity at all and no flavor, reiterate the questionnaire instructions before allowing the test to proceed. After all samples have been tasted review the finished questionnaire for completeness.

Finally, score intensity ratings on a scale of 0 to 12 from the vertical lines that the subject circled. And average the two intensity ratings for each tastant for later analysis. Results of the taste test confirm the existence of perceptual taste differences for the bitter compound, Phenylthiocarbamide or PTC among subjects grouped by the TAS2R38 receptor genotype.

Ratings of PTC intensity are significantly different across three genotypes. The motivation behind this study was to try to assess or to develop a rapid point of service exam that we could do in the clinic that would assess the function of this receptor that we believe plays a role in the development of chronic sinusitis. The idea here is could we use this taste test to predict which of our patients are at high risk for developing sinusitis and more importantly, which patients are good surgical candidates for us to do our sinus surgery on, or which ones will do poorly with our sinus surgery.

So we're trying to use this taste test to prognosticate patient's sinal-nasal disease. Once that we went through all of the taste testing we confirmed that by genotyping the patients. And as you can see in figure three for the most part the patient's genotype follows the pattern of their phenotype.

Meaning the more bitter they tasted they tended to be dominant for this receptor. However, there are some outliers. Showing that there are functional homozygotes, PAV/PAVs that said that they didn't taste PTC and on the flip side of that there were some nonfunctional AVI/AVI individuals that tasted PTC with bitterness.

So that means that whatever taste test we do develop if there are patients that are not fulfilling our expectations that we probably wanna confirm the taste test by genotyping them for T2R38. Once mastered the exam and taste test can be performed in under 30 minutes. After watching this video you should have an understanding of how to perform an oral exam, note evidence of disease and perform a brief taste test.

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Taste Exam: A Brief and Validated Test

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