Carol M. Christensen

Clinical Criteria for the Diagnosis of Salivary Gland Hypofunction

There is considerable difficulty in the making of initial clinical decisions as to whether a given patient has salivary gland hypofunction, and hence requires additional salivary gland evaluation. This study identified a set of four clinical measures that, together, successfully predicted the presence or absence of salivary gland hypofunction. The four measures were: dryness of lips, dryness of buccal mucosa, absence of saliva produced by gland palpation, and total DMFT; they were derived from discriminant analysis of data collected from 71 individuals with normal and low salivary flow rates. These measures are proposed as criteria for clinical decision-making, as well as for classification of patients in studies of salivary gland dysfunction syndromes. This study also identified unstimulated whole salivary flow rates of 0.12-0.16 mL/ min as the critical range separating individuals with salivary gland hypofunction from those with normal gland function.

Effects of solution viscosity on perceived saltiness and sweetness

Subjects used magnitude estimation to judge the perceived saltiness or sweetness of a series of aqueous solutions containing five suprathreshold concentrations of NaCl or sucrose and thickened with sodium carboxymethylcellulose (CMC). In the first experiment, CMC-H (high viscosity form) was used to thicken a series of sucrose and NaCl solutions to six viscosity levels (1–2,025 centistokes). At the highest viscosity levels, significant decreases occurred in the perceived taste intensity of only the lower concentrations of sucrose and NaCl. A second experiment determined that variations in the quantity of solution sampled from cups did not systematically influence judgments of saltiness when the starting volume was 10 ml. In the third experiment, aqueous solutions containing sucrose or NaCl were thickened with the low (L), medium (M), or high (H) viscosity form of CMC (1–1,296 centistokes). CMC-L-thickened solutions produced little or no suppression of perceived taste intensity, whereas viscous CMC-H solutions produced significant reductions in perceived saltiness and sweetness.

Salivary changes in solution pH: A source of individual differences in sour taste perception

The role of saliva in sour taste perception was investigated in a series of 4 experiments. In one pair of experiments, solution pH was measured before and after acetic, citric or hydrochloric acid solutions were mixed with saliva either normally in the oral cavity or after saliva was directly added to solutions. The results showed that large increases in solution pH occurred over a wide range of acid concentrations and that the changes in pH were related to individual salivary flow rates; greater increases in solution pH occurred among those individuals with higher flow rates. The other pair of experiments measured taste threshold and suprathreshold responses to different volumes of acids. The results demonstrated that individuals with high salivary flow rates were less sensitive to the taste of acids and that large volumes of acid were more easily perceived. The pattern of findings suggest that saliva-induced changes in solution pH are important in sour taste perception.

Human axillary extracts: Analysis of compounds from samples which influence menstrual timing.

Previous studies have shown that menstrual cycle length and fertility are affected by a regular pattern of either: (1) intimate contact with men; or (2) contact with extracts from male axillary secretions; and (3) the axillary extracts of women. Experiments utilizing axillary extracts employed a controlled, double-blind research design using either extract or placebo. The study reported here employed quantitative gas chromatography-mass spectrometry (GC-MS) techniques to determine the concentration of several steroids in the male and female axillary secretion extracts. The steroids examined were: androsterone sulfate, dehydroepiandrosterone sulfate, and the volatile steroid androstenol. The results suggest the following: (1) The concentration of androstenol produced by secretion donors varied during the collection period. Males appear to produce more androstenol at certain times; womens secretions show a menstrual variation in androstenol; the highest concentrations of this compound appear to be produced in the midfollicular phase, prior to ovulation. (2) The concentration of dehydroepiandrosterone sulfate is significantly greater in men than in women. (3) In addition to the steroids, a series of aliphatic acids which range from C2 to C18 in chain length were found. The more volatile members of this series may contribute to the odor of the secretions.

Anticipatory salivary flow to the sight of different foods.

Anticipatory salivary flow was measured to the sight of seven foods that varied in texture, composition and palatability. In one experiment, subjects consumed the test foods that were viewed. This group was tested both during conditions of hunger and satiation. In a second experiment, subjects were instructed that they would not consume the foods that were viewed. Salivary responses were not related to the anticipated palability of the test foods but rather appeared to be related to the physical and chemical properties of the foods. Pizza, chocolate cake and gelatin were rated as highly palatable, but significant salivary increases occurred only with pizza. Of all the test foods, the greatest salivary flow increases were observed to the sight of lemon slices and pizza, and both foods contain sour or pungent ingredients. Hunger state and the expectation of consuming the test foods did not systematically affect the pattern or magnitude of salivary responses.

Effects of taste quality and intensity on oral perception of viscosity

Oral assessments of viscosity were obtained with the method of magnitude estimation. Subjects judged the viscosity of a series of aqueous solutions thickened to one of six viscosity levels (1–2025 centistokes) with a food-grade gum, sodium carboxymethylcellulose. The solutions contained one of several concentrations of caffeine, citric acid, sodium chloride, or sucrose. The presence of taste substances significantly altered the perception of solution viscosity for only the thickest solutions. Increasing concentrations of citric acid and sodium chloride produced progressive decreases in perceived viscosity, and increasing sucrose concentrations produced small increases in perceived viscosity. Caffeine did not affect judgments of solution viscosity. The most likely explanation for these findings is that subjects detected differences in the Newtonian behavior of the thickened solutions, differences that were produced by the addition of taste substances.

Preference of rats for food flavors and texture in nutritionally controlled semi-purified diets

Preference for nutritionally controlled, semi-purified diets modified by the addition of potent food flavors was determined for Sprague Dawley rats using two-choice diet preference tests. Intake of each food cup was monitored after 1 hr and for each 24 hr period thereafter up to 5 days. Preference was also determined for the flavored diets prepared in three forms differing in texture: powdered, and pellets of two sizes. Rats easily detected minor amounts of the food flavors, and the tests provided a catalog of 12 preferred flavors. Exposure time to the diets altered preference for a minority of flavors; diets initially avoided in the first hour test were likely to become less aversive upon continued exposure. Whether or not a specific flavored diet was preferred, total food intake was not affected during the 5 day period monitored. Rats displayed strong preference for diets of a pelleted texture compared to the same diets in a powdered form.

Bacterial agglutinin activity in the saliva of human identical and fraternal twins

The major factor in human saliva responsible for the specific aggregation of oral streptococci is a high molecular-weight glycoprotein (agglutinin). To determine if the level of this glycoprotein in whole and parotid saliva was genetically determined, agglutinin activity for Streptococcus sanguis and Streptococcus mutans in saliva obtained from identical and fraternal twins was compared. Evidence for the heritability of agglutinin activity and also parotid flow rate and total protein was obtained. There was no evidence for a significant genetic contribution to salivary sodium concentration.

The influence of moderate reduction in dietary sodium on human salivary sodium concentration

Twenty-four healthy subjects were placed for 12-13 weeks on diets that reduced average sodium intake from 145 to 74 m-equiv. Na+/day as determined by multiple 24-h urine collections before and during the diet. Whole-mouth resting and stimulated saliva was collected and analysed for flow rate and sodium concentration several times before and during the low-sodium period. Sodium restriction did not influence salivary flow rates but salivary sodium levels fell 25 per cent for resting and 17 per cent for stimulated saliva. Thus moderate reductions in sodium intake are accompanied by significantly lower salivary sodium levels.