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PubMed1975

[Bitter peptides isolated from corn protein zein by hydrolysis with pepsin (author's transl)].

Eight peptides with bitter taste were isolated from a hydrolyzate of the corn protein zein using several chromatographic procedures. The peptides have the following amino acid sequences and taste thresholds (muM/ml): Ala-Ile-Ala (50-100), Ala-Ala-Leu (50-100), Gly-Ala-Leu (50-100), Leu-Glu-Leu (2.5-3.5), Leu-Glu-Leu (8-12), Leu-Val-Leu (1.5-2.5), Leu-Pro-Phe-Asn-Gln-Leu (0.1-0.2), Leu-Pro-Phe-Ser-Gln-Leu (0.1-0.2). The threshold for bitter taste decreases with increasing number of hydrophobic side chains (greater than or equal to C3) in the peptide. It increases in the presence of hydrophilic side chains to their polarity.

Amino Acid Sequence↗
PubMed1993

[A study of hygienic standard for titanium in the source of drinking water].

The smell and taste thresholds of titanium in water were tested. The results indicated that the concentration of smell and taste thresholds for Titanium were 4.329mg/L and 3.332mg/L respectively. The threshold below value of autopurification was 0.1mg/L. The toxicity assessment showed that the acute toxicity of titanium by oral route was of low order according to the toxicity classification. There was no obvious cumulative effect, nor was there mutagenesis demonstrable. Chronic toxicity test of titanium in rats showed that the maximum non-effective concentration was 1.08mg/L. It is suggested that the maximum allowable concentration of titanium in drinking water may be 0.1 mg/L.

Animals↗
PubMed1983

Assessment of the zinc nutritional status of selected elderly subjects.

Elderly participants (with a mean age range of 71 to 75 years) residing in two housing complexes in Tuscaloosa, Alabama, can generally be characterized as predominantly women with a low socioeconomic status living alone. A majority of the participants consumed less than the RDA for food energy. The protein intake was nearly equal to or exceeded the RDA; however, the mean intake of zinc was only half of the RDA. The mean hair zinc concentration of the participants corresponded with the levels reported for this age group by other researchers. Their mean taste thresholds were higher (lower taste acuity) than those reported for young adults. Detection thresholds decreased as the ages of the participants increased. The taste acuity of the participants resembled that of groups of elderly studied by other investigators. A precise definition of low zinc status measurements among the elderly is not available at this time. However, the low hair zinc concentrations and taste acuity, compounded with the low zinc intake, indicate that this population is at risk for zinc deficiency.

Aged↗
PubMed1986

Role of zinc supplementation in type II diabetes mellitus.

Zinc is required for normal immune function and taste acuity and enhances the in vitro effectiveness of insulin. Impaired immune function and taste have been reported in diabetic subjects, and decreased serum zinc levels and hyperzincuria occur in some diabetic subjects and animals. Subjects with type II diabetes were examined to determine whether the similar effects of zinc depletion and diabetes are causally related. Low serum zinc levels were found in 16 of 180 subjects (9 percent). There was no correlation between serum zinc and glycosylated hemoglobin levels. Natural killer cell activity did not differ between diabetic subjects (n = 28) and control subjects (n = 38) and did not correlate with serum zinc levels. T lymphocyte response to phytohemagglutinin was lower in diabetic subjects than in control subjects (70 +/- 10 versus 103 +/- 7 X 10(3) counts per minute) but was not lowest in those with the lowest zinc levels. Taste thresholds for hydrochloric acid, sucrose, sodium chloride, and urea were elevated in diabetic subjects (n = 28) versus control subjects (n = 10), but thresholds did not correlate with glycosylated hemoglobin or serum zinc levels. Zinc supplementation in nine diabetic subjects had no effect on the glycosylated hemoglobin level, natural killer cell activity, or taste thresholds, but it did increase mitogen activity in those with the lowest initial phytohemagglutinin responses. It is concluded that zinc deficiency occurs in a subset of subjects with type II diabetes but is not related to diabetes control and does not explain decreased taste acuity. Zinc deficiency may play a role in abnormal immune function in type II diabetes mellitus.

Adult↗
PubMed1990

Incidence of P.T.C. taste sensitivity and threshold in Kashmiri population.

Taste sensitivity and threshold of Phenylthiourea (PTC) was determined in 800 individuals of Kashmir who form a distinct ethnic group. Correlation, if any, with age, sex, blood group, pH of Saliva, or smoking habits was investigated. The taste sensitivity of P.T.C. increased with advancing age. The percentage of non-tasters was more in blood group 'B' & 'O'. However, no correlation was observed as far as sex, pH of saliva and smoking habits were concerned.

Adolescent↗
PubMed1976

[Relations between structure and bitter taste of amino acids and peptides. II. Peptides and their derivatives (author's transl)].

About 80 peptides and their derivatives were tested for bitter taste. The taste thresholds are in the range of 70-80 muMol/ml (Gly-Val) to 0.01-0.02 muMol/ml (Bacitracin). They are dependent on nature and number of the side chains and on the hydrophobicity of the whole molecule. An estimation of the taste thresholds of all di-and tripeptides with known amino acid composition is possible on the basis of their hydrophobicity. As could be shown recently for bitter amino acids, a polar (electrophilic) and a hydrophobic group are essential requirements for bitter peptides also. This model corresponds to all sensory results, e.g. to the bitter taste of all hydrophobic peptides independent on their sequence and configuration and to the sweet taste of L-aspartyl dipeptide esters.

Amino Acids↗
PubMed1997

Depressive symptoms and alterations in sucrose taste perception: cognitive bias or a true change in sensitivity?

Previous studies have reported elevated taste thresholds in depressed subjects, but those studies did not control for changes in response bias. The current study used signal detection analyses to address this shortcoming. Sucrose detection thresholds were measured (1) in subjects with high and low Hamilton Depression Rating Scale (HAM-D) scores who did not meet standard criteria for current Major Depressive Episode (MDE); and (2) in subjects who did fulfil standard criteria for MDE. Subjects with low HAM-D scores produced significantly more false alarms than the other two groups, but taste sensitivity, as indexed by d', did not vary significantly across groups. These results suggest that changes in response bias underlie previously reported increases in sucrose taste thresholds in depressed subjects.

Adult↗
PubMedDate not supplied

The effects of diabetes and autonomic neuropathy on parotid salivary flow in man.

Stimulated parotid salivary flow studies were performed on 20 non-diabetic subjects and on 30 patients with insulin-dependent diabetes mellitus who had been screened for autonomic neuropathy using tests of cardiovascular reflexes. Electrical gustometry was performed to detect the taste threshold. The stimulated parotid salivary flow rates of diabetics with no autonomic neuropathy or early parasympathetic autonomic dysfunction alone were similar to those of non-diabetic subjects. Diabetic patients with established parasympathetic autonomic neuropathy had significantly higher salivary flow rates as did those with combined sympathetic and parasympathetic neuropathies. Taste thresholds did not correlate either with the duration of the diabetes or with the presence of autonomic neuropathy. The cause of the increased salivary flow associated with diabetic autonomic neuropathy is unclear. It may represent the removal of a neural inhibitory mechanism which modulates salivary flow, or the effects of long-standing diabetes on salivary secretion.

Adult↗
PubMed1984

Taste acuity and zinc status in chronic renal disease.

The malnutrition often associated with progressive renal failure may be related to a progressive deterioration of taste acuity. To determine the relationships between taste acuity, zinc status, and progressive renal failure, 27 subjects were divided into three groups and classified as having mild, moderate, or severe renal failure, with creatinine clearance of 41 to 75, 15 to 40, and 5 to 14 ml/minute, respectively. The subjects were evaluated for recognition taste thresholds for sour and sweet by the Cornsweet method. Serum, urinary, and salivary levels for zinc were determined by atomic absorption techniques. Food diaries were kept for two days; intakes of protein and zinc were calculated from the diaries. There was a significant (p less than .01) inverse relationship between creatinine clearance and recognition taste thresholds for sour and sweet. Serum zinc levels were significantly lower (p less than .01) for subjects with severe renal failure than for subjects with mild renal failure. The subjects who ingested more protein also ingested more zinc.

Adolescent↗
PubMed1977

Phenylthiocarbamide (PTC) taste sensitivity in selected populations of the Isle of Man and Cumbria.

PTC taste thresholds were determined using a modification of the Harris and Kalmus sorting technique for 854 Cumbrian schoolchildren and 699 individuals from the Isle of Man. A non-taster frequency of 19.7 percent was observed in the Cumbrian sample compared with a frequency of 27.8 per cent in that from the Isle of Man. Analysis of taste threshold distributions revealed significant variability, both within and between these two samples. Evidence of significant regional heterogeneity was detected in Cumbria but not in the Isle of Man. Finally, these two series were compared with data from neighbouring regions of the British Isles and Scandinavian populations.

Adolescent↗
PubMed1983

Clinical evaluation of patients referred with symptoms related to oral galvanism.

Sixty-eight consecutive patients (9 males, 59 females) referred for symptoms alleged to be caused by oral galvanism were investigated according to a standardized examination program including clinical examination, epicutaneous patch test with dental materials, haematologic screening, salivary test, calculation of currents created at metallic contacts between restorative materials and testing of electrical taste thresholds. No clinical entity could be identified but recognized clinical conditions that could possibly explain the complaints for which the patients were referred were prevalent. The most common symptoms reported were a smarting sensation in the mouth (71%) and different distant symptoms (47%). As regards oral signs, some of them showed similar prevalences as have been found in a general Swedish population. The main exception was changes at the apex of the tongue - found in 15%. Allergic skin reactions to dental materials were found among 25% of the patients. Mean values of blood and saliva parameters did not differ from what is considered normal. The distribution of currents created by contacting dental metallic restorations showed no deviation from the corresponding currents calculated in a control group. The median value for lowest electrical taste threshold in the group of referred patients was significantly lower than in a control group.

Adolescent↗
PubMed1995

Propylthiouracil tasting: determination of underlying threshold distributions using maximum likelihood.

The ability to taste low concentrations of propylthiouracil (PROP) and related bitter compounds is heritable. The current analysis determines whether the distribution of PROP taste thresholds is consistent with an additive or a dominant mode of Mendelian transmission. To that end, the lowest concentration of PROP detectable was determined for 1015 subjects and models of bi- or tri-modal distributions of PROP taste thresholds were tested. The model with the greatest likelihood had three distributions and followed an additive model of PROP taste sensitivity if the variances associated with the distributions were assumed to be equal. However, if the taste thresholds were transformed to remove skewness, or if the variances were unequal, then three- or two-distribution models were equally likely. Resolution of the mode of inheritance for bitter taste perception awaits additional family studies and the characterization of the molecular basis of taste perception for these bitter compounds.

Adolescent↗
PubMed1995

Taste performance in Sjogren's syndrome.

Sjogren's Syndrome (SS) patients have impaired salivary gland function and an elevated frequency of oral complaints. The taste complaints are thought to be due to sensory deficits that arise in the absence of sufficient saliva to maintain taste receptors. We assessed the subjective complaints, salivary production and taste functioning of SS patients and unaffected individuals. We found the expected decreased salivary gland function and increased frequency of taste complaints. Our taste assessment with weak stimuli confirmed and expanded the previous report of decreased taste threshold sensitivity in SS. However, perception of stronger taste stimuli was not impaired. In contrast with previous reports, patient judgments of intensity were not significantly reduced for any of the four taste qualities. Although the salivary gland function of all patients was markedly impaired relative to that of controls, patients lacking measurable salivary flow were no more likely than patients with residual function to exhibit subjective complaints or taste impairments. Our observations are inconsistent with a simple causal chain running from salivary gland dysfunction to sensory loss to taste complaints.

Adult↗
PubMed1994

[Taste disturbance after tonsillectomy].

There are some patients, though few in number, who complain of taste disturbance after tonsillectomy. Actual measurement of the distance between the lingual branch of the glossopharyngeal nerve, which controls taste in the posterior portion of the tongue, and the lower pole of the palatine tonsil, using a cadaver, showed the distance to be only 2-4 mm, thereby suggesting the danger of direct or indirect disturbance of this nerve by tonsillectomy. Among the 3,583 outpatients complaining of taste disturbance whom we have treated at our taste disorder clinic in the last 15 years, 11 (0.31%) were found to be suffering from taste disorder triggered by tonsillectomy. Among these 11 causes, the causes of taste disturbance have been identified in 8 cases. In three cases, the taste disturbance was caused by direct or indirect damage to the lingual branch of the glossopharyngeal nerve, whereas in another two cases, the disturbance was attributable to medication following tonsillectomy. In the remaining three cases, the diagnosis was a taste disturbance initiated by tonsillectomy but actually caused by a lack of dietary zinc. It is therefore important that patients be informed of the risk of post-operative taste disorder following tonsillectomy, at the time informed consent for tonsillectomy is obtained. It is equally important to measure the taste threshold values for each taste nerve and the serum zinc value as part of the pre-operational examination, and to ask the patients what drugs, if any, they take habitually.

Adult↗
PubMed1998

Threshold distributions of phenylthiocarbamide (PTC) in the Chinese population.

The ability to taste phenylthiocarbamide (PTC) is a well-documented Mendelian trait. Mapping and cloning the gene(s) responsible for the PTC tasting ability would help to delineate the molecular basis for the variations in PTC tasting ability in humans and to shed new light on taste chemosensory functions. In view of the spectacular successes in genome science, the positional cloning strategy seems to be a feasible approach to the isolation of the gene(s) underlying the PTC tasting ability. As a first step toward mapping the gene(s), we collected PTC taste threshold data on 106 individuals, most of them being university students, in Shanghai, China. Using various parametric and nonparametric statistical methods, we have found that the data set is best described by a bimodal distribution. The frequency of PTC nontasters is estimated to be 10%. This is consistent with the view that the PTC nontasting ability follows a recessive mode of inheritance. Several authors had previously reported PTC data on Chinese living outside China. Our data are, to our knowledge, the first ever collected from the Chinese population within China.

Adolescent↗