Unstimulated Human Saliva Research Articles

Extensive comparison of salivary collection, transportation, preparation, and storage methods: a systematic review

BackgroundHuman saliva as a bodily fluid—similar to blood—is utilized for diagnostic purposes. Unlike blood sampling, collecting saliva is non-invasive, inexpensive, and readily accessible. There are no previously published systematic reviews regarding different collection, transportation, preparation, and storage methods for human saliva.DesignThis study has been prepared and organized according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) 2020 guidelines. This systematic review has been registered at PROSPERO (Registration ID: CRD42023415384). The study question according to the PICO format was as followed: Comparison of the performance (C) of different saliva sampling, handling, transportation, and storage techniques and methods (I) assessed for analyzing stimulated or unstimulated human saliva (P and O). An electronic search was executed in Scopus, Google Scholar, and PubMed.ResultsTwenty-three descriptive human clinical studies published between 1995 and 2022 were included. Eight categories of salivary features and biomarkers were investigated (i.e., salivary flow rate, total saliva quantity, total protein, cortisol, testosterone, DNA quality and quantity, pH and buffering pH). Twenty-two saliva sampling methods/devices were utilized. Passive drooling, Salivette®, and spitting were the most utilized methods. Sampling times with optimum capabilities for cortisol, iodine, and oral cancer metabolites are suggested to be 7:30 AM to 9:00 AM, 10:30 AM to 11:00 AM, and 14:00 PM to 20:00 PM, respectively. There were 6 storage methods. Centrifuging samples and storing them at -70 °C to -80 °C was the most utilized storage method. For DNA quantity and quality, analyzing samples immediately after collection without centrifuging or storage, outperformed centrifuging samples and storing them at -70 °C to -80 °C. Non-coated Salivette® was the most successful method/device for analyzing salivary flow rate.ConclusionIt is highly suggested that scientists take aid from the reported categorized outcomes, and design their study questions based on the current voids for each method/device.

Influence of different sample preparation strategies on hypothesis-driven shotgun proteomic analysis of human saliva

Abstract This research aimed to find an efficient and repeatable bottom-up proteolytic strategy to process the unstimulated human saliva. The focus is on monitoring immune system activation via the cytokine and interleukin signaling pathways. Carbohydrate metabolism is also being studied as a possible trigger of inflammation and joint damage in the context of the diagnostic procedure of temporomandibular joint disorder. The preparation of clean peptide mixtures for liquid chromatography–mass spectrometry analysis was performed considering different aspects of sample preparation: the filter-aided sample preparation (FASP) with different loadings of salivary proteins, the unfractionated saliva, amylase-depleted, and amylase-enriched salivary fractions. To optimize the efficiency of the FASP method, the protocols with the digestion in the presence of 80% acetonitrile and one-step digestion in the presence of 80% acetonitrile were used, omitting protein reduction and alkylation. The digestion procedures were repeated in the standard in-solution mode. Alternatively, the temperature of 24 and 37°C was examined during the trypsin digestion. DyNet analysis of the hierarchical networks of Gene Ontology terms corresponding to each sample preparation method for the bottom-up assay revealed the wide variability in protein properties. The method can easily be tailored to the specific samples and groups of proteins to be examined.

Effect of α-amylase and pH on the rheological properties of thickened liquids containing starch in in vitro conditions relevant to oral processing and swallowing.

The objective of this study was to investigate quantitatively the impact of saliva on the rheological properties of thickened drinks (IDDSI level 3) with different pH. Oral digestion was simulated and followed using a rheometer. An insalivation ratio measured from spitted boli, was used in the in vitro oral digestion experiments, comparing unstimulated human saliva to artificial saliva. The initial viscosity of thickened water samples (pH5.3 and 7.4) was reduced by 80% after only 5s of in vitro oral digestion. A similar viscosity decay was observed with the artificial saliva. This decrease in viscosity was attributed to the breakdown of the starch granule structure by α-amylase and in a lesser extent to a dilution effect. In contrast, the rheological properties of thickened lemon drink (pH=2.7) and thickened orange juice (pH=4.0) were not influenced significantly by human salivary amylase. These results suggest that at these pHs, starch-based thickened drinks can maintain their initial IDDSI level, despite a strong dilution with saliva, which could help in the management of dysphagia. Clinical trials should be performed to confirm this hypothesis. Only human salivary α-amylase should be used to study products between pH3 and 5 to imitate the structural and rheological breakdown happening before swallowing, while α-amylase from Bacillus sp. could also be used outside this range. The method developed in this study can be used to quantify the impact of food oral processing and evaluate rheological properties relevant for swallowing in the presence of saliva.

Effect of gelatinization and swelling degree on the lubrication behavior of starch suspensions

This research aimed to investigate the effect of starch gelatinization and swelling degree on the lubrication properties of starch aqueous suspensions. Three types of maize starch with different amylose content of 70% (HAS), 25% (NS), and <1% (WS) were used to vary the swelling capacities. The granule suspension of NS showed the highest swelling factor (SF) of 26.5, and gave the best lubrication capacity by decreasing friction by 78%. WS was only able to decrease friction by 50% due to a lower swelling capacity. The leached-out amylose increased friction of highly swollen granules (SF = 26.5) but decreased friction of stiff granules (SF = 2.5). Adding unstimulated human saliva to starch suspensions with native and limited swollen granules reduced friction and masked differences in friction coefficients among starch types. Both the salivary layer on the contact surfaces and the salivary proteins in the bulk phase played a role in determining lubrication properties.

Effect of addition of human saliva on steady and viscoelastic rheological properties of some commercial dysphagia-oriented products

Three commercial thickened fluids were rheologically characterized before and after addition of unstimulated human saliva to improve the further development of better products in dysphagia management by taking into account the dynamic process of bolus flow and the effect of saliva. Instant purées (vegetables and beef (VB), vegetables and codfish (VC) and chicken with rice and carrots (CR)) were prepared and mixed with water or unstimulated saliva from five healthy individuals. Steady and dynamic rheological properties were evaluated, and composition of saliva from five donors was determined. Control purées had shear-thinning behaviour and showed a liquid-structured character with different viscoelastic parameters. All the water samples showed significant differences in the steady and viscoelastic parameters although not so notable as those produced by saliva addition. Thereby, addition of saliva produced a remarkable change in: viscosity (at 0.1, 1, 10 and 50 s−1), consistency index (K) and flow behaviour (n), and, in the conformational structure (decrease of maximum stress amplitude (σmax) and maximum complex modulus (G*) and increase in loss factor (tan δ) of all the three purées, especially in CR. VC and CR purées showed an increase in degree of structural deformability (higher γmax). High variability was found in the saliva composition, specifically in α-amylase activity, which might affect the rheological behaviour of these commercial products. Therefore, structural changes produced by saliva addition should take into account to design safer dysphagia products although this inter-individual effect should be studied with a larger number of individuals to obtain more relevant conclusions.

Evaluation of Four Different Denture Cleansers on Tea Stain Removal from Heat Cure Clear Acrylic Resin Specimens—An In Vivo Study

The rough and pitted surfaces seen on acrylic dentures act as niduses for biofilm formation and colonization of microorganisms. Denture cleansers are the most preferred for chemical cleansing, which has been suggested for the disinfection of prostheses. The aim of the study was to evaluate four different denture cleansers on tea stain removal from heat cure clear acrylic resins (DPI heat cure) material. Forty clean acrylic specimens of dimensions 40 mm × 20 mm × 1 mm were fabricated. The samples were then placed in fresh human unstimulated saliva for 2 min to form an initial pellicle layer and facilitate the uptake of stain, and they were washed with water. The samples were divided into 4 batches of 10 each. One-way ANOVA, Tukey’ HSD, and Students’ paired t-test were employed to identify the significant groups at 5% level. The mean value in Batch C, i.e., using Clinsodent powder (0.62 ± 0.32), was significantly higher than the mean values in Batch A, i.e., using Corega Bio Tabs (0.34 ± 0.14), Batch B, i.e., using fitty dent tabs (0.19 ± 0.19), and Batch D, i.e., using Steradent powder (0.25 ± 0.11) (p < 0.05). This study revealed that all the four immersion denture cleansers were effective in removing the tea stains from heat cure acrylic resins. Among the four cleansers, Clinsodent powder removed the tea stains to the greatest extent.

Fully Enzymatic Membraneless Glucose|Oxygen Fuel Cell That Provides 0.275 mA cm(-2) in 5 mM Glucose, Operates in Human Physiological Solutions, and Powers Transmission of Sensing Data.

Coimmobilization of pyranose dehydrogenase as an enzyme catalyst, osmium redox polymers [Os(4,4'-dimethoxy-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) or [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) as mediators, and carbon nanotube conductive scaffolds in films on graphite electrodes provides enzyme electrodes for glucose oxidation. The recombinant enzyme and a deglycosylated form, both expressed in Pichia pastoris, are investigated and compared as biocatalysts for glucose oxidation using flow injection amperometry and voltammetry. In the presence of 5 mM glucose in phosphate-buffered saline (PBS) (50 mM phosphate buffer solution, pH 7.4, with 150 mM NaCl), higher glucose oxidation current densities, 0.41 mA cm(-2), are obtained from enzyme electrodes containing the deglycosylated form of the enzyme. The optimized glucose-oxidizing anode, prepared using deglycosylated enzyme coimmobilized with [Os(4,4'-dimethyl-2,2'-bipyridine)2(poly(vinylimidazole))10Cl](+) and carbon nanotubes, was coupled with an oxygen-reducing bilirubin oxidase on gold nanoparticle dispersed on gold electrode as a biocathode to provide a membraneless fully enzymatic fuel cell. A maximum power density of 275 μW cm(-2) is obtained in 5 mM glucose in PBS, the highest to date under these conditions, providing sufficient power to enable wireless transmission of a signal to a data logger. When tested in whole human blood and unstimulated human saliva maximum power densities of 73 and 6 μW cm(-2) are obtained for the same fuel cell configuration, respectively.

Saliva increases the availability of lipophilic polyphenols as antioxidants and enhances their retention in the oral cavity

ObjectiveLipophilic polyphenols in fruit beverages can avidly bind to surfaces of microorganisms and to blood cells and to impart upon them enhanced oxidant scavenging abilities (OSA). However, since many of the polyphenols are actually not fully soluble in water, they are therefore not available to act as effective antioxidant agents. We hypothesized that whole saliva, proteins such as albumin and mucin, human red blood cells and platelets, may all increase the “solubility” and availability of lipophilic antioxidant polyphenols thus increasing the OSA of whole saliva. DesignThe OSA of whole un-stimulated human saliva, obtained from healthy donors and of combinations among saliva, mucin, blood cells, fruit beverages and reagent polyphenols were quantified by chemiluminescence, DPPH radical and tetrazolium reduction assays. Kinetics of the clearance of polyphenols from saliva after holding in the mouth for 30s of an extract from beverages cinnamon was assayed by the Folin Ciocalteu's and the luminescence assays. ResultsOSA of fruit beverages and of reagent polyphenols were markedly increased by whole saliva, mucin and by red blood cells. Polyphenols associated with a cinnamon extract were retained in the oral cavity for several hours as measured by luminescence and Folin reagent techniques. ConclusionsA new approach to explain the additional role of saliva and salivary proteins and of blood cells as enhancers of OSA of lipophilic polyphenols is presented. This might have a significant importance to assess complex interactions among polyphenols from nutrients, salivary antioxidants, salivary proteins and blood cells extravasated from injure capillaries during infection and inflammation.

High-Resolution &amp;lt;sup&amp;gt;1&amp;lt;/sup&amp;gt;H NMR Investigations of the Oxidative Consumption of Salivary Biomolecules by a Tooth-Whitening Formulation: Relevance to Safety Issues

A multicomponent evaluation of the oxidative consumption of salivary biomolecules by a hydrogen peroxide (H2O2)-containing tooth-whitening formulation has been performed using high-resolution proton (1H) nuclear magnetic resonance (NMR) spectroscopy. Unstimulated human saliva samples (n = 10) were treated with aliquots of supernatants derived from 1) the H2O2-containing whitening gel, 2) the corresponding tooth-whitening accelerant solution containing an amino-alcohol activator, and 3) a combination of these product agents pre-mixed in the recommended manner. 600 MHz 1H NMR spectra acquired on these samples demonstrated that H2O2 present in the whitening gel gave rise to the oxidative decarboxylation of salivary pyruvate (to acetate and CO2), the direct oxidation of trimethylamine and methionine (to trimethylamine-N-oxide and methionine sulphoxide respectively), and the indirect oxidative consumption of lactate and carbohydrates in general. Experiments conducted on a chemical model system confirmed the consumption of pyruvate by added H2O2, and also revealed that this method could be employed for determinations of the H2O2 content of tooth-whitening products. In conclusion, high-resolution 1H NMR analysis provides much valuable molecular information regarding the fate of tooth-whitening oxidants in human saliva, and also permits an assessment of the ability of endogenous antioxidants therein to protect against any soft tissue damage arising from the possible leakage of H2O2 from tooth-whitening application trays.

Complex formation in mixtures of lysozyme-stabilized emulsions and human saliva

In this paper, we studied the interaction between human unstimulated saliva and lysozyme-stabilized oil-in-water emulsions (10 wt/wt% oil phase, 10 mM NaCl, pH 6.7), to reveal the driving force for flocculation of these emulsions. Confocal scanning laser microscopy (CSLM) showed formation of complexes between salivary proteins and lysozyme adsorbed at the oil–water interface and lysozyme in solution as well. To assess the electrostatic nature of the interaction in emulsion/saliva mixtures, laser-diffraction and rheological measurements were conducted in function of the ionic strength by adding NaCl to the mixture in the range between 0 and 168 mM. Increasing the ionic strength reduced the ability of saliva to induce emulsion flocculation as shown by the decreased floc size and the effect on the viscosity. Turbidity experiments with varying pH (3–7) and ionic strength also showed decreased complex formation in mixtures between saliva and lysozyme in solution upon NaCl addition up to 200 mM. Decreasing the pH increased the turbidity, in line with the increase of the positive net charge on the lysozyme molecule. We conclude that electrostatic attraction is the main driving force for complex formation between saliva components and lysozyme adsorbed at the oil droplets and in solution.

Exposure Time of Enamel and Dentine to Saliva for Protection against Erosion: A Study in vitro

Previous research, mainly on enamel, supports a protective role for salivary pellicle against erosion. Pretreatments have tended to be lengthy (24 h or more) and of questionable relevance to the regular intake of acidic food and drink by many individuals. The aim of this study in vitro was to determine the protective effect of salivary pellicle formed on enamel and dentine over time periods up to 4 h. Flattened, polished human enamel and dentine specimens were pretreated with unstimulated human saliva from a single donor for 2 min, 30 min (enamel only), 1, 2, or 4 h. Controls were exposed to water for the same times. Specimens were then exposed to 0.3% citric acid, pH 3.2 for 10 min with stirring. This cycle was carried out 12 times. Tissue loss was measured by profilometry after 3, 6, 9 and 12 cycles. For enamel, statistically significant protection was found at ≧1 h. For dentine, significant protection was achieved at 2 min. Salivary pellicle offered proportionately greater protection to enamel than dentine. Cautiously extrapolating these in vitro data suggests that pellicle should offer erosion protection to individuals who imbibe acidic drinks at frequencies of 1 h or less.

High Resolution 1H NMR investigations of the oxidative consumption of salivary biomolecules by ozone: Relevance to the therapeutic applications of this agent in clinical dentistry

High resolution proton (1H) nuclear magnetic resonance (NMR) spectroscopy was employed to simultaneously evaluate the oxidising actions of ozone (O3) towards a wide range of salivary biomolecules in view of its applications in dental practices, which may serve as a viable and convenient means for the treatment of dental caries. Treatment of supernatants derived from unstimulated human saliva specimens (n=12) with O3 (4.48 mmol) revealed that this reactive oxygen species gave rise to the oxidative consumption of pyruvate (generating acetate and CO2 as products), lactate (to pyruvate and sequentially acetate and CO2), carbohydrates in general (a process generating formate), methionine (giving rise to its corresponding sulphoxide), and urate (to allantoin). Further, minor O3-induced modifications included the oxidation of trimethylamine and 3-D-hydroxybutyrate, the fragmentation of salivary glycosaminoglycans to NMR-detectable saccharide fragments, and the conversion of polyunsaturated fatty acids to their ozonides. Moreover, evidence for the ability of O3 to induce the release of selected low-molecular-mass salivary biomolecules from macromolecular binding-sites was also obtained. Since many of the oxidation products detectable in O3-treated samples are identical to those arising from the attack of *OH radical on biofluid components, it appears that at least some of the modifications observed here are attributable to the latter oxidant (derived from O3*- generated from the single electron reduction of O3).

Concentrations of major elements and mercury in unstimulated human saliva.

The aim of this study was a preliminary assessment of a possible role of human saliva in the diagnosis of some physiological and pathological changes in oral and body functions. Reliable procedures for collection and analysis of samples were established in order to assess total concentrations of Ca, K, Mg, Na, P, and Hg in whole unstimulated saliva. Possible relationships between element concentrations and sex, age, smoking, illness conditions, or side effects resulting from the use of drugs were investigated. The effects of stimulated or unstimulated collection procedures, dental prosthesis, and amalgam fillings were also evaluated. Total concentrations of major cations and Hg in whole saliva from 33 healthy adults living in the Siena district showed a coefficient of variation ranging from 11% (P) to 53% (Na) and average values were in the same range of those previously reported for unstimulated saliva. Healthy males had significantly higher concentrations of K, Na, P, and Na/K, Na/Ca, Na/Mg, and Na/P values than females. Age, smoking, dental prosthesis, and amalgam fillings had no significant effects on the concentrations of major elements. On the contrary, concentrations of Hg were positively correlated to the number of amalgam fillings and increased at a rate of about 1.9 microg/L for each filling. No correlations were found between Hg concentrations and those of major elements. Comparisons with literature data showed a different composition (particularly for Na and Hg concentrations) between unstimulated and stimulated saliva. Samples from patients affected by idiopathic pulmonary fibrosis had significantly higher concentrations of K and the maximum value was measured in a patient affected by acute pulmonary edema. This increase was likely the result of pharmacological treatments with tricyclic antidepressants and/or saline solutions. Data reported in this study, although preliminary, contribute to the assessment of levels of major cations (some of them very little investigated) and Hg in whole unstimulated human saliva and provides consistent support for further research on the possible use of this easy accessible matrix as a diagnostic tool of body function changes.

The propensity of individual saliva to cause extrinsic staining in vitro—a developmental method

Objectives: To detect any differences in the propensity of individual saliva to cause in vitro staining by chlorhexidine and tea. Methods: Unstimulated human saliva was collected on a daily basis and used to coat optically clear Perspex specimens. Specimens were subjected to the original chlorhexidine/tea staining model described by Prayitno and Addy (Journal of Periodontal Research 1979;14:397–402), and cycles repeated until a maximum optical density of two was reached. Results: Stain development increased incrementally with increasing cycles. Differences in chlorhexidine/tea staining between subjects were obvious by cycle 3 where the lowest ‘stainer’ had 56% less stain than the highest ‘stainer’. Highly significant differences between subjects were seen during staining cycles 3–6, but not at cycles 7 and 8. Conclusions: In vitro stain formation using saliva from different individuals occurred at differing rates when all other variables were standardised. The properties of saliva accounting for this are still unknown, and warrant further study.

Characterization of the synthesis and secretion of transforming growth factor-alpha from salivary glands and saliva.

Whole saliva collected from rat, mouse, and human sources was found to contain high concentrations of transforming growth factor-alpha (TGF alpha) when analyzed by RIA. The concentrations of TGF alpha in unstimulated human saliva (age, 30-45 yr; n = 10; 1.5 +/- 3.1 nM) was reduced with age (age, 55-70 yr; n = 10; 0.4 +/- 0.1 nM), but increased in oral pathologies manifested in xerostomia (age, 57-70; n = 6; 0.8 +/- 0.2 nM) and Paget's disease (age, 58-76; n = 8; 2.0 +/- 0.6 nM). Immunohistochemical localization of TGF alpha in the salivary glands of rats and mice revealed specific immunostaining of the granular ductal cells of the parotid and submandibular glands. Reverse transcription followed by polymerase chain reaction amplification of total RNA from the parotid and submandibular glands of rats and mice demonstrated the presence of TGF alpha mRNA, suggesting endogenous synthesis by the salivary glands. Thus, salivary glands appear to be an exocrine source for a second member of the epidermal growth factor-like growth factor family in the oral cavity.

Effect of critical surface tension on retention of oral microorganisms.

The effect of critical surface tension on the initial retention of microorganisms from unstimulated human saliva was tested in a flow cell system. Prior to each experiment the total numbers and the morphotypes of microorganisms present in saliva were recorded. The test surfaces were prepared to display known increasing critical surface tensions, as verified and standardized by contact angle measurements. Surfaces of initially low (20-22 mN/m), medium (35-38 mN/m) and high (greater than 50 mN/m) critical surface tension were exposed to saliva at a flow rate of 1 ml/min. Microbiota and biofilm material associated with the test surface after 15 min of salivary exposure, were then subjected to standard detachment forces, by introducing a cell-free rinsing fluid at two different shear rates. Both the attachment and the detachment phases were executed at room temperature or 37 degrees C. The retained population was counted in three different zones of the test surfaces with a light microscope and statistically tested for correlation to the main variables (critical surface tension, flow rate and temperature) and interactions. Retention success was significantly dependent on the initial critical surface tension and the flow rate. Surfaces of medium critical surface tension, representative of human tooth surfaces and most restorative dental materials, retained the highest numbers of microorganisms in comparison with the other surfaces tested, with no statistically verified selectivity in proportions of retained coccoid and rodshaped microorganisms for any surface. A 30-fold increase of the flow rate resulted in a 70-80% reduction of the retention success, with a higher relative number of cocci present on all the test surfaces. These results demonstrate that initial retention of microorganisms to surfaces is non-specific with regard to morphotypes, but is strongly related both to the mechanical removal forces and the surface energetic state of the solid surface exposed. Retention of microbial populations at interfaces might, therefore, be controllable by advance selection of the critical surface tensions and predicted if shear forces at given sites are known.

In vitro attachment of oral microorganisms to solid surfaces: evaluation of a controlled flow method.

A flow cell method was modified to provide shear-controlled experimental conditions for monitoring initial attachment and detachment of oral microorganisms to solid surfaces. Whole unstimulated human saliva was collected and circulated at a flow rate of 1 ml/min, through a cell composed of two parallel test plates. Infrared-transparent plates of medium surface energy served as test substrata in these initial calibration experiments. The plates presented a similar distribution of polar forces and dispersion forces at the surface as that of human tooth enamel and some restorative dental materials. Internal reflection infrared spectroscopy verified the presence of deposited organic material. After saliva had been circulated through the flow cells for 15 min at 37 degrees C, sterilized distilled water was introduced at the same flow rate and time of exposure to remove unattached microorganisms. Morphologic characterizations and counts of adherent Gram-stainable microorganisms were performed using incident light microscopy. Three different surface zones corresponding to the inlet area, the middle area and the outlet area of the flow cell were analyzed, and compared with enumerations of microorganisms in the whole saliva samples. Numbers of attached microorganisms in the three zones followed predictions from the laminar flow conditions, with a positive correlation shown between total numbers of microorganisms in saliva and total numbers of microorganisms attached. Cocci and rods were the only morphotypes observed on the plates, and no significant difference could be detected between the percentage of cocci and rods attached in the three different zones.(ABSTRACT TRUNCATED AT 250 WORDS)

Haemagglutination inhibition and aggregation of Fusobacterium nucleatum by human salivary mucinous glycoproteins

Whole human unstimulated saliva, parotid saliva and a mucinous fraction resulting from (NH 4) 2SO 4 saturation of saliva showed aggregation of suspensions of Fusobacterium nucleatum and inhibition of its characteristic haemagglutination. This aggregation was inhibited by d-galactose and EDTA but glucose had no effect. Secretory IgA in the mucinous fraction was bound to the bacterial cell aggregates; Sephadex 4B chromatography separated S-IgA from those fractions displaying haemagglutination inhibition and aggregation activity. The active fractions contained high molecular weight mucinous glycoproteins with receptors similar to those for the haemagglutination active moiety on human cells. Salivary mucinous glycoproteins may thus play a role in the colonization of oral fusobacteria.

Gas chromatographic mass spectrometric evaluation of free organic acids in human saliva.

Excellent resolution and subsequent identification of free organic acids extracted from mixed, unstimulated human saliva was obtained by gas chromatography using high resolution open tubular glass capillary columns coupled with mass spectrometry computer instrumentation. In addition to the organic acids, identified as their trimethylsilyl derivaties, the presence of 2,6-di-t-butylcresol--a food preservative--and cholesterol was established by mass spectrometry. The effects of aspirin ingestion as well as diurnal variation were studied to demonstrate the possible clinical significance of this noninvasive approach to metabolic profiling.

METHYL PENTOSES IN HUMAN SALIVA AND DENTAL PLAQUE.

THE average methyl pentose content of unstimulated human saliva supernatants has been determined as being between 50 and 100 µg/ml. depending on the blood-group substance secretor status of the individual1. The methyl pentoses present are fucose and rhamnose. Fucose is present in the blood-group substances secreted in saliva2 and in fractions associated with salivary mucoprotein3, although it is not clear whether or not these two sources are identical. It is seldom found in bacteria. Rhamnose is a constituent of the cell wall of many bacteria4, some of which are found in the mouth. It has not been detected in sterile saliva secretions. Very little is known about the status of methyl pentoses in dental plaque, and it is the purpose of this communication to describe their determination in plaque and their fate in saliva.