BACKGROUND/AIMS: Bitter taste receptors are expressed throughout the digestive tract. Data on animals have suggested these receptors are involved in the gut hormone release, but no data are available in humans. Our aim is to assess whether bitter agonists influence food intake and gut hormone release in healthy subjects. METHODS: Twenty healthy volunteers were enrolled in a double-blind cross-over study. On 2 different days, each subject randomly received an acid-resistant capsule containing either placebo or 18 mg of hydrochloride (HCl) quinine. After 60 minutes, all subjects were allowed to eat an ad libitum meal until satiated. Plasma samples were obtained during the experiment in order to evaluate cholecystokinin (CCK) and ghrelin levels. Each subject was screened to determine phenylthiocarbamide (PTC) tasting status. RESULTS: Calorie intake was significantly lower when subjects received HCl quinine than placebo (514 +/- 248 vs 596 +/- 286 kcal; P = 0.007). Significantly higher CCK DeltaT90 vs T0 and DeltaT90 vs T60 were found when subjects received HCl quinine than placebo (0.70 +/- 0.69 vs 0.10 +/- 0.86 ng/mL, P = 0.026; 0.92 +/- 0.75 vs 0.50 +/- 0.55 ng/mL, P = 0.033, respectively). PTC tasters ingested a significantly lower amount of calories when they received HCl quinine compared to placebo (526 +/- 275 vs 659 +/- 320 kcal; P = 0.005), whereas no significant differences were found for PTC non-tasters (499 +/- 227 vs 519 +/- 231 kcal; P = 0.525). CONCLUSIONS: This study showed that intra-duodenal release of a bitter compound is able to significantly affect calorie intake and CCK release after a standardized meal. Our results suggest that bitter taste receptor signaling may have a crucial role in the control of food intake.
Animals ; Cholecystokinin* ; Cross-Over Studies ; Eating ; Gastrointestinal Tract ; Ghrelin ; Healthy Volunteers ; Humans ; Meals ; Phenylthiourea ; Plasma ; Quinine*

BACKGROUND AND OBJECTIVES: The ability to taste the bitter compounds phenylthiocarbamide is a classic inherited trait in humans. This trait has also been shown to correlate with a number of dietary preferences and thus may have important implications for human health. Recently, the PTC gene that underlies the phenotype was identified. Three single nucleotide polymorphisms in the PTC gene that result in three aminoacid substitutions (A49P, V262A, I296V) demonstrated a strong association with taster status in several studies. The aim of this study was to investigate the relationship between PTC genotype and taster status in normal volunteers. SUBJECTS AND METHOD: Seventy-three healthy normal volunteers were included. Phenylthiocarbamide detection threshold test was performed with successive solutions, which was comprised of a total of 15 grades. PTC gene haplotypes were defined by havingsingle nucleotide polymorphisms at the base pairs, 145,785 and 886, on the PTC gene. RESULTS: Taste sensitivity to phenylthiocarbamide had a bimodal distribution, which givesrise to the practice of dichotomizing subjects into 'tasters' and 'non-tasters'. The percentages of taster and non-taster were 80.8% and 19.2%, respectively. Haplotype analyses of the three single nucleotide polymorphisms inside the PTC gene allowed to identify only two haplotypes that were associated with the non-taster phenotype (100% AVI homozygous) and the taster phenotype (49% PAV homozygous and 51% PAV/AVI heterozygous). CONCLUSION: There was strong concordance between non-tasters defined by phenylthiocarbamide threshold and AVI homozygous by genotype in normal volunteers.
Base Pairing ; Factor IX ; Genotype ; Haplotypes ; Humans ; Phenotype ; Phenylthiourea ; Polymorphism, Single Nucleotide

BACKGROUND AND OBJECTIVES: Phenylthiocarbamide (PTC) and its chemically related compound,6-n-propylthiouracil (PROP), both produce a taste that is extremely bitter to some subjects (tasters) but tasteless or only slightly bitter to others (non-tasters). Earlier studies had used PTC, but most investigators have switched to PROP because of its several advantages. Recently, three single nucleotide polymorphisms in the TAS2R38 gene were identified and several studies have demonstrated a strong association between these genes with taster status. The aim of this study was to investigate the relationship between taste thresholds of PTC and PROP and their correlation with the TAS2R38 genotype. SUBJECTS AND METHOD: Seventy-five healthy normal volunteers were included. Taster status was determined using successive solutions of PTC and PROP, which comprised a total of 15 grades. All participants were genotyped for polymorphism of the TAS2R38 gene that affects taste sensitivity to PTC and PROP. RESULTS: PTC taste thresholds showed 96% correlation with the taste thresholds for PROP. Non-tasters defined by the PTC threshold test were the exactly the same with those identified as AVI (alanine, valine, isoleucine) homozygous, but taster status determined by the PROP threshold test showed 96% correlation with the genotypes. CONCLUSION: The PTC threshold test was more reliable for determining taste blindness than the PROP threshold test.
Ageusia ; Factor IX ; Genotype ; Humans ; Phenylthiourea ; Polymorphism, Single Nucleotide ; Research Personnel ; Taste Threshold ; Valine

BACKGROUND AND OBJECTIVES: The phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP) taste sensitivity varies among individuals. Recently, it is reported that PROP taste responsiveness is associated with carbonic anhydrase 6 (CA6) gene polymorphism. The CA6 gene, a zinc metalloprotein in human saliva, is affected in taste function and might be correlated with gustatory diversity. The aim of this study was to examine whether PTC taste sensitivity and taste disorder is associated with the CA6 gene polymorphism rs2274327 (C/T), rs2274328 (A/C), and rs2274333 (A/G). SUBJECTS AND METHOD: A total of 217 healthy normal subjects were recruited as controls, and 50 taste disorder patients were recruited as experimental group. The polymorphisms of CA6 gene were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis. All statistical analyses were calculated using the statistical package for the social science software. Haplotypes were estimated by Haploveiw and the PHASE programs. RESULTS: The CA6 gene polymorphisms showed association with taste disorder but not with PTC sensitivity (taster/nontaster). The number of control subjects carrying AA genotype of single nucleotide polymorphism rs2274328 (A/C) in the CA6 gene was higher than the number of the subjects with taste disorder (p=0.048). However, there was no association between controls and taste disorder subjects in the haplotype analysis. CONCLUSION: These data suggest that the CA6 gene polymorphism rs2274328 could affect taste function impairment in patients with taste disorder. This observation requires a further functional study of gustin protein to clarify the association of the CA6 gene polymorphisms with the taste disorder and sensitivity.
Carbon ; Carbonic Anhydrases ; Factor IX ; Genes, vif ; Genotype ; Haplotypes ; Humans ; Lifting ; Phenylthiourea ; Polymorphism, Single Nucleotide ; Saliva ; Social Sciences ; Taste Disorders ; Zinc

Ginseng root rot caused by Cylindrocarpon destructans is the most destructive disease of ginseng. Six different fungicides (thiophanate-methyl, benomyl, prochloraz, mancozeb, azoxystrobin, and iprodione) were selected to evaluate the inhibitory effect on the mycelial growth and conidial germination of C. destructans isolates. Benomyl and prochloraz were found to be the most effective fungicides in inhibiting mycelial growth of all tested isolates, showing 64.7% to 100% inhibition at a concentration of 10 µg/mL, whereas thiophanate-methyl was the least effective fungicide, showing less than 50% inhibition even at a higher concentration of 100 µg/mL. The tested fungicides exhibited less than 20% inhibition of conidium germination at concentrations of 0.01, 0.1, and 1 µg/mL. However, the inhibition effect of mancozeb on condium germination of C. destructans was significantly increased to 92% to 99% at a higher concentration of 100 µg/mL, while the others still showed no higher than 30% inhibition.
Benomyl ; Fungi* ; Germination* ; Panax* ; Spores, Fungal ; Thiophanate