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Concept: Phenylthiocarbamide

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  Results examining the effects of tasting profile on dietary intake and health outcomes have varied. This study examined the interaction of sweet liker (SL) and supertaster (ST) (bitter taste test through phenylthiocarbamide [PTC]) status with incidence of metabolic syndrome. Participants (n= 196) as part of baseline testing in a behavioral weight loss study completed measures assessing SL and ST status, metabolic syndrome, and dietary intake. SLs were more likely to be African American. More women than men were STs. There was a significant interaction between ST and SL status as associated with metabolic syndrome, after adjustment for demographic characteristics. This interaction was also significantly associated with fiber and caloric beverage intake. Post hoc analyses showed that participants who were only an ST or SL appeared to have a decreased risk of having metabolic syndrome compared with those who have a combination or are neither taster groups (P= 0.047) and that SL + ST consumed less fiber than SL + non-ST (P= 0.04). Assessing genetic differences in taster preferences may be a useful strategy in the development of more tailored approaches to dietary interventions to prevent and treat metabolic syndrome. Practical Application:  Tasting profile, such as sweet liking (SL) or supertaster (ST), may be influenced by genetics, and therefore in turn, may influence dietary intake. The present study found an interaction between ST and SL status with incidence of metabolic syndrome and fiber and caloric beverage intake. Testing people for these tasting profiles may assist with tailoring dietary recommendations, particularly around fiber and caloric beverage intake, and provide a way to modify metabolic syndrome risk.

Concepts: Nutrition, Metabolic syndrome, Taste, Demographics, Preference, Utility, Rock music, Phenylthiocarbamide

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BACKGROUND: We recently demonstrated the bitter taste receptor T2R38 upregulates sinonasal mucosal innate defense in response to gram-negative quorum-sensing molecules through increased nitric oxide production and mucociliary clearance. T2R38 was initially identified in the quest to understand the variability in bitter taste perception to the compound phenylthiocarbamide (PTC) and demonstrated to have polymorphisms generating diplotypes dividing people into PTC supertasters, heterozygotes (with variable PTC detection), and nontasters. We have further demonstrated that sinonasal epithelial cultures derived from supertasters significantly increase innate defenses in response to gram-negative quorum-sensing molecules compared with sinonasal cultures derived from heterozygotes and nontaster individuals. Based on this data, we hypothesize that supertasters are less likely to require sinus surgery compared with heterozygous or nontasters and that supertasters have improved surgical outcomes. METHODS: Banked sinonasal tissue samples from patients who had undergone primary functional endoscopic sinus surgery at the University of Pennsylvania or the Philadelphia Veterans Affairs Medical Center were genotyped for T2R38 and compared to the expected population distribution. Necessity for additional antibiotic therapy following the postoperative healing time frame was evaluated. RESULTS: A total of 28 patients were included in the study. Only 1 supertaster was identified (expected 5.6, p < 0.043). Additionally, 14 heterozygous and 13 nontaster patients were identified. CONCLUSION: This pilot study investigating the genetics of the bitter taste receptor T2R38 in the context of primary sinonasal surgery demonstrates supertaster patients are less likely to need surgical intervention for chronic rhinosinusitis. Additional study is necessary to ascertain postsurgical outcomes.

Concepts: Surgery, Sinusitis, Taste, Nitric oxide, Functional Endoscopic Sinus Surgery, Supertaster, Phenylthiocarbamide, TAS2R38

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It was reported that stimulation of TAS2R38 by a bitter substance, phenylthiocarbamide (PTC), increased P-gp mRNA level and transport activity via release of the gastrointestinal hormone cholecystokinin-8 (CCK-8) at 9 hours. Therefore, we hypothesized that CCK-8 and PTC might also regulate P-gp activity more rapidly via a different mechanism. As a result, we found that the pretreatment of Caco-2 cells with 10 mM PTC significantly decreased the intracellular accumulation of P-gp substrate Rho123 compared with the control after 90 min incubation. Moreover, CCK-8 treatments significantly reduced the accumulation of Rho123 within 30 min, compared with the control. On the other hand, when Caco-2 cells were pretreated with PTC, the efflux ratio of Rho123 was significantly increased compared to control. The efflux ratio of Rho123 in CCK-8 treatment cells was also significantly increased compared to control. Furthermore, CCK-8 increased the phosphorylation of the scaffold proteins ezrin, radixin and moesin (ERM), which regulate translocation of P-gp to the plasma membrane. Therefore, our results indicate that PTC induced release of CCK-8, which in turn induced the phosphorylation of ERM proteins, leading to upregulation of P-gp transport activity via increased membrane localization of P-gp.

Concepts: Protein, Signal transduction, Enzyme, Cell membrane, Cell biology, ERM protein family, Moesin, Phenylthiocarbamide

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The ability to taste bitter thiourea compounds, such as phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), is inherited. Polymorphisms in the bitter-taste receptor TAS2R38 explain the majority of phenotypic variation in the PROP phenotype. It has been hypothesized that the PROP phenotype is a marker for perception of a variety of chemosensory experiences. In this review, we discuss studies that have investigated the relationship between bitter-taste response and dietary behaviors and chronic health in children. Investigators have hypothesized that children who are PROP tasters have lower liking and consumption of bitter foods, such as cruciferous vegetables. Additionally, several studies suggest that children who are unable to taste PROP (i.e., nontasters) like and consume more dietary fat and are prone to obesity. The relationship between the PROP phenotype and obesity is influenced by multiple confounders, including sex, food access, ethnicity, and socioeconomic status. Future studies that adjust for these variables are needed. Expected final online publication date for the Annual Review of Nutrition Volume 36 is July 17, 2016. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.

Concepts: Evolution, Nutrition, Fat, Food, Phenotype, Taste, Vegetables, Phenylthiocarbamide

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The human population displays high variation in taste perception. Differences in individual taste sensitivity may also impact on nutrient intake and overall appetite. A well-characterized example is the variable perception of bitter compounds such as 6-n-propylthiouracil (PROP) and phenylthiocarbamide (PTC), which can be accounted for at the molecular level by polymorphic variants in the specific type 2 taste receptor (TAS2R38). This phenotypic variation has been associated with influencing dietary preference and other behaviors, although the generalization of PROP/PTC taster status as a predictor of sensitivity to other tastes is controversial. Here, we proposed that the taste sensitivities of different bitter compounds would be correlated only when they activate the same bitter taste receptor. Thirty-four volunteers were exposed to 8 bitter compounds that were selected based on their potential to activate overlapping and distinct repertoires of TAS2Rs. Taste intensity ratings were evaluated using the general Labeled Magnitude Scale. Our data demonstrate a strong interaction between the intensity for bitter substances when they activate common TAS2Rs. Consequently, PROP/PTC sensitivity was not a reliable predictor of general bitter sensitivity. In addition, our findings provide a novel framework to predict taste sensitivity based on their specific T2R activation profile.

Concepts: Psychology, Human, Natural selection, Molecular biology, Sense, Taste, Phenylthiocarbamide, TAS2R38

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It has been proposed that taste sensitivity to bitter compounds such as, phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP), represents a genetic marker for an increased vulnerability to depressive illness. Previous explorations of this idea have proven equivocal. This study refines and further explores this idea by focusing specifically on anhedonia (diminished hedonic capacity), a key symptom in some depressive illness, linked also with sensory pleasure. It is hypothesized that diminished PTC taste sensitivity will be associated with more general decrements in hedonic capacity (anhedonia). An opportunity sample of 198 university students were assessed using paper strips impregnated with PTC, the same participants also completed a widely used assessment of hedonic capacity, the Snaith-Hamilton Pleasure Scale (SHAPS). Hedonic capacity scores positively correlated with PTC taste sensitivity; specifically, heightened hedonic capacity was associated with heightened sensitivity to the bitter taste of PTC. Furthermore, modest differences were observed between those least (non-tasters) and most (supertasters) sensitive to PTC, with non-tasters reporting significantly lower hedonic capacity scores than supertasters. PTC taste sensitivity may represent a peripheral risk factor for anhedonia.

Concepts: Genetics, Sense, Taste, Schizophrenia, Dysthymia, Pleasure, Supertaster, Phenylthiocarbamide