Circadian rhythms in human parotid saliva flow rate and composition

Salivary alpha-amylase stress reactivity in advanced-aged marmosets (Callithrix jacchus): Impacts of cognitive function and oral health status

Salivary alpha-amylase (sAA) is an enzyme found in saliva and is considered a noninvasive biomarker for sympathetic nervous system activity. While a wide range of sAA activity in response to stress has been reported in nonhuman primates, the effects of stress on sAA activity in common marmosets are still unknown. We tested the hypothesis that advanced age and cognitive function may have an impact on stress-related sAA reactivity in marmosets. Thirteen marmosets (nine males and five females) had saliva samples collected during a stressful condition (manual restraint stress) at two different time points, with a 60-min interval. On the next day, the animals underwent the object recognition test (ORT, a type of cognitive test), and then oral examinations. The animals were categorized into two age groups: old (10-13 years), and very old (15-22 years). Irrespective of age, sAA levels showed a significant difference between T1 (mean 2.07 ± 0.86 U/mL) and T2 samples (mean 1.03 ± 0.67 U/mL), with higher values observed at T1 (p < 0.001). The intra-assay coefficients of variation (CV) for low and high sAA concentrations were 10.79% and 8.17%, respectively, while the interassay CVs for low and high sAA concentrations were 6.39% and 4.38%, respectively. Oral health issues were common but did not significantly impact sAA levels. The ORT indicated that the animals could recognize an object placed in the cage 6 h after familiarization. In conclusion, all marmosets showed a higher sAA concentration in the first saliva sample as compared to the second saliva sample collected 1 h later, indicating adaptation to stress. No significant differences in sAA levels were observed between sexes, ORT performance, or oral health. Our results indicate that autonomic responsivity and cognitive (memory) functions were preserved even in very old marmosets.

Aerosol emissions from wind instruments: effects of performer age, sex, sound pressure level, and bell covers

Aerosol emissions from wind instruments are a suspected route of transmission for airborne infectious diseases, such as SARS-CoV-2. We evaluated aerosol number emissions (from 0.25 to 35.15 μm) from 81 volunteer performers of both sexes and varied age (12 to 63 years) while playing wind instruments (bassoon, clarinet, flute, French horn, oboe, piccolo, saxophone, trombone, trumpet, and tuba) or singing. Measured emissions spanned more than two orders of magnitude, ranging in rate from < 8 to 1,815 particles s-1, with brass instruments, on average, producing 191% (95% CI 81-367%) more aerosol than woodwinds. Being male was associated with a 70% increase in emissions (vs. female; 95% CI 9-166%). Each 1 dBA increase in sound pressure level was associated with a 28% increase (95% CI 10-40%) in emissions from brass instruments; sound pressure level was not associated with woodwind emissions. Age was not a significant predictor of emissions. The use of bell covers reduced aerosol emissions from three brass instruments tested (trombone, tuba, and trumpet), with average reductions ranging from 53 to 73%, but not for the two woodwind instruments tested (oboe and clarinet). Results from this work can facilitate infectious disease risk management for the performing arts.

Repeated exposure to epigallocatechin gallate solution or water alters bitterness intensity and salivary protein profile

Polyphenols, bitter and astringent compounds present in many healthy foods, induce varied sensory responses across individuals. These differences in liking and flavor intensity may be attributable, in part, to differences in saliva. In the current study, we tested the effect of repeated consumption of a bitter polyphenol (epigallocatechin gallate, EGCG) solution on perceived bitterness intensity and salivary protein composition. We hypothesized exposure to EGCG would cause an increase in concentrations of salivary proteins that inhibit bitterness of polyphenols. We also hypothesized that participants with higher habitual polyphenol, specifically the flavanols, intake would experience less bitterness from EGCG solutions than those with low habitual intake, and that the high flavanol consumers would be more resistant to salivary alterations. We also tested whether bovine milk casein, a food analog for salivary proteins that may suppress bitterness, would decrease bitterness intensity of the EGCG solution and mitigate effects of the intervention. Participants (N = 37) in our crossover intervention adhered to two-week periods of daily bitter (EGCG) or control (water) solution consumption. Bitterness intensity ratings and citric acid-stimulated saliva were collected at baseline and after each exposure period. Results indicate that bitterness intensity of the EGCG solution decreased after polyphenol (bitter EGCG) exposure compared to control (water) exposure. Casein addition also decreased bitterness intensity of the EGCG solution. While there was not a significant overall main effect of baseline flavanol intake on solution bitterness, there was an interaction between intervention week and baseline flavanol intake. Surprisingly, the higher flavanol intake group rated EGCG solutions as more bitter than the low and medium intake groups. Of proteins relevant to taste perception, several cystatins changed in saliva in response to the intervention. Interestingly, most of these protein alterations occurred more robustly after the control (water) exposure rather than the bitter (EGCG) exposure, suggesting that additional factors not quantified in this work may influence salivary proteins. Thus, we confirm in this study that exposure to bitterness suppresses ratings of bitterness over time, but more work needs to establish the causal factors of how diet influences salivary proteins.

Salivary Protein Roles in Oral Health and as Predictors of Caries Risk

This work describes the current state of research on the potential relationship between protein content in human saliva and dental caries, which remains among the most common oral diseases and causes irreversible damage in the oral cavity. An understanding the whole saliva proteome in the oral cavity could serve as a prerequisite to obtaining insight into the etiology of tooth decay at early stages. To date, however, there is no comprehensive evidence showing that salivary proteins could serve as potential indicators for the early diagnosis of the risk factors causing dental caries. Therefore, proteomics indicates the promising direction of future investigations of such factors, including diagnosis and thus prevention in dental therapy.

Effectiveness of Traditional Chinese Medicine Compound JieDuTongLuoShengJin Granules Treatment in Primary Sjögren's Syndrome: A Randomized, Double-Blind, Placebo-Controlled Clinical Trial

Objective

To evaluate the clinical therapeutic efficacy and safety of JieDuTongLuoShengJin granules + HCQ in patients with pSS.

Methods

40 patients with low-activity-level pSS and without visceral involvement participated in this study and were randomized to receive either JieDuTongLuoShengJin granules with HCQ or placebo with HCQ. Patients and investigators were blinded to treatment allocation. The primary endpoint was week 12 ESSPRI score, while secondary endpoints included ESSDAI, salivary and lacrimal gland function, and some laboratory variables. Safety-related data were also assessed.

Results

Comparing with the placebo group, the treatment group experienced statistically significant improvement in the mean change from baseline for the primary endpoint of ESSPRI score and also in PGA. Moreover, in comparison with baseline values, the treatment group had significantly improved ESSDAI score, unstimulated saliva flow rate, and several laboratory variables. However, upon comparison of the two groups, there were no significant differences for them. The incidence of AEs was 10.0%, one in treatment group and three in placebo group.

Conclusion

Treatment with a combination of JieDuTongLuoShengJin granules with HCQ is effective in improving patients' subjective symptoms and some objective indicators of pSS. These results indicate that JieDuTongLuoShengJin is promising as a safe and effective treatment of pSS.

Chronophysiological features of the normal mineral composition of human saliva

BACKGROUND

The high rate of changes in the composition of saliva can be used for the monitoring of various biorhythms in order to study the physiological characteristics of the human body.

RESEARCH OBJECTIVE

The study of the dynamics of the near-24-h mineral composition of saliva in men and women.

METHODS

The study involved 20 men and 20 women, age 23.1±0.9years. Saliva samples were collected every 3h during the day within 10min. The mineral composition of saliva was defined by the capillary electrophoresis technique. The cross-group differences were evaluated using the non-parametric criterion.

RESULTS

It was shown that the maximum values of the mineralizing capacity fall to 7-8 a.m. and 18-19p.m., which is due to the change in the rate of saliva secretion. The near-24-h dynamics of the saliva pH practically coincides with the dynamics of the Ca/P ratio; there are evident maxima at 9:00 am and 15-18p.m. The values of the Na/K ratio are out of phase with the Ca/P ratio. There is one maximum, corresponding to 3 am in the night, and one minimum at 12-13p.m., which is due to a decreased level of sodium and increased potassium concentration. Statistically valid differences between men and women in pH (p<0.001), concentrations of inorganic phosphorus (p<0.001), as well as Ca/P coefficient (p=0.011) were identified.

CONCLUSION

The dynamics of the studied parameters during 24h is characterized by pronounced intervals.

Psychosocial determinants of diurnal alpha-amylase among healthy Quebec workers

Salivary alpha-amylase (sAA) is a stress-sensitive biomarker the shows promise as an indirect proxy of sympathetic-adrenal-medullary axis activities that are otherwise difficult to discern non-invasively. This comprehensive study investigated diurnal sAA in association with numerous psychosocial characteristics related to mental health, work stress, and non-work stress. Participants included 395 workers (56.1% women, age: M=41.3, SD=10.81) from across 34 distinct workplaces. Diurnal sAA was sampled over two non-consecutive work days at awakening, 30 min after awakening, 14h00, 16h00, and bedtime. Well-validated psychometrics and survey items were used to measure mental health (psychological distress, depression, burnout, work characteristics) (task design, demands, social relations, gratifications), and non-work characteristics (marital/parental status, economic statuses, marital and parental stress, work-family conflicts). Preliminary results revealed that men showed occasionally higher sAA concentrations than women. Multilevel regressions were used to analyze sAA concentrations nested according to levels (i) for each time-point, (ii) between workers, and (iii) across workplaces while covarying for time of awakening, sex, age, cigarette smoking, alcohol consumption, regular physical activity, psychotropic drug use, and body mass index. Main results revealed that psychological demands, support from colleagues, interpersonal conflicts, job recognition and job insecurity appear to be associated with diurnal sAA, while non-work factors did not. Our findings showing a distinct diurnal profile for sAA replicate and expand those of Nater et al. (2007, Psychoneuroendocrinology 32, 392-401), providing further evidence that sAA is associated to subjective psychosocial factors.

Polymorphism in alpha 2A adrenergic receptor gene is associated with sialorrhea in schizophrenia patients on clozapine treatment

OBJECTIVE

Clozapine-induced sialorrhea (CIS) is a common, inconvenient and socially stigmatizing adverse effect. The pathophysiology of CIS may be related to the effect of clozapine on the muscarinic and adrenergic receptors as well as the disruption of the circadian rhythms. The aim of this study was to find out if polymorphisms in muscarinic M1 and M3 receptor genes (CHRM1 and CHRM3), adrenoceptor alpha 2A gene (ADRA2A) or clock circadian regulator gene (CLOCK) are associated with CIS.

METHODS

Two hundred and thirty-seven clozapine-treated Finnish schizophrenia patients were genotyped for CHRM1, CHRM3, CLOCK and ADRA2A polymorphisms, and their salivary dysfunction was assessed with two questions. Twenty-six of these patients had previously been on medication to treat CIS. Comparisons of the genotypes between patients with excessive versus non-excessive salivation were analysed. Genotype distributions between patients and control group and haplotypes were also studied.

RESULTS

CHRM1, CHRM3 and CLOCK polymorphisms and haplotypes were not associated with CIS. ADRA2A (rs1800544) genotype was associated with CIS (p = 0.029). In patients with CIS, CC genotype (n = 103) was more common than in G-allele carriers (n = 79) (p = 0.013, OR 2.13, 95% CI: 1.17-3.88). No differences were found in the distributions of genotypes between patients and controls.

CONCLUSIONS

ADRA2A genotype was associated with CIS.

Salivary enzymes and flow rate: Markers of peptic ulcer

AIM

Peptic ulcers are among the most common and most costly diseases known to human. Its diagnosis in the early stages would have great benefit in treatment of the disease. The aim of this study was to compare alternations of enzymes activity in salivary fluid between patients with peptic ulcer disease and healthy controls.

MATERIALS AND METHODS

Two groups each composed of 26 subjects (13 male and 13 female) patients with peptic and healthy controls entered. Activities of selective salivary enzymes were assayed by a spectrophotometeric method.

RESULTS

The results showed significant increased activity of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) as well as total salivary protein (TSP) concentration in peptic ulcer patients as compared to control group. However, the enzymatic activity of alkaline phosphatase (ALP) also increased in peptic ulcer patients as compared to healthy control, but not statistically significant.

CONCLUSIONS

Based on the obtained results it was concluded that peptic ulcer may be early diagnosed by detecting activity of salivary enzymes. Therefore the saliva can be suggested as a diagnostic fluid.

Semantic conditioning of salivary pH for communication

OBJECTIVES

Semantic conditioning of salivary pH was investigated as a new paradigm for binary communication.

METHODS AND MATERIALS

In a sample of eleven healthy participants, affirmation or negation of presented statements were paired with milk and lemon to condition changes in salivary pH level.

RESULTS

Significant differences between the conditioned reactions were found at the group level. However, the analysis of pH changes on single-subject level revealed significant differences between affirmative and negative responses to the presented statements only for isolated samples in few participants. When classifying a change in pH value of more than .01 as correct response to a statement, only responses to affirmative statements reached mean accuracies of more than 60%.

CONCLUSION

Improvements in the paradigm are necessary before testing it with the critical target population of patients to prove its profit for basic yes/no communication in case no other reliable means of communication could be preserved.

Development of NTCP models for head and neck cancer patients treated with three-dimensional conformal radiotherapy for xerostomia and sticky saliva: the role of dosimetric and clinical factors

PURPOSE

The purpose of this multicentre prospective study was to investigate the significance of the radiation dose in the major and minor salivary glands, and other pre-treatment and treatment factors, with regard to the development of patient-rated xerostomia and sticky saliva among head and neck cancer (HNC) patients treated with primary (chemo-) radiotherapy ((CH)RT).

METHODS AND MATERIALS

The study population was composed of 167 consecutive HNC patients treated with three-dimensional conformal (3D-CRT) (CH) RT. The primary endpoint was moderate to severe xerostomia (XER6m) as assessed by the EORTC QLQ-H&N35 at 6 months after completing (CH)RT. The secondary endpoint was moderate to severe sticky saliva at 6 months (STIC6m). All organs at risk (OARs) potentially involved in salivary function were delineated on planning-CT, including the parotid, submandibular and sublingual glands and the minor glands in the soft palate, cheeks and lips. Patients with moderate to severe xerostomia or sticky saliva at baseline were excluded. The optimum number of variables for a multivariate logistic regression model was determined using a bootstrapping method.

RESULTS

The multivariate analysis showed the mean parotid dose, age and baseline xerostomia (none versus a bit) to be the most important predictors for XER6m. The risk of developing xerostomia increased with age and was higher when minor baseline xerostomia was present in comparison with patients without any xerostomia complaints at baseline. Model performance was good with an area under the curve (AUC) of 0.82. For STIC6m, the mean submandibular dose, age, the mean sublingual dose and baseline sticky saliva (none versus a bit) were most predictive for sticky saliva. The risk of developing STIC6m increased with age and was higher when minor baseline sticky saliva was present in comparison with patients without any sticky saliva complaints at baseline. Model performance was good with an AUC of 0.84.

CONCLUSIONS

Dose distributions in the minor salivary glands in patients receiving 3D-CRT have limited significance with regard to patient-rated symptoms related to salivary dysfunction. Besides the parotid and submandibular glands, only the sublingual glands were significantly associated with sticky saliva. In addition, reliable risk estimation also requires information from other factors such as age and baseline subjective scores. When these selected factors are included in predictive models, instead of only dose volume histogram parameters, model performance can be improved significantly.

Effectiveness of rituximab treatment in primary Sjögren's syndrome: a randomized, double-blind, placebo-controlled trial

OBJECTIVE

To study the efficacy and safety of B cell depletion with rituximab, a chimeric murine/human anti-CD20 monoclonal antibody, in patients with primary Sjögren's syndrome (SS) in a double-blind, randomized, placebo-controlled trial.

METHODS

Patients with active primary SS, as determined by the revised American-European Consensus Group criteria, and a rate of stimulated whole saliva secretion of > or =0.15 ml/minute were treated with either rituximab (1,000 mg) or placebo infusions on days 1 and 15. Patients were assigned randomly to a treatment group in a ratio of 2:1 (rituximab:placebo). Followup was conducted at 5, 12, 24, 36, and 48 weeks. The primary end point was the stimulated whole saliva flow rate, while secondary end points included functional, laboratory, and subjective variables.

RESULTS

Thirty patients with primary SS (29 female) were randomly allocated to a treatment group. The mean +/- SD age of the patients receiving rituximab was 43 +/- 11 years and the disease duration was 63 +/- 50 months, while patients in the placebo group were age 43 +/- 17 years and had a disease duration of 67 +/- 63 months. In the rituximab group, significant improvements, in terms of the mean change from baseline compared with that in the placebo group, were found for the primary end point of the stimulated whole saliva flow rate (P = 0.038 versus placebo) and also for various laboratory parameters (B cell and rheumatoid factor [RF] levels), subjective parameters (Multidimensional Fatigue Inventory [MFI] scores and visual analog scale [VAS] scores for sicca symptoms), and extraglandular manifestations. Moreover, in comparison with baseline values, rituximab treatment significantly improved the stimulated whole saliva flow rate (P = 0.004) and several other variables (e.g., B cell and RF levels, unstimulated whole saliva flow rate, lacrimal gland function on the lissamine green test, MFI scores, Short Form 36 health survey scores, and VAS scores for sicca symptoms). One patient in the rituximab group developed mild serum sickness-like disease.

CONCLUSION

These results indicate that rituximab is an effective and safe treatment strategy for patients with primary SS.

Determinants of salivary alpha-amylase in humans and methodological considerations

Salivary alpha-amylase (sAA) has been proposed as a marker for activity of the sympathetic nervous system (SNS). Recent studies in support of this hypothesis have led to an increased number of researchers integrating amylase measurements into their study designs. Salivary alpha-amylase is produced locally in the salivary glands, controlled by the autonomic nervous system. This entails some methodological consequences and potential pitfalls that might lead to increased error variance and thus prevent successful testing of hypotheses. The goal of this review is to summarize basic and recent findings on methodological issues and potential factors influencing sAA measurement, and to derive a set of recommendations enabling researchers to successfully using sAA in psychoneuroendocrinological experiments.

Effects of oropharyngeal air-pulse stimulation on swallowing in healthy older adults

While previous research has shown that air-pulse stimulation of the oropharynx facilitates saliva swallowing in young adults, the effects of air pulses in older adults have not been examined. Responses to air-pulse stimulation may differ in young and older adults given age-related changes in sensation, swallowing physiology, and swallow-related brain activation. Therefore, this study sought to determine the effects of oropharyngeal air-pulse stimulation on saliva swallowing rates in 18 healthy older adults. Saliva swallowing rates were monitored across six conditions: baseline without mouthpiece, baseline with mouthpiece in situ, unilateral right oropharyngeal stimulation, unilateral left oropharyngeal stimulation, bilateral oropharyngeal stimulation, and sham stimulation. Results indicated that bilateral oropharyngeal air-pulse stimulation was associated with a statistically significant increase in mean saliva swallowing rate compared to baseline without mouthpiece, baseline with mouthpiece in situ, and sham stimulation. In previous studies, young adults reported an irrepressible urge to swallow in response to oropharyngeal air-pulse delivery, but the older adults in the current study did not perceive the air-pulse stimulation as being associated with swallowing or other behaviors. These findings indicate that oropharyngeal air-pulse stimulation facilitates the elicitation of saliva swallowing in older adults.

Saliva as research material: Biochemical, physicochemical and practical aspects

Whole saliva is a complex mixture of proteins and other molecules which originate from several sources. The biochemical and physicochemical properties of saliva contribute to the numerous functions of saliva in, e.g., speech, maintaining oral and general health, and food processing. Interest in saliva has increased in the last few years for its potential to diagnose viral, bacterial and systemic diseases. The use of saliva as research material may pose particular problems due to its inherent variability and instability. This review describes practical aspects of salivary as research material with emphasis on protein biochemistry and physical chemistry.

Determinants of the diurnal course of salivary alpha-amylase

OBJECTIVE

Previous data from our group and others have shown that salivary alpha-amylase activity increases in response to stress. It has been suggested that salivary alpha-amylase may be a marker for adrenergic activity. Less is known about other determinants of salivary alpha-amylase activation. The objective of the current study was to describe the diurnal pattern of salivary amylase and its determinants.

METHODS

Saliva samples were collected immediately after waking-up, 30 and 60 min later, and each full hour between 0900 and 2000 h by 76 healthy volunteers (44 women, 32 men). Compliance was controlled by electronic monitors. In order to control factors which might influence the diurnal profile of salivary alpha-amylase (such as momentary stress, mood, food, or body activity), at each sampling time point the subjects filled out a diary examining the activities they had carried out during the previous hour.

RESULTS

Salivary alpha-amylase activity shows a distinct diurnal profile pattern with a pronounced decrease within 60 min after awakening and a steady increase of activity during the course of the day. Mixed models showed a relative independence of diurnal salivary alpha-amylase from momentary stress and other factors, but significant associations with chronic stress and mood.

CONCLUSIONS

Our results suggest that diurnal profiles of salivary alpha-amylase are relatively robust against momentary influences and therefore may prove useful in the assessment of sympathetic nervous system activity. The findings underscore the need to control for time of day in studies using salivary alpha-amylase as a dependent variable.

T-cell independent production of salivary secretory IgA after hematopoietic stem cell transplantation in children

This study examined the recovery of secretory IgA (S-IgA) in saliva after hematopoietic stem cell transplantation (HSCT) in 35 children and young people between the ages of 3 and 27 years (mean=13.6), and compared this recovery with that of serum immunologic constituents. Reference values for human salivary S-IgA in saliva were obtained from 77 healthy control subjects between the ages of 7 and 25 years (mean=11.4). In the 35 patients, a nadir of secretory IgA concentrations in saliva (S-IgA) was observed between the 3rd and the 4th month, and a return to normal values 1 year after HSCT. Serum IgA concentrations reached their nadir in the 6th month, and normalized in the 18 months after HSCT. The recovery of T-helper cells (CD4+/3+) was also delayed to beyond 18 months. We found a significant correlation between the reconstitution pattern of S-IgA and that of T-helper lymphocytes, but no correlation was found between the post-transplant evolutions of S-IgA and serum IgA, or between S-IgA and T-helper cells. The recovery of S-IgA was more rapid than that of serum IgA and appeared to be T-helper cell independent.

Variability of flow rate when collecting stimulated human parotid saliva

The aim of this study was to estimate the accuracy and reproducibility of citric-acid-stimulated parotid saliva sampling. In healthy volunteers a strong correlation (r2 = 0.79) between flow rates from the left and right parotid gland was observed. In patients with Sjögren's syndrome this correlation (r2 = 0.90) was even stronger. The intraindividual variation in healthy volunteers was 23.3 +/- 5.9%. Increasing the number of collections did not reduce this variation significantly. In head and neck cancer patients, to estimate whether repeated measurements result in more reliable baseline values for use in clinical studies, repeated collections did not result in a significant reduction of intrapatient variation, similar to the results with the healthy volunteers. Thus, notwithstanding the good agreement between left and right flow rates, a high variation in parotid flow rates has to be considered when planning clinical trials evaluating the effects of treatment on salivary gland functioning.

Human salivary gland-specific daily variations in histatin concentrations determined by a novel quantitation technique

Histatins constitute a distinct family of human salivary antimicrobial peptides, of which histatins 1, 3 and 5 are the most abundant. To evaluate salivary gland-specific differences in histatin secretion, we used the recently developed histatin-zinc precipitation method to quantify histatins and to assess daily variations in secretions. Stimulated pure secretions from parotid glands (HPS) and submandibular/sublingual glands (SMSL) were collected from 10 different subjects at four different times of the day (9:35 a.m.; 12:40 p.m.; 2:50 p.m. and 5:00 p.m.). Zinc precipitation and subsequent reversed phase HPLC analysis were performed to determine concentrations of histatins 1, 3 and 5 with reference to purified histatin standards. Both HPS and SMSL secretions displayed daily variations in histatin concentrations. HPS values showed a maximum at mid-day and SMSL samples showed a maximum in the morning. Mean daily histatin concentrations were almost three fold higher in SMSL than in HPS. Mean histatin 1, 3 and 5 concentrations in HPS from 10 subjects ranged from 0.7 to 2.8, 0.6 to 4.3 and 1.0 to 4.3mg%, respectively. The corresponding means in SMSL were 2.8-12.2, 1.5-7.5 and 2.6-9.0mg%, respectively. Remarkably, although histatins constitute only 3-10% of total protein in these secretions, an almost perfect correlation between total protein and total histatin concentrations was observed for both glands. Despite a broad range in histatin concentrations between individuals, this study demonstrated a hitherto unidentified daily variation in histatin concentrations in HPS and SMSL secretions and a differential expression pattern which might have functional implications.

A pH curve of human resting saliva sampled with a small paper slip and its medical application

This paper described physiochemical characteristics of the pH curve of saliva that accompanied escape of CO(2) and that was recorded by a previously reported method. Monthly sample of the resting saliva was collected by a small paper slip from five adults (59.9+/-16.5 years old) over 36 months. The pH curves were examined to represent differences in secretion characteristics among individuals. The following results were obtained: (1) Three variables, pH(1), Delta pH(I), and Delta pH(L), that represent a saliva pH curve indicated secretory characteristics of each individual since the intra-individual variance of them was significantly smaller than the inter-individual variance. (2) These values (mean+/-S.D.) obtained from five adults were 7.03+/-0.54, 0.24+/-0.21, and -0.10+/-0.12, and those obtained from 663 young adults (21.7+/-2.4 years old) were 7.14+/-0.44, 0.26+/-0.23, and -0.08+/-0.13. (3) A characteristic about amplitude of the Delta pH(I) of each individual was maintained over 36 months under the healthy condition. Seasonal variation of the three pH variables and their statistical distribution were also investigated.

The significance of saliva during sleep and the relevance of oromotor movements

Saliva is an essential component of the oroesophageal milieu and allows for normal speech, taste, mastication, food bolus formation and swallowing. Saliva has important functions in protecting the hard and soft tissues of the oral cavity from acids and pathogenic microbes. A large number of people suffer either subjective or objective alterations in quantity and/or quality of their saliva that may be secondary to disease, medications, medical treatments or emotional events. Sleep-related xerostomia is a sensation of dry mouth associated with a report of either mouth and/or throat discomfort that induces awakenings for water intake. The prevalence of self-reported dry mouth complaint during sleep (associated with awakening and water intake) in a Canadian survey was estimated at 23%. The biological significance of decreased saliva during sleep is unknown and it is unclear how the oral cavity compensates for this period of relative dryness. The amount of saliva produced is greatest during the waking hours of the day and diminishes dramatically during sleep and may represent another process in the human body that displays a circadian rhythmicity. Salivary secretion during wakefulness is, in part, associated with oromotor activity involving the masticatory muscles. Rhythmic masticatory muscle activity and swallowing are non-disruptive events that occur during normal sleep. We hypothesize herein that lubrication from saliva is necessary during sleep to protect tissue integrity and health of oroesophageal structures.

Determination of variation of stimulated salivary flow rates

Salivary hypofunction is associated with oral and pharyngeal disorders and requires early diagnosis and intervention. Large variability in salivary flow rates within and between individuals has been reported, which has impaired the establishment of standard values. The objective of this study was to determine variations in stimulated parotid and submandibular flow rates over 6 hours and to define salivary hypofunction. Pooled mean, standard deviation, and coefficient of variation values for four collection time periods were obtained from 36 healthy males and females (18 young, ages 20-38; 18 older, ages 60-77). The results demonstrated 27-44% variation in salivary flow rates over time. Overall, there were no significant age or gender differences in variability between and within salivary flow rates at all collection time periods. The results suggest that a 45% range in salivary flow rates could be considered normal salivary variation, and values below 45% of normal levels could be used to define salivary hypofunction.

Viscosity of whole saliva

This study investigates within-subject variations and associations of salivary viscosities and flow rates in a test panel of healthy adults. After several practice sessions, unstimulated and stimulated whole saliva samples were collected 5 times daily (at 0800, 1100, 1400, 1700, and 2000 h) from 30 university students. There was a significant within-subject variation in viscosity and flow rate of unstimulated saliva (P<0.001). Intra-item correlations were significantly different for salivary flow rates (r= 0.82 for unstimulated, r= 0.88 for stimulated, P< 0.001) and viscosity of unstimulated saliva (r= 0.54, P< 0.05), but viscosity of stimulated saliva was different in this respect. Our results indicate that there is a significant within-subject variation in viscosity of unstimulated saliva.

A computer program for correlating dental plaque pH values, cH+, plaque titration, critical pH, resting pH and the solubility of enamel apatite

A computer program was written in Visual Basic (Microsoft) to calculate (a) the area between a plaque pH curve (as seen after a sucrose rinse) and either a resting pH (around pH 7) or a critical pH value (around 5.5) above at least parts of the pH curve; (b) the solubility of apatite at the pH values in plaque; (c) the area between the plaque pH solubility curve and the apatite solubility at the resting pH/critical pH; (d) the area between plaque cH+ curve and the cH+ value at resting pH/ critical pH; and (e) the area between a plaque pH curve and a cut-off pH value below the curve, e.g. pH 3. It was found that because both the cH+ and the solubility of apatite increased logarithmically with a pH drop, the two latter area functions (d, e) were basically different from those based directly on pH curves. Thus, pH changes around the resting pH value had little effect on areas calculated from concentrations of H+ and solubility. In contrast, a small pH change around pH 4 had a strong impact on both demineralization potential and areas based on cH+. Also, because of the logarithmic nature, demineralization potentials were generally large in comparison to remineralization potentials, a point that has hitherto received little attention.

Development of a recording system for saliva pH with and complete denture by telemetry

A new system for measuring saliva pH by radio telemetry was developed. The system was built into a lower complete denture and could operate for about 19 h. The maximum error in the range pH 5-8 was 0.15 pH, and the correlation when values were compared with those from a glass-electrode pH meter was 0.99. That this system operates successfully was confirmed in a clinical experiment.

Measurement and comparison of the residual saliva on various oral mucosal and dentition surfaces in humans

Using a paper-strip absorption method, the amounts of residual saliva on 20 soft-tissue sites in different regions of the mouths of 20 individuals were surveyed once in the morning after a 12-h fast and again approx. 1-2 h after lunch. After swallowing, saliva at each site was immediately collected on filter-paper strips in a dipstick fashion for 5 s and the volumes were measured electronically with a Periotron micro-moisture meter. A clear pattern of wetness was evident and was almost identical for fasting and postprandial determinations. The hard palate and labial mucosa were covered with the least residual saliva; the floor of the mouth and back of the tongue were the wettest. In the same 20 participants, the amounts of residual saliva on various dentition sites were next measured and, as expected, much higher residual amounts were found in approximal embrasures and occlusal fossae than on adjacent facial or lingual smooth areas. Molars gave higher values than premolar and incisor embrasures. To relate residual saliva dipstick volumes to saliva thickness values, filter-paper strips were applied flat against the same mucosal or dentition surfaces in 10 of the participants, and the volume of the saliva absorbed was measured electronically as before. As the areas of the strips used were known, saliva thicknesses could be calculated. These ranged from 0.01 mm on the hard palate to 0.07 mm on the posterior of the dorsum of the tongue. For the incisor teeth, the calculated residual saliva thickness determined in the same way was about 0.01-0.02 mm. Blotting values plotted against dipstick values for oral sites where blotting could be readily performed showed a linear relation, which could be used as a standard curve to enable the easily done dipstick measurements in microlitres to be converted to saliva thicknesses in millimeters. As blotting could not be done in embrasures and occlusal fossae, this paper-strip absorption method was unsuitable for similar quantification of residual saliva in these sites but was done in another way described elsewhere. Overall, the results indicated that variations in dental morphology, and in the saliva secreted and available to the different oral regions, are the basic factors responsible for the wide variations in residual amounts of saliva seen on the diverse hard- and soft-tissue surfaces of human mouths. Also, finding that the hard palate and inner lips are covered by very thin films of residual saliva suggested that only a small reduction in their quantity would be needed to trigger the dry mouth sensation in hyposalivators.

Human salivary glucose analysis by high-performance ion-exchange chromatography and pulsed amperometric detection

The aim of this project was to develop an analytical procedure with the required level of sensitivity for the determination of glucose concentrations in small volumes of unstimulated fasting whole saliva. The technique involves high-performance ion-exchange chromatography at high pH and pulsed amperometric detection. It has a high level of reproducibility, a sensitivity as low as 0.1 mumol/l and requires only 50 microliters samples (sensitivity = 0.002 pmol). Inhibition of glucose metabolism, by procedures such as collection into 0.1% (w/v) sodium fluoride, was shown to be essential if accurate results are to be obtained. Collection on to ice followed by storage at -20 degrees C was shown to be unsuitable and resulted in glucose loss by degradation. There were inter- and intraindividual variations in the glucose concentration in unstimulated mixed saliva (range; 0.02-0.4 mmol/l). The procedure can be used for the analysis of other salivary carbohydrates and for monitoring the clearance of dietary carbohydrates from the mouth.

Local immunocompetence and salivary cortisol in confinement

The present study describes the effects of a 60-day isolation period on the salivary levels of cortisol and secretory IgA. The study took place in the context of the EXEMSI project in which four volunteers were isolated in a space station-like chamber in the DLR Institute of Aerospace Medicine in order to examine the effects of long term isolation. Inspection of the individual immunoglobulin A secretion rates revealed different patterns of cyclic variation with respect to the weekday-weekend schedule, and different time lags for the adaptation leading to a plateau for this parameter. The salivary cortisol levels showed a circadian rhythm with high concentrations in the early morning (7:30 am) and lower concentrations in the late evening (11:00 pm). Moreover, in all subjects marked increases of salivary cortisol were observed in a 12- to 14-day cycle. In two subjects the marked morning-evening differences were only visible at the weekends. The salivary cortisol and immunoglobulin A levels were determined twice weekly before and after completion of a complex decision-making test. The results reveal a changed responsiveness in all subjects at different times.

Effect of flow rate on tissue plasminogen activator activity in human parotid saliva

Parotid saliva from 10 healthy volunteers was collected at rest and at constant flow rates of 0.25, 0.5 and 1.0 ml/min, and its tissue plasminogen activator (tPA) activity assayed on fibrin plates containing plasminogen. In unstimulated salivas the median tPA activity was 0.26 (range 0.03-2.0) IU/ml. During the first 15 min of stimulation, a continuous decrease in tPA activity was found at the three flow rates; thereafter a steady state was obtained. No significant differences in activity were found between the three rates. The initial decrease was on average 0.15 IU/ml, and the activity during the steady state was 38% of the prestimulatory level. Thus, stimulation with citric acid causes a significant decrease in tPA activity of parotid saliva but this decrease, as well as the reduction rate, appears to be independent of flow rate.

Variation in human salivary pellicle formation on biomaterials during the day

Contact angle measurements were used to study the effects of pellicle formation on polymethyl-methacrylate, dental amalgam and gold. Samples were exposed to saliva in vivo for periods of 5-20 min at three separate occasions during the day. Pellicle drastically increased the wettability of all the materials and effectively sealed off the effect of the original surface activity. Variation in pellicle formation during the day was demonstrated. Pellicles formed at midday showed the least reduction in contact angles compared to those formed during the morning and afternoon. This difference coincided with an increased concentration of inorganic phosphate in saliva at midday. The method enables comparative studies of pellicle formation on hard biosurfaces. The findings indicate differences in the physical behaviour of saliva during the day, and illustrate the importance of making adhesion studies with this variation in mind.

Sialochemistry of whole, parotid, and labial minor gland saliva in patients with oral lichen planus

This study was undertaken to determine whether oral lichen planus in otherwise healthy patients is associated with sialochemical abnormalities. Unstimulated and stimulated whole saliva, stimulated parotid saliva, and stimulated labial minor gland saliva were collected from 25 patients with oral lichen planus and from 25 age- and sex-matched controls. Flow rate and salivary concentrations of immunoglobulins A and G, albumin, amylase, lysozyme, lactoferrin, and total protein were determined by standard analytical techniques. Concentrations of inorganic components including sodium, potassium, calcium, chloride, and phosphate were also measured. No significant differences were found between the lichen planus patients and the controls. These findings do not support an association between oral lichen planus and salivary dysfunction in otherwise healthy patients.

Temporal variations of glandular kallikrein, protein and amylase in mixed human saliva

Variations in the level of glandular kallikrein in human saliva may reflect physiological changes. Diurnal or circadian variations of many salivary components are important in relating changes in such components to oral or systemic conditions especially as most clinical studies are conducted between 0800 and 1700 h. Whole saliva was collected from 14 healthy young subjects at 0800, 1100, 1400 and 1700 h on two Fridays. Samples were centrifuged at 10,000 g for 10 min at 4 degrees C and the supernatant fractions stored at -20 degrees C. The enzymic activity of kallikrein was measured with D-valylleucylarginine-p-nitro-anilide as substrate. The activity of alpha-amylase and the total protein concentration (biuret) were also determined. Results were analysed in a repeated-measures design: there were no significant differences in kallikrein levels either within days or across days. There were significant differences for total protein and alpha-amylase levels within days but, in general, not across days. Minimal individual levels for protein and alpha-amylase were mostly at 0800 h; maxima were generally at 1400 or 1700 h. Kallikrein levels had no marked pattern of maximal or minimal distribution.

Saliva and sweat secretion in man during a one-hour calcium clamp

The effect of a 1-h calcium infusion, directly regulated to obtain and maintain a predetermined blood calcium level ('calcium clamp'), on the composition of parotid saliva, mixed saliva, and sweat was determined in healthy volunteers. An increase in amylase content of the parotid saliva under hypercalcaemic conditions was observed, but the 'calcium clamp' had no effect on flow rate, total and ionized calcium, sodium, potassium, and phosphate levels as well as pH in parotid and mixed saliva. The sweat calcium concentration was negatively correlated with sweat rate, in contrast to sodium and chloride concentrations. Increasing serum calcium levels did not affect ionic composition of the sweat and sweat flow rate.

Influence of atropine on taste-stimulated parotid secretion

Elemental taste qualities as "sour" and "sweet" showed different stimulatory effects on the parotid secretion when given in concentrations with comparable gustatory intensity. Sweet (fructose 10%) exerted an adrenergic-like activity, sour (citric acid 1%) a more parasympathetic-like influence on parotid secretion. The vagal pathway of the gustatory stimuli was further investigated by the simultaneous infusion of atropine sulfate (17 micrograms/kg per 30 min). Atropine reduced the flow rate during sour and sweet stimulation in the range of 500% and 300%. In 60% of the test persons parotid flow rate could not be totally depressed in any of three 10-min sampling fractions by atropine when a sour stimulus was applied; in these subjects protein and amylase concentration increased significantly. Following fructose stimulation the flow rate was totally depressed in all subjects by atropine in the 20- and 30-min sampling fractions. In the first 10-min fraction protein and amylase concentration were not influenced by atropine. The cholinergic pathway seems to be responsible primarily for the flow rate and has further different modulating influence on the stimulatory effect of the individual taste qualities.

The role of glandular kallikrein in the formation of a salivary proline-rich protein A by cleavage of a single bond in salivary protein C

An enzyme was purified from human parotid saliva that can cleave a single arginine-glycine peptide bond between residues 106 and 107 in human salivary proline-rich protein C, hereby giving rise to another proline-rich protein A, which is also found in saliva. The enzyme was purified 2400-fold. It cleaved salivary protein C at the rate of 59 micrograms of protein/h per microgram of enzyme and had amino acid composition, molecular weight and inhibition characteristics similar to those reported for human salivary kallikrein. Confirmation that the enzyme was kallikrein was demonstrated by its kinin-generating ability. Histochemical evidence indicates that a post-synthetic cleavage of protein C by kallikrein would have to take place during passage of saliva through the secretory ducts. In secreted saliva, cleavage of salivary protein C can only be observed after 72 h incubation. In addition, there is no effect of salivary flow rate on the relative amounts of proteins A and C in saliva. On the basis of the experimental observations, it is proposed that in vivo it is unlikely that kallikrein secreted from ductal cells plays a significant role in converting protein C into protein A.

Magnesium concentration in saliva -- an indicator of digitalis toxicity. ?

In a prospective study salivary magnesium was measured by atomic absorption spectrophotometry in 168 patients on chronic digoxin therapy. Magnesium concentration in saliva was correlated with clinical data and plasma digoxin levels. A significant elevation in salivary magnesium concentration was caused by digoxin therapy (0.58 +/- 0.39 mmol/l, n = 93) in comparison to patients with no digitalis treatment (0.17 +/- 0.07 mmol/l, n = 35). Magnesium concentrations in saliva were significantly higher in toxic patients (1.1 +/- 0.68 mmol/l, n = 32) than in nontoxic patients. Possibly toxic patients showed a magnesium level of saliva of 0.63 +/- 0.39 mmol/l (n = 40). In 89% of the intoxicated patients salivary magnesium concentrations were higher than 1.0 mmol/l. The overlap of magnesium between toxic and nontoxic patients was less as compared to calcium and potassium concentrations in saliva. No changes were noted in serum magnesium levels. Magnesium concentration in saliva was influenced by chronic digoxin therapy only. No significant increase of magnesium in saliva was observed within 24 h after i.v. injection of 1.0 mg digoxin in four healthy volunteers. It is concluded that salivary magnesium concentration is a valid method for monitoring digoxin therapy in addition to plasma digoxin levels.

Effects of parathyroid hormone on total protein, calcium magnesium, phosphorus, sodium and potassium concentrations of normal human parotid saliva

The effects of parathyroid hormone (PTH) administered to six young normal adult subjects on protein, calcium, magnesium, phosphorus, sodium and potassium concentrations in parotid saliva have been studied in relation to the salivary flow rate. Stensen's duct was cannulated and excretion patterns of the constituents determined before and after stimulation of saliva production by lemon juice. After a control period (period 1), 50 U of PTH were given i.v. followed by an infusion of 2 U/min for 60-90 min (period 2). In the absence of any detectable changes in plasma, PTH induced a significant rise of salivary protein, calcium, and phosphorus concentrations at rest and following lemon juice stimulation, and of sodium concentration, but only at high flow rates for the latter. PTH did not change magnesium and potassium excretions significantly. Control experiments without PTH were performed on five other subjects. Protein, phosphorus and potassium concentrations did not change significantly between period 1 and period 2. Calcium and sodium excretions were reduced and magnesium excretion increased during period 2. These results provide evidence that PTH acts on the parotid gland by affecting protein secretion and electrolyte transport. Possible mechanisms of these changes are discussed.

[Clinical aspects of non-tumorous diseases of the salivary glands]

The vast field encompassed by the non-tumorous diseases of the salivary glands poses difficult problems for their diagnosis and therapy. In order to facilitate comprehension of the pathological processes and the therapeutical possibilities for their treatment, physiological and biochemical aspects of salivary gland function are presented in the introduction. There are also mentioned in detail most of the diagnostic methods clinically applied today and stress is laid on their respective diagnostic values. In contrast to the opinion of many authors, exploratory excision and puncture are shown to be very important diagnostic tools in salivary gland pathology. The specific application of these methods is often the only means for a reliable diagnosis. The classification of the diseases follows Seifert's (1971) proposal. The chronic diseases of the salivary glands are specifically mentioned with the chronic recurrent and the chronic myoepithelial sialoadenitis taking first place. The sialoses are presented in a larger chapter. An attempt was made to correlate clinical and experimental results, to establish working hypotheses concerning the development of sialoses, to suggest therapeutical possibilities and, last not least, to give an idea of the many clinical and patho-anatomical difficulties to be overcome for a satisfactory understanding of such pathological processes. Finally, various forms of salivary gland fistulas and their treatment are mentioned. The long list of references merely gives an approximation of the abundance of publications dealing with the problems of this field.