Methodological considerations in the use of salivary α-amylase as a stress marker in field research

Effect of 1% H2O2 on Three Salivary Stress Biomarkers, Cortisol, Alpha-Amylase, and sIgA

BACKGROUND

Due to the COVID-19 pandemic, several associations worldwide have been recommending the use of 1% hydrogen peroxide solution as a preprocedural mouth rinse before dental treatments to reduce viral load in saliva. This protocol is also employed in stress studies, especially in the context of dental treatment that uses salivary biomarkers as an indicator. However, the effect of 1% hydrogen peroxide as mouth rinse on salivary biomarkers remains unclear.

OBJECTIVE

This study aims to investigate the effects of 1% hydrogen peroxide solution as a preprocedural mouth rinse on 3 salivary stress biomarkers-salivary cortisol, salivary secretory IgA, and salivary α-amylase-both on chemical influence and mechanical irrigation.

MATERIALS AND METHODS

Ninety healthy participants with confirmed negative Reverse Transcription Polymerase Chain Reaction results for COVID-19 at most 2 days prior to the experiment were included in this study. All participants were randomly allocated into 3 groups: experimental (1% hydrogen peroxide solution), positive control (distilled water), and negative control (no mouth rinse). Saliva samples were collected before and after mouth rinsing with the respective solutions. Salivary biomarkers were analysed using specific enzyme-linked immunosorbent assay kits.

RESULTS

Salivary cortisol and salivary α-amylase did not significantly differ before and after rinsing, whilst salivary sIgA levels decreased in all 3 groups. Nonetheless, there were no significant differences in the changes of these biomarkers across the 3 groups.

CONCLUSIONS

This study shows that using 1% hydrogen peroxide solution as a preprocedural mouth rinse for universal precaution does not alter the levels of these 3 salivary biomarkers.

Stability and durability of salivary alpha-amylase across different storage conditions

Data collection in remote and field settings gains importance and popularity in stress research. Accordingly, existing stress induction paradigms have been successfully adapted to remote and field settings. However, guidelines for the comprehensive assessment of biomarkers such as salivary alpha-amylase (sAA) have yet to be sufficiently established for such contexts. In remote and field settings, swift freezing of saliva samples is not always possible, and samples must be returned to the laboratory for further processing. The current study investigated the robustness of sAA activity against external factors that may affect measurements obtained from saliva samples collected in field and remote settings. We compared sAA activity of samples that were stored in different vials (Salivettes® and Eppendorf® vials) and that were exposed to (1) up to three cycles of freezing and thawing, (2) different temperatures (4 °C, 20 °C, 30 °C, and 40 °C) for 3, 7, 14, or 28 days, or that were (3) sent via postal delivery. Results indicate sAA activity to be susceptible across different temperatures, different time intervals, and different vials. As a systematic pattern, sAA activity seems to decrease in treated samples with this effect being potentiated by more extreme conditions such as higher temperatures and longer time intervals. To conclude, sAA data collected in remote or field settings could be affected systematically by various external variables. Future studies collecting sAA should take factors influencing the durability and stability of sAA into account to ensure reliable and valid measurements of salivary data.

Evaluation of fatigue in young female adults due to repeated exposure to heat in summer and cold in winter

PURPOSE

The magnitude of fatigue (MF) from psychological and physiological responses during repeated exposure to heat in summer and during repeated exposure to cold in winter was evaluated to test two hypotheses on fatigue models. The first hypothesis is that exposure time (ET, min) would be a factor determining the MF and the second hypothesis is that the same fatigue models as a function of the number of exposure repetitions (NR) could be applied to both repeated exposure to heat in summer and cold in winter.

METHODS

In summer, eight young adult female subjects with clothing insulation (Icl, clo) of 0.3 clo first stayed in the control room at 26 ℃ for 15 min, moved to the main testing room at 30 ℃ for 25 min, 33 °C for 15 min, or 36 ℃ for 10 min, and then returned to the control room. The product of air temperature difference (ΔTa, ℃) and ET was designed to be almost equal among these latter three conditions. The exposure was repeated five times. In winter, the same female subjects with Icl of 0.84 clo first stayed in the control room at 24 ℃ for 15 min, moved to the main testing room at 18 ℃ for 30 min, 15 ℃ for 20 min, or 12 ℃ for 15 min, and then returned to the control room. Again, the product of ΔTa and ET was designed to be equal among these latter three conditions. The exposure was repeated four times. The scores of subjective fatigue feeling (SFF) and salivary amylase value (SAV) were recorded when the subjects returned to the control room. Tympanic temperature, skin temperatures and local sweat rates (Sw, mg/cm2/min) at chest, forearm, front thigh, and front shin, and ECG were continuously monitored, except for Sw in the winter experiment.

RESULTS

In the summer experiment, the SFF showed a threshold value at ΔTa = 4 ℃ but continuously increased with NR at ΔTa = 7 ℃ and 10 ℃. It was not correlated with ECG variables, but was positively correlated with SAV (R2 = 0.50) and the mean Sw (R2 = 0.76) at ΔTa = 7 ℃ and 10 ℃. In the winter experiment, the SFF showed a threshold value at ΔTa =  - 6 ℃ but continuously increased with NR at ΔTa =  - 9 ℃ and - 12 ℃. It was correlated with SAV at ΔTa =  - 9 ℃ (R2 = 0.77) and score of LF: HF ratio at ΔTa =  - 6 ℃ and - 9 ℃ (R2 = 0.49).

CONCLUSION

It was confirmed that ET may be related to the MF and that different fatigue models may be applied dependent on ΔTa during repeated exposure to heat in summer and during repeated exposure to cold in winter. Thus, the two hypotheses were verified.

Clinical correlation of salivary alpha-amylase levels with pain intensity in patients undergoing emergency endodontic treatment

BACKGROUND

Pain is usually subjective and thus it is challenging to describe its characteristics such as nature, intensity, and origin. Non-invasive methods such as assessing salivary alpha-amylase (SAA) may aid the practitioner to evaluate the pain intensity. Hence, the current study aimed to correlate the levels of SAA with the pain intensity in patients presenting with varied endodontic pain levels.

METHODS

Sixty patients who presented with varied intensities of endodontic pain were selected for the present study out of which seven patients were excluded/dropped, leaving a total sample of fifty-five patients for assessment. Mandibular molar with symptomatic irreversible pulpitis without periapical pathology were included in the study. A 5ml of un-stimulated was obtained from the patients, following which the local anesthesia was administered. Root canal treatment was then performed and the pain scores at pre-operative and post-operative were recorded. Additionally, salivary samples were collected after emergency endodontic treatment and sent for sialochemical analysis. IBM.SPSS statistics software 23.0 was employed to assess the obtained data.

RESULTS

A statistically significant drop in the pain score (P < 0.001) and SAA levels (P < 0.001) were observed post-operatively in the contract to pre-operative state. A strong positive correlation was reported between SAA levels and pain scores in patients undergoing emergency endodontic treatment at both time intervals namely pre-operative (P < 0.001) and post-operative (P < 0.001).

CONCLUSION

The results of this preliminary showed a strong association between the pain score and SAA levels in patients undergoing an emergency endodontic treatment.

Applying minimally invasive biomarkers of chronic stress across complex ecological contexts

Chronic stress is both theoretically and methodologically challenging to operationalize through biomarkers. Yet minimally invasive, field-friendly biomarkers of chronic stress are valuable in research linking biology and culture, seeking to understand differential patterns of human development across ecological contexts, and exploring the evolution of human sociality. For human biologists, a central question in measurement and interpretation of biomarkers is how stress-responsive physiological systems are regulated across diverse human ecologies. This article aims to describe a conditional toolkit for human biologists interested in the study of chronic stress, highlighting a mix of longstanding and novel biomarkers, with special focus on hair/fingernail cortisol, latent herpesvirus antibodies, allostatic load indices, and serial/ambulatory data collection approaches. Future trends in chronic stress biomarker research, including epigenetic approaches, are briefly considered. This overview considers: (1) challenges in separating a distinctly psychosocial dimension of chronic stress from adversity more broadly; (2) essential characteristics of human ecology that shape interpretation; (3) retrospective vs. longitudinal sampling; (4) the role of age, developmental effects, and local biologies; (5) different timescales of chronicity; and (6) the role of culture.

Changes in salivary analytes in cows due to the in vitro presence of feed

BACKGROUND

The effect in a sialochemistry profile of the presence of usually available feed in dairy cows was evaluated by an in vitro experiment. For this purpose, a pooled clean saliva from five healthy dairy cows was incubated five times with a standard feed based on a total mixed ration (F), wheat hay (H), and grass (G). The salivary panel was integrated by biomarkers of stress (cortisol -sCor-, salivary alpha-amylase -sAA-, butyrylcholinesterase -BChE-, total esterase -TEA-, and lipase -Lip-), immunity (adenosine deaminase -ADA-), oxidative status (Trolox equivalent antioxidant capacity -TEAC-, the ferric reducing ability of saliva -FRAS-, the cupric reducing antioxidant capacity -CUPRAC-, uric acid, and advanced oxidation protein products -AOPP-), and enzymes, proteins, and minerals of general metabolism and markers of liver, muscle, and renal damage (aspartate aminotransferase -AST-, alanine aminotransferase -ALP-, γ-glutamyl transferase -gGT-, lactate dehydrogenase -LDH-, creatine kinase -CK-, creatinine, urea, triglycerides, glucose, lactate, total protein, phosphorus, and total calcium).

RESULTS

Most of the evaluated analytes showed a coefficient of variations (CV) higher than 15% and/or significant changes compared with the clean saliva when feed was present. Some analytes, such as the oxidative status biomarkers (CV > 80%), AST (CV > 60%), or glucose (CV > 100%), showed significant changes with all the feed types tested. Others showed significant differences only with certain types of feed, such as LDH with F (CV > 60%) or triglycerides with F (CV > 100%) and H (CV > 95%). However, sCor or gGT remained unchanged (CV < 15%, P > 0.05) in all the treatments.

CONCLUSIONS

The presence of feed can produce changes in most of the analytes measured in cows' saliva, being of high importance to consider this factor when saliva is used as a sample to avoid errors in the interpretation of the results.

Changes Occurring on the Activity of Salivary Alpha-Amylase Proteoforms in Two Naturalistic Situations Using a Spectrophotometric Assay

Simple Summary

Salivary alpha-amylase (sAA) is considered a biomarker of acute stress since this enzyme is released in saliva after autonomic nervous system activation, in response to psychological or physical stress situations. This enzyme has different isoforms that could be differentially expressed depending on the stressful situation. The aims of the present research were (1) to develop and validate an easy and fast method to estimate the activity of the major sAA proteoforms (both non-glycosylated and glycosylated proteoforms) in saliva samples, and (2) to evaluate the possible changes occurring in the activity of both proteoforms when measured by this method in two different stress models (physical effort and psychological challenge). This new method was precise and, when applied to the different stress models, allowed to detect changes of different magnitudes in both proteoforms. Therefore, this research opens a new field for the evaluation of isoforms of sAA as potential biomarkers of stress.

Abstract

This study aimed to evaluate the changes in the activity of total salivary alpha-amylase (TsAA) and both the non-glycosylated and glycosylated salivary alpha-amylase proteoforms (NGsAA and GsAA, respectively) in physical and psychological stress models, estimated using a simple and easily set-up method. The method used was a spectrophotometric assay with 2-chloro-4-nitrophenyl-α-D-maltotriose (CNPG3) as a substrate, incubated with Concanavalin A (ConA) to remove most of the glycosylated protein from the sample. This method allowed the measurement of TsAA and estimation of NGsAA and GsAA activities with imprecision lower than 10%. When this method was applied to two different stress models, differences in the responses of the proteoforms were observed, with the NGsAA activity showing changes of higher magnitude after stress induction than the GsAA activity, and the highest correlation with the State–Trait Anxiety Inventory Scale in the Trier Social Stress Test (TSST). In conclusion, the activity of the two main sAA proteoforms can be easily estimated in saliva, and their measurement can provide additional information on TsAA activity in physical or psychological stress situations.

Relationship between Parafunctional Habits and Salivary Biomarkers

Objectives:

Parafunctional habits, as one of the etiological factors of temporomandibular disorders (TMD), are an individual’s response to increased stress. During stress and depression, biomarkers such as cortisol and salivary alpha-amylase (SAA) are secreted in the saliva. The present study aimed to investigate whether there is a correlation between salivary stress biomarkers and parafunctional habits.

Materials and Methods:

Thirty-two cases, from May to September 2015, were selected based on two standard stress questionnaires, namely the depression anxiety stress Scale-21 (DASS-21) and the Beck Anxiety Inventory (BAI). Saliva samples were collected to examine the level of unstimulated salivary cortisol and SAA. The significance of the results was assessed via student’s t-test and Mann-Whitney test (α=0.05).

Results:

The mean concentrations of cortisol and SAA in unstimulated saliva were significantly higher in the case group than in the control group (P=0.01 and 0.44, respectively). The mean scores of anxiety, stress, and depression were significantly higher in the case group than in the control group (P<0.05).

Conclusion:

It seems that the levels of salivary cortisol and SAA, as well as stress, anxiety, and depression scores, are higher in patients with parafunctional habits.

Analytical Strategies in Lipidomics for Discovery of Functional Biomarkers from Human Saliva

Human saliva is increasingly being used and validated as a biofluid for diagnosing, monitoring systemic disease status, and predicting disease progression. The discovery of biomarkers in saliva biofluid offers unique opportunities to bypass the invasive procedure of blood sampling by using oral fluids to evaluate the health condition of a patient. Saliva biofluid is clinically relevant since its components can be found in plasma. As salivary lipids are among the most essential cellular components of human saliva, there is great potential for their use as biomarkers. Lipid composition in cells and tissues change in response to physiological changes and normal tissues have a different lipid composition than tissues affected by diseases. Lipid imbalance is closely associated with a number of human lifestyle-related diseases, such as atherosclerosis, diabetes, metabolic syndromes, systemic cancers, neurodegenerative diseases, and infectious diseases. Thus, identification of lipidomic biomarkers or key lipids in different diseases can be used to diagnose diseases and disease state and evaluate response to treatments. However, further research is needed to determine if saliva can be used as a surrogate to serum lipid profiles, given that highly sensitive methods with low limits of detection are needed to discover salivary biomarkers in order to develop reliable diagnostic and disease monitoring salivary tests. Lipidomic methods have greatly advanced in recent years with a constant advance in mass spectrometry (MS) and development of MS detectors with high accuracy and high resolution that are able to determine the elemental composition of many lipids.

Salivary alpha-amylase enzyme is a non-invasive biomarker of acute stress in Japanese macaques (Macaca fuscata)

Salivary alpha-amylase (sAA) enzyme functions as a digestive enzyme in many species that consume starch in their diet. Human studies have also revealed that sAA enzyme activity levels are positively correlated with the release of the stress hormone norepinephrine, allowing sAA to act as a biomarker for sympathetic nervous system activity. Recent non-human primate studies have incorporated sAA as a physiological stress marker. However, no published reports have investigated the time course of sAA from a stressful event to return to baseline levels in non-human primates. Furthermore, no validation of sAA as a stress biomarker has been reported for Japanese macaques (Macaca fuscata). This study had two primary aims: (1) to develop a systematic method for non-invasive saliva collection and, (2) to investigate sAA as a biomarker of acute stress in M. fuscata in order to better understand its acute stress-related characteristics. We developed a non-invasive method for cooperative saliva collection using positive reinforcement training (PRT) and tracked individual progress over 595 trials in ten individually housed Japanese macaques. We detected sAA enzyme in M. fuscata via kinetic reaction assay, then performed 22 acute stress tests. Four tests met conditions for interpreting sAA in response to an acute stressor and these results show that on average sAA activity rapidly increased post-stressor (mean ± SD = 4.2 ± 0.9 min) and returned to baseline shortly thereafter (10.4 ± 0.6 min). Our report reveals for the first time the temporal dynamics of sAA when applying acute stress to Japanese macaques and could be a useful tool for assessing animal welfare.

Variation of human salivary alpha-amylase proteoforms in three stimulation models

OBJECTIVES

To evaluate the sAA proteoforms' expression during different stimulation situations.

MATERIALS AND METHODS

This study evaluated the salivary alpha-amylase (sAA) proteoforms' behavior by western blot (WB) analysis and high-resolution mass spectrometry (LC-MS/MS) in different situations that produce increases in sAA activity. For this purpose, six healthy women with a similar body mass index, age, and fit, underwent different sAA stimulation tests, such as acetic acid stimulation, psychological stress using the standardized Trier social stress test, and physical effort using the Cooper treadmill test.

RESULTS

The three models showed an increase in sAA activity. The WB demonstrated seven common bands observed in the six women (band one at 59 kDa, two at 56 kDa, three at 48 kDa, four at 45 kDa, five at 41 kDa, six at 36 kDa, and seven at 14 kDa), in which sAA protein was identified. The individual WB analysis showed that band two, which corresponded to the native non-glycosylated sAA proteoform, had a higher increase after the three sAA stimulation inducers, and this band was also the only proteoform correlated with sAA activity (r = 0.56, P = 0.001). In addition, when the label-free quantification analysis was performed, the different proteoforms showed different responses depending on the type of stimulation.

CONCLUSIONS

This preliminary study showed that the diverse sAA proteoforms' expression depends on the different stimulation models.

CLINICAL RELEVANCE

This study opens new perspectives and challenges for the use of the different alpha-amylase proteoforms as possible biomarkers in addition to the sAA activity.

Factors affecting salivary α-amylase levels measured with a handheld biosensor and a standard laboratory assay

OBJECTIVES

A handheld biosensor for measuring salivary α-amylase (sAA) was developed for convenient on-site measurement. Previous studies reported some discrepancies in sAA levels measured with a biosensor and a standard assay. This study aimed to compare sAA levels measured with three different methods and the factors affecting its levels.

METHODS

Thirty-eight participants collected saliva two times for three measurements. First, the collector strip was placed under the tongue for 2 minutes, then the strip was used to measure sAA level on-site immediately (intraoral biosensor; method 1). Then, a participant pooled the saliva for 4 minutes and collected the saliva into the tube which was aliquoted to measure in a laboratory with a handheld biosensor (extraoral biosensor; method 2) and with a standard enzyme kinetic assay (EKA; method 3). Additional experiments were carried out to compare the levels of sAA measured with differences in pooling time and positioning of the collector strip.

RESULTS

A high correlation of sAA levels between an extraoral and an EKA measurement (r = 0.989) was observed, while sAA levels measured with an intraoral method showed a significant but weaker correlation with either an EKA (r = 0.475) or an extraoral method (r = 0.436). Saliva pooling time and positioning of the collector strip significantly affected sAA levels.

CONCLUSIONS

A handheld biosensor is valid to measure sAA levels extraorally. For an intraoral measurement, pooling time and positioning of the collector strip need to be taken into account.

Biological Aging Parameters Can Be Improved After Autologous Adipose-Derived Stem Cell Injection

Biological aging (BA) is a comprehensive assessment tool for elderly persons. The authors aimed to develop a rat model that can be used to assess BA by evaluating various blood, biochemical, and hormonal parameters and demonstrate that the intravenous administration of autologous adipose-derived stem cells (ADSCs) improves BA. Twelve elderly (aged 20 months) male Sprague-Dawley rats were used in this study and divided into 2 groups: autologous ADSC administration (n = 6) and saline administration (n = 6). The complete blood count, biochemical and hormonal parameters, and antioxidant potential were evaluated before harvesting the rat inguinal fat tissue and intravenous ADSC administration as well as at 1, 3, and 5 weeks after ADSC administration. Adipose-derived stem cells administration regulated blood content, biochemical parameters, renal function, and antioxidant enzymes in elderly rats. Furthermore, changes in several hormonal levels were identified in the ADSC administration group compared with the saline administration group. An assessment model of BA in elderly rats was successfully developed after the intravenous administration of autologous ADSCs. The authors suggest that intravenously injected ADSC treatment may be a valuable method to improve BA.

An experimental investigation into cardiovascular, haemodynamic and salivary alpha amylase reactivity to acute stress in Type D individuals

Type D personality is characterized by increased social inhibition and negative affectivity. Research demonstrates associations between Type D and poor physical health. Maladaptive sympathetic arousal is suggested as a potential mechanism, however, findings are inconsistent and studies mainly focus on basic cardiovascular parameters. The current study examines cardiovascular and haemodynamic parameters in addition to salivary alpha amylase (sAA) as markers of sympathetic stress reactivity in Type D individuals. Healthy adults (N = 75; 33 Type D; aged 18-42; 64% female) completed a multitasking stressor while continuous beat-to-beat cardiovascular function was measured. Saliva samples were obtained at baseline, pre-task, post-task, +10 min and +20 min post-task. Type Ds exhibited dysfunctional cardiovascular reactivity, characterized by blunted total peripheral resistance, slower stroke volume recovery and potentially unhealthy changes in haemodynamic profile. Alpha amylase reactivity was evident, but group differences were not significant. Findings indicate dysregulated sympathetic reactivity in Type D individuals, exemplified by a maladaptive haemodynamic profile.

Elevated salivary alpha-amylase levels at awakening in patients with depression

BACKGROUND

Specific Major Depressive Disorder (MDD) biomarkers could help improve our understanding of MDD pathophysiology and aid in the refinement of current MDD criteria. While salivary cortisol (SC) can differentiate between healthy controls and patients with psychiatric disorders, salivary alpha amylase (sAA), may be a putative candidate biomarker for MDD specifically.

METHODS

In a naturalistic cohort of consecutive out-patients and healthy controls, sAA and SC were determined in 833 participants (97 MDD patients, 142 patients with other mood, anxiety, and/or somatoform (MAS-) disorders, and 594 healthy controls). Samples were collected at 7 different time points (at awakening, after 30, 45, and 60 min, at 10:00 p.m., at 11:00 p.m., and at awakening on day 2).

RESULTS

The mean age of the sample was 43.8 years (SD = 12.9; 63.9% female). Concerning sAA, MDD patients had higher sAA levels upon awakening on two consecutive days (p = 0.04, p = 0.01 respectively), as well as a higher area under the curve with respect to the increase (AUCi; p = 0.04) in comparison to both controls and the other MAS-disorders group. Regarding SC, mean levels of evening SC were elevated in MDD patients (p = 0.049) in comparison to both controls and the other MAS-disorders group. SC values on day 2 after ingestion of dexamethasone were elevated in both MDD patients and the other MAS-disorders group (p = 0.04, p = 0.047 respectively).

CONCLUSIONS

sAA at awakening and not cortisol differentiates MDD from other psychiatric disorders in outpatients. This suggests that sAA may be a valuable candidate biomarker specifically for MDD.

Does sleep deprivation increase the vulnerability to acute psychosocial stress in young and older adults?

Sleep loss and psychosocial stress often co-occur in today's society, but there is limited knowledge on the combined effects. Therefore, this experimental study investigated whether one night of sleep deprivation affects the response to a psychosocial challenge. A second aim was to examine if older adults, who may be less affected by both sleep deprivation and stress, react differently than young adults. 124 young (18-30 years) and 94 older (60-72 years) healthy adults participated in one of four conditions: i. normal night sleep & Placebo-Trier Social Stress Test (TSST), ii. normal night sleep & Trier Social Stress Test, iii. sleep deprivation & Placebo-TSST, iv. sleep deprivation & TSST. Subjective stress ratings, heart rate variability (HRV), salivary alpha amylase (sAA) and cortisol were measured throughout the protocol. At the baseline pre-stress measurement, salivary cortisol and subjective stress values were higher in sleep deprived than in rested participants. However, the reactivity to and recovery from the TSST was not significantly different after sleep deprivation for any of the outcome measures. Older adults showed higher subjective stress, higher sAA and lower HRV at baseline, indicating increased basal autonomic activity. Cortisol trajectories and HRV slightly differed in older adults compared with younger adults (regardless of the TSST). Moreover, age did not moderate the effect of sleep deprivation. Taken together, the results show increased stress levels after sleep deprivation, but do not confirm the assumption that one night of sleep deprivation increases the responsivity to an acute psychosocial challenge.

Low subjective social status in the police is linked to health-relevant changes in diurnal salivary alpha-amylase activity in Swiss police officers

The objective of this study was to assess basal autonomic nervous system (ANS) activity as a pathway linking subjective social status to health in a high-demand work environment. It was hypothesized that officers with a lower status experienced more chronic stress (higher basal ANS activity) and that chronic stress was related to more health problems. Fifty-six male and female Swiss police officers self-reported on subjective social status (country, community, friends, police) and their health (depression, post-traumatic stress, physical symptoms) and collected 12 saliva samples over two days for basal α-amylase activation (sAA) assessment. Multilevel regression analyses revealed that subjective social status in the police and physical symptoms explained a significant part of the variance in diurnal sAA activity patterns. The current findings support the idea that more narrowly defined subjective social status may be more closely linked to biological stress mechanisms. Additionally, sAA activity was specifically related to physical, but not mental health problems. These results suggest that subjective social status referencing one's work environment may be a promising early indicator of health-relevant changes in stress-related physiological systems.

Classroom social experiences in early elementary school relate to diurnal cortisol levels

Social stress has been linked to altered hypothalamic-pituitary-adrenocorticol (HPA) axis activation. During elementary school, children can become exposed to negative peer relations, such as poor appraisal among classroom peers, which is considered a social stressor. However, little is known about the association between classroom peer appraisal and the physiological stress system in children. The goal of this study was to examine the association of peer acceptance and peer non-acceptance with diurnal cortisol concentrations in 222 children from 20 mainstream elementary schools (Mage=6.97years, SD=0.99, 55% boys) in the Netherlands. Saliva samples were collected at awakening, 30min post-awakening, at noon and at 8 pm during a weekend day. From these assessments, the Cortisol Awakening Response (CAR), diurnal cortisol concentration (AUC_g) and diurnal cortisol slope were calculated. Peer nominations of peer acceptance (being liked), and peer non-acceptance (being disliked) were collected across a one year interval. Associations were controlled for peer victimization, age, sex and SES and children's levels of emotional problems and behavioural problems. Results showed that low peer acceptance was associated with heightened diurnal cortisol concentration (i.e., heightened AUG_g), lower cortisol reductions across the day (i.e., less decreasing cortisol slope) and heightened cortisol awakening response (i.e., heightened CAR). Peer non-acceptance and the interaction between peer acceptance and peer non-acceptance (known as peer rejection) were not associated with AUCg, cortisol slope or the CAR. The findings emphasize the association between poor appraisal among classroom peers and children's heightened HPA-axis activation. This underscores the importance of the physiological stress system in studying the consequences of negative peer relations in children.

Influence of the way of reporting alpha-Amylase values in saliva in different naturalistic situations: A pilot study

The objective of this pilot study was to compare the different ways of measuring salivary alpha-amylase (sAA, enzymatic vs. concentration) and to evaluate the influence that the different ways of reporting the results can have in sAA interpretation. For this purpose, sAA was measured by direct quantification and also by an enzymatic assay in three different naturalistic situations, a physical stressor (situation 1) and two mental stressors of different intensity (situations 2 and 3). The results were expressed in three different ways (without correction, multiplied by flow rate and divided by protein concentration). sAA concentration and activity increased just after situations 1 and 3. When values were multiplied by the flow rate, significant changes after situation 1 were detected only for sAA activity but not for sAA concentration, being these changes of lower significance and magnitude that those observed for sAA activity without any correction. In addition, a significant increase in sAA activity was found at T+15 in situation 2. In situation 3 the significant decrease in sAA at T+15 disappeared. When values were divided by protein concentration, there were no significant changes in situations 1 or 3, but a decrease in situation 2 at T+0 and an increase at T+15. sAA activity and concentration showed a significant correlation in all situations. This pilot study points out that the way of expressing sAA can influence the results obtained in different stress models and also their interpretation. Therefore, how sAA is reported and the factors involved in the different ways of expressing sAA, should be taken into consideration for an objective interpretation of sAA values.

Salivary cortisol and α-amylase: subclinical indicators of stress as cardiometabolic risk

Currently, the potential for cardiovascular (CV) stress-induced risk is primarily based on the theoretical (obvious) side effects of stress on the CV system. Salivary cortisol and α-amylase, produced respectively by the hypothalamus-pituitary-adrenal (HPA) axis and the sympathetic-adrenomedullary (SAM) system during stress response, are still not included in the routine evaluation of CV risk and require additional and definitive validation. Therefore, this article overviews studies published between 2010 and 2015, in which salivary cortisol and α-amylase were measured as stress biomarkers to examine their associations with CV/CMR (cardiometabolic risk) clinical and subclinical indicators. A comprehensive search of PubMed, Web of Science and Scopus electronic databases was performed, and 54 key articles related to the use of salivary cortisol and α-amylase as subclinical indicators of stress and CV/CMR factors, including studies that emphasized methodological biases that could influence the accuracy of study outcomes, were ultimately identified. Overall, the biological impact of stress measured by salivary cortisol and α-amylase was associated with CV/CMR factors. Results supported the use of salivary cortisol and α-amylase as potential diagnostic tools for detecting stress-induced cardiac diseases and especially to describe the mechanisms by which stress potentially contributes to the pathogenesis and outcomes of CV diseases.

Assessing the Effects of Music Listening on Psychobiological Stress in Daily Life

Music listening is associated with stress-reducing effects. However, most of the results on music listening and stress were gathered in experimental settings. As music listening is a popular activity of daily life, it is of utmost importance to study the effects of music listening on psychobiological stress in an everyday, daily-life setting. Here, a study protocol is presented that allows the assessment of associations between music listening and psychobiological stress in daily life by noninvasively measuring salivary cortisol (as a marker of the Hypothalamic-Pituitary-Adrenal (HPA) axis) and salivary alpha-amylase (as a marker of the Autonomic Nervous System (ANS)). The protocol includes advice on the study design (e.g., sampling protocol), the materials and methods (e.g., the assessment of psychobiological stress in daily life, the assessment of music listening, and the manual), the selection of participants (e.g., the approval of the institutional review board and inclusion criteria), and the statistical analyses (e.g., the multilevel approach). The representative results provide evidence for a stress-reducing effect of music listening in daily life. Particularly, specific reasons for listening to music (especially relaxation), as well as the presence of others while doing so, increase this stress-reducing effect. At the same time, music listening in daily life differentially affects the HPA axis and ANS functioning, thus emphasizing the need for a multi-dimensional assessment of stress in daily life.

Causes, consequences and biomarkers of stress in swine: an update

BACKGROUND

In recent decades there has been a growing concern about animal stress on intensive pig farms due to the undesirable consequences that stress produces in the normal physiology of pigs and its effects on their welfare and general productive performance. This review analyses the most important types of stress (social, environmental, metabolic, immunological and due to human handling), and their biological consequences for pigs. The physio-pathological changes associated with stress are described, as well as the negative effects of stress on pig production. In addition an update of the different biomarkers used for the evaluation of stress is provided. These biomarkers can be classified into four groups according to the physiological system or axis evaluated: sympathetic nervous system, hypothalamic-pituitary-adrenal axis, hypothalamic-pituitary-gonadal axis and immune system.

CONCLUSIONS

Stress it is a process with multifactorial causes and produces an organic response that generates negative effects on animal health and production. Ideally, a panel of various biomarkers should be used to assess and evaluate the stress resulting from diverse causes and the different physiological systems involved in the stress response. We hope that this review will increase the understanding of the stress process, contribute to a better control and reduction of potential stressful stimuli in pigs and, finally, encourage future studies and developments to better monitor, detect and manage stress on pig farms.

Beyond catecholamines: Measuring autonomic responses to psychosocial context

Despite longstanding interest among human biologists in autonomic responses to socioecological context or culture change, the adoption of autonomic measures has been limited by methodological challenges. Catecholamine secretion is the most direct measure, but not all study designs are amenable to urinary sampling, and blood pressure lacks specificity to the parasympathetic or sympathetic division of the autonomic nervous system. This article reviews three alternative approaches for measuring autonomic responses: salivary α-amylase as a nonspecific autonomic marker, respiratory sinus arrhythmia as a specific parasympathetic marker, and the pre-ejection period as a specific sympathetic marker. Study design considerations are discussed in detail, including ambulatory sampling protocols that permit the evaluation of autonomic responses to everyday life. Researchers interested in how culture and social experience "get under the skin," as well as those concerned with the evolution of social engagement, can benefit from these well-validated biomarkers that are nevertheless relatively novel in human biology. Am. J. Hum. Biol. 28:309-317, 2016. © 2015 Wiley Periodicals, Inc.

Salivary Biomarkers of Chronic Psychosocial Stress and CVD Risks

Background:

The use of salivary biomarkers in stress research is increasing, and the precision and accuracy with which researchers are able to measure these biomarkers have dramatically improved. Chronic psychosocial stress is often linked to the pathogenesis of cardiovascular disease (CVD). Salivary biomarkers represent a noninvasive biological method of characterizing the stress phenomenon that may help to more fully describe the mechanism by which stress contributes to the pathogenesis and outcomes of CVD.

Objectives:

We conducted a systematic review of 40 research articles to identify the salivary biomarkers researchers have most commonly used to help describe the biological impact of chronic psychosocial stress and explore its associations with CVD risk. We address strengths and weaknesses of specimen collection and measurement.

Methods:

We used PubMed, CINAHL, EBSCO host, Web of Science, BIOSIS Previews, Biological Sciences (ProQuest), and Dissertations/Theses (ProQuest) to retrieve 387 initial articles. Once we applied our inclusion/exclusion criteria to specifically target adult human studies dealing with chronic stress rather than acute/laboratory-induced stress, 40 studies remained, which we synthesized using Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria.

Results:

Cortisol was the biomarker used most frequently. Sources of psychosocial stress included job strain, low socioeconomic status, and environmental factors. Overall, psychosocial stress was associated with CVD risks such as vascular pathology (hypertension, blood pressure fluctuation, and carotid artery plaque) as well as metabolic factors such as abnormal blood glucose, dyslipidemia, and elevated cardiac enzymes.

Conclusion:

Diverse salivary biomarkers have been useful in stress research, particularly when linked to CVD risks.

Salivary biomarkers of oxidative stress: A critical review

Human saliva is an increasingly attractive medium for biomarker discovery due to its amenability to noninvasive and repeated sampling, ease of collection and processing, and suitability for single analyte or metabolomic measurements. Salivary biomarkers of oxidative stress reflect local and systemic pathologies and may inform on the diagnosis, prognosis, and therapeutic responsiveness of numerous human diseases. However, for many of the disorders investigated, data reporting on alterations in salivary redox homeostasis are often highly conflicted across studies. We surveyed the available biomedical literature on this topic and noted significant discrepancies in the study designs, target populations, and operating procedures which likely contribute to the discordant data sets reported. Based on these observations, guidelines are provided to minimize interlaboratory variability in redox biomarker discovery based on human saliva.

Morphological changes in the salivary acini after in vivo cholinergic stimulation

AIMS

Overactive bladder syndrome treated by muscarinic receptor antagonists may be complicated by reduced salivation. Cholinergic agonists may reverse this effect. The aim of the present study was to determine the antagonizing effect of a cholinergic agonist (carbachol) on a muscarinic receptor antagonist (oxybutynin) in the submandibular acini in a rat model.

METHODS

Forty male Sprague Dawley rats were divided into three groups: Group I (control), Group II (vehicle), and Group III (treatment). Group III was subdivided so Group IIIa was treated with a muscarinic receptor antagonist (oxybutynin) for 1 week, Group IIIb was treated with oxybutynin for 3 weeks, and Group IIIc was treated with oxybutynin for 1 week and oxybutynin and a cholinergic agonist (carbachol) for 2 weeks. Histological and ultrastructural studies were performed on submandibular glands.

RESULTS

Group IIIa showed moderate atrophic changes in the serous acini and ducts. Group IIIb showed serous acini with distorted wall, widening of the inter-lobar space, and deposition of mononuclear cells in the connective tissue. Group IIIc had serous acini similar to Group I, with mildly dilated inter-lobar ducts, but some serous acini revealed double nuclei and the inter-lobar duct showed luminal vacuolations. Ultrastructural studies confirmed histological results.

CONCLUSIONS

Muscarinic receptor antagonist administration led to changes in the submandibular gland of rats, while concomitant administration of cholinergic agonists seemed to counteract these atrophic changes. Additional studies should assess carbachol as a cholinergic agonist in treating dry mouth in patients with overactive bladder syndrome who are taking the muscarinic receptor. Neurourol. Urodynam. 35:574-581, 2016. © 2015 Wiley Periodicals, Inc.

Multiple time courses of salivary alpha-amylase and dimensions of affect in adolescence

Previous research has illustrated associations among daily experiences, emotions and stress-responding physiological systems. Recently, investigators have examined salivary alpha-amylase (sAA), a surrogate marker of the autonomic nervous system, and its associations with affect. The current study examined associations among affective valence, arousal and sAA across three different time courses at the momentary, daily and inter-individual level to understand varying influences of adolescents' daily emotional experiences on sAA reactivity and diurnal sAA activity. Adolescents (N=82) provided salivary samples and diary reports of affect and experiences five times a day for three consecutive days. They also completed self-report questionnaires on trait affect. Findings from multilevel growth curves demonstrated that adolescents in our sample displayed typical sAA diurnal rhythms with levels dropping 30 min after waking and then increasing across the day to a peak in the late afternoon. Within person momentary experiences of high arousal positive affect were associated with momentary sAA reactivity. Prior day experiences of high arousal negative affect were associated with a greater amylase awakening response (i.e., greater decrease) and flatter slopes the next day. Trait positive affect was also associated with flatter sAA slopes. Our findings suggest that both affective arousal and valence should be accounted for when examining differences in sAA reactivity and diurnal patterns. Further, our results indicated that emotion-physiology transactions among adolescents occur over varying time scales for salivary alpha-amylase as well as cortisol.

Psychometric and biohormonal indices of dental anxiety in children. A prospective cohort study

The stress of dental treatment often elicits negative emotions in children, expressed as dental fear or anxiety. Highly anxious children obstruct treatment and avoid therapy, further amplifying oral health problems. The aim of this study was to examine the neuroendocrine and autonomic nervous system responses to dental treatment and their possible interactions and associations with psychometric indices of anxiety, caries, previous dental experience, anesthesia, age and gender in school children. Upon informed consent, saliva was obtained from 97 children (59% males, mean age ±  SD: 89.73 ± 15 months) in the Clinic of pediatric dentistry before treatment, immediately post-treatment and at the recall visit to determine cortisol and salivary alpha-amylase (sAA) levels. Dental and general anxiety was assessed through specific questionnaires completed by the children. Compared to pre-treatment, cortisol levels were increased following treatment, while sAA levels were higher at the recall. Pre- and post-treatment cortisol and sAA responses were positively correlated. Dental and general anxiety questionnaire scores were also significantly correlated with each other. The integrated autonomic and neuroendocrine responses prior to treatment were correlated with state anxiety and those following treatment with dental anxiety. However, univariable and multivariable linear regression analysis associated post-treatment cortisol, but not sAA, levels with dental anxiety. No associations of cortisol or sAA responses with caries, age, gender, previous dental experience or anesthesia were detected. These data provide some evidence that both sAA and cortisol levels are altered in children in anticipation or during dental treatment, but only cortisol levels are associated to dental anxiety.

The relationship between the level of salivary alpha amylase activity and pain severity in patients with symptomatic irreversible pulpitis

Objectives

Assessment of dental pain severity is very challenging in dentistry. Previous studies have suggested that elevated salivary alpha amylase may contribute to increased physical stresses. There is a close association between salivary alpha amylase and plasma norepinephrine under stressful physical conditions. The aim of this study was to evaluate the relationship between pain severity and salivary alpha amylase levels in patients with symptomatic irreversible pulpitis.

Materials and Methods

Thirty-six patients (20 females and 16 males) with severe tooth pain due to symptomatic irreversible pulpitis were selected. The visual analogue scale (VAS) score was used to assess the pain severity in each patient. Unstimulated whole saliva was collected, and the level of alpha amylase activity was assessed by the spectrophotometric method. Statistical analysis was performed using SPSS 13.

Results

The level of alpha amylase was significantly increased in the saliva in association with pain severity assessed by VAS. The salivary alpha amylase was also elevated with increased age and in males.

Conclusions

There was a significant correlation between the VAS pain scale and salivary alpha amylase level, which indicates this biomarker may be a good index for the objective assessment of pain intensity.

Evening salivary alpha-amylase, major depressive disorder, and antidepressant use in the Netherlands Study of Depression and Anxiety (NESDA)

Salivary alpha-amylase (sAA) may be a suitable index for sympathetic activity and dysregulation of the autonomic nervous system. The relationship between antidepressants and depression with sAA levels was studied, since antidepressants were previously shown to have a profound impact on heart rate variability as an ANS indicator. Data are from 1692 participants of the Netherlands Study of Depression and Anxiety (NESDA) who were recruited from the community, general practice, and specialized mental health care. Differences in evening sAA levels were examined between patient groups (i.e., 752 current major depressive disorder [MDD], 611 remitted MDD, and 329 healthy controls) and between 46 tricyclic antidepressant (TCA) users, 307 selective serotonin reuptake inhibitor (SSRI) users, 97 users of another antidepressant, and 1242 non-users. Each participant sampled twice at 22.00h and 23.00h. In multivariable analysis, there was a trend over the three groups with increasing sAA levels from controls to remitted MDD to current MDD that approached significance. Furthermore, in comparison to non-users of antidepressants, TCA rather than SSRI users showed higher sAA levels, that persisted after multivariable adjustment. The present study shows that higher evening sAA levels in depressed patients, indicative of an increased sympathetic activity, may be induced by TCAs.

Assessing agreement between salivary alpha amylase levels collected by passive drool and eluted filter paper in adolescents with cancer

PURPOSE/OBJECTIVES

To assess the validity of filter paper (FP) against the gold standard of passive drool (PD) for collecting salivary alpha amylase as a surrogate biomarker of psychological stress in adolescents with cancer.

DESIGN

Part of a longitudinal, descriptive study of symptoms in adolescents with cancer during chemotherapy.

SETTING

A pediatric hematology/oncology treatment center.

SAMPLE

33 saliva sample pairs from nine adolescents with cancer, aged 13-18 years.

METHODS

Salivary alpha amylase was collected by PD and FP at four time points during a cycle of chemotherapy: days 1 (time 1) and 2 (time 2) of chemotherapy, day 7-10 (time 3), and day 1 of the next cycle (time 4). A random effects regression was used to assess the correlation between PD and FP values, and a Bland Altman analysis was conducted to assess agreement between the values.

MAIN RESEARCH VARIABLES

Salivary alpha amylase.

FINDINGS

The estimated correlation between PD and FP values was r = 0.91, p < 0.001. Regression results were also used to rescale FP values to the levels of the PD values because the FP values were on a different scale than the PD values. The Bland Altman analysis revealed that the agreement between the rescaled FP values and PD values was not satisfactory.

CONCLUSIONS

Eluted FP may not be a valid method for collecting salivary alpha amylase in adolescents with cancer.

IMPLICATIONS FOR NURSING

Psychological stress in adolescents with cancer may be linked to negative outcomes, such as greater symptom severity and post-traumatic stress disorder. Nurses need valid, efficient, biobehavioral measures to assess psychological stress in the clinical setting.

Concurrent attenuated reactivity of alpha-amylase and cortisol is related to disruptive behavior in male adolescents

Attenuated reactivity of salivary alpha-amylase has been proposed as a specific sympathetic marker of disruptive behavior in juveniles and may have additional value to studying other autonomic parameters and hypothalamic-pituitary-adrenal axis activity. Investigating the interrelationships between neurobiological parameters in relation to juvenile disruptive behavior may enhance insight into the complex mechanisms at play. We investigated salivary alpha-amylase, cortisol, heart rate (HR), and heart rate variability (HRV) in response to a standardized public speaking task, and examined interactions between these parameters in relation to disruptive behavior. Participants were 48 delinquent male adolescents (mean age 18.4 years, SD 0.9), with and without a disruptive behavior disorder (resp. DP+, DP-) and 16 matched normal controls (NC). A structured psychiatric interview as well as the Youth Self Report and Child Behavior Checklist were administered to assess disruptive behavior. Alpha-amylase and cortisol reactivity, but not HR or HRV, showed significant inverse associations with dimensional measures of disruptive behavior. Moreover, both cortisol and alpha-amylase reactivity were significantly lower in the DP+ group as compared to the NC group. The mentioned relationships remained present when nicotine use was entered as a covariate. Combining alpha-amylase and cortisol in one model explained a larger part of the variance of disruptive behavior than either single parameter. There were no interactions between alpha-amylase and cortisol or HRV in relation to disruptive behavior. Attenuated alpha-amylase responsivity to stress is a correlate of disruptive behavior in late-adolescent males. Although nicotine use explains a considerable part of the variance of disruptive behavior, both alpha-amylase and cortisol are related to disruptive behavior, over and above the effect of nicotine use. Combining alpha-amylase and cortisol improved insight into neurobiological mechanisms involved with disruptive behavior; concurrent low reactivity of both parameters was related to higher levels of disruptive behavior.

Diagnostic performance of initial salivary alpha-amylase activity for acute myocardial infarction in patients with acute chest pain

BACKGROUND

To rule out acute myocardial infarction (AMI) in chest pain patients constitutes a diagnostic challenge to emergency department (ED) physicians.

STUDY OBJECTIVES

To evaluate the diagnostic value of measuring salivary alpha-amylase (sAA) activity for detecting AMI in patients presenting to the ED with acute chest pain.

METHODS

sAA activity was measured in a prospective cohort of 473 consecutive adult patients within 4 h of onset of chest pain. Comparisons were made between patients with a final diagnosis of AMI and those with non-AMI. Univariate analysis and multiple logistic regression model were used to identify independent clinical predictors of AMI.

RESULTS

Initial sAA activity in the AMI group (n = 85; 266 ± 127.6 U/mL) was significantly higher than in the non-AMI group (n = 388; 130 ± 92.8 U/mL, p < 0.001). sAA activity levels were also significantly higher in patients with ST elevation AMI (n = 53) compared to in those with non-ST elevation AMI (n = 32) (300 ± 141.1 vs. 210 ± 74.1 U/mL, p < 0.001). The area under the receiver operating characteristic curve of sAA activity for predicting AMI in patients with acute chest pain was 0.826 (95% confidence interval [CI] 0.782-0.869), with diagnostic odds ratio 10.87 (95% CI 6.16-19.18). With a best cutoff value of 197.7 U/mL, the sAA activity revealed moderate sensitivity and specificity as an independent predictor of AMI (78.8% and 74.5%).

CONCLUSIONS

High initial sAA activity is an independent predictor of AMI in patients presenting to the ED with chest pain.

α-Amylase as a reliable and convenient measure of sympathetic activity: don't start salivating just yet!

Recent years have seen a growing interest in salivary α-amylase (sAA) as a non-invasive marker for sympathetic nervous system (SNS) activity. Saliva offers many advantages as a biomarker fluid and sAA is one of its most plentiful components. sAA is a digestive enzyme that breaks down starch, which provides a simple means of quantification by measuring its enzymatic activity. This commentary will address a number of common misconceptions and methodological issues that surround the use of sAA as a marker of SNS activity and limit its utility in biobehavioral research. The usefulness of sAA as an SNS marker is undermined by the fact that the parasympathetic nerves also play a significant role in sAA release. Local parasympathetic nerves regulate sAA activity via: (1) α-amylase release from glands that are solely or mainly parasympathetically innervated; (2) via synergistic sympathetic-parasympathetic effects on protein secretion (known as 'augmented secretion'); and (3) via effects on salivary flow rate. Regarding methodology, we discuss why it is problematic: (1) to ignore the contribution of salivary flow rate; (2) to use absorbent materials for saliva collection, and; (3) to stimulate saliva secretion by chewing. While these methodological problems can be addressed by using standardized and timed collection of unstimulated saliva, the physiological regulation of sAA secretion presents less resolvable issues. We conclude that at present there is insufficient support for the use and interpretation of sAA activity as a valid and reliable measure of SNS activity.

Validation of an Automated Method for Salivary Alpha-Amylase Measurements in Pigs (Sus Scrofa Domesticus) and its Application as a Stress Biomarker

The aim of the current study was to validate an automated spectrophotometric method for salivary alpha-amylase measurement in pigs and evaluate its possible application as a noninvasive stress biomarker. The analytical validation included intra- and interassay precision, linearity under dilution, and limit of detection. In addition, to study the possible use of salivary alpha-amylase as a possible stress marker, 12 crossbred growing pigs of 3–4 months of age were subjected to restraint stress by a nasal snare for at least 1 min, and saliva samples were obtained at different time points. The results of analytical validation indicated that the method was precise and able to measure alpha-amylase in a linear manner. The results obtained in the stress test showed a significant increase in salivary alpha-amylase activity. Although other factors influencing this enzyme activity should be studied, these preliminary results indicate that salivary alpha-amylase could be a reliable biomarker of stress in pigs.

Salivary alpha-amylase and cortisol among pentecostals on a worship and nonworship day

OBJECTIVES

This investigation used a biomarker of sympathetic nervous system activity novel to biocultural research to test the hypothesis that engaging in religious worship activities would reduce baseline stress levels on a non-worship day among Pentecostals.

METHODS

As detailed in Lynn et al. (submitted for publication), stress was measured via salivary cortisol and α-amylase among 52 Apostolic Pentecostals in New York's mid-Hudson Valley. Saliva samples were collected at four predetermined times on consecutive Sundays and Mondays to establish diurnal profiles and compare days of worship and non-worship. These data were reanalyzed using separate analyses of covariance on α-amylase and cortisol to control for individual variation in Pentecostal behavior, effects of Sunday biomarkers on Monday, and other covariates.

RESULTS

There was a significant decrease in cortisol and an increase in α-amylase on a non-worship day compared with a service day. Models including engagement in Pentecostal worship behavior explained 62% of the change in non-service day cortisol and 73% of the change in non-service day α-amylase.

CONCLUSIONS

Engagement in Pentecostal worship may be associated with reductions in circulatory cortisol and enhancements in α-amylase activity.

Developmental validation of a point-of-care, salivary α-amylase biosensor

The translation of salivary alpha-amylase (sAA) to the ambulatory assessment of stress hinges on the development of technologies capable of speedy and accurate reporting of sAA levels. Here, we describe the developmental validation and usability testing of a point-of-care, colorimetric, sAA biosensor. A disposable test strip allows for streamlined sample collection and a corresponding hand-held reader with integrated analytic capabilities permits rapid analysis and reporting of sAA levels. Bioanalytical validation utilizing saliva samples from 20 normal subjects indicates that, within the biosensor's linear range (10-230 U/ml), its accuracy (R(2)=0.989), precision (CV<9%), and measurement repeatability (range -3.1% to +3.1%) approach more elaborate laboratory-based, clinical analyzers. The truncated sampling-reporting cycle (<1 min) and the excellent performance characteristics of the biosensor has the potential to take sAA analysis out of the realm of dedicated, centralized laboratories and facilitate future sAA biomarker qualification studies.

Salivary alpha-amylase stress reactivity across different age groups

tract Salivary alpha-amylase (sAA) increases rapidly in response to psychosocial stress in young adults, but no direct comparisons between different age groups across the life span have been made. Secretion of sAA and cortisol was assessed in children, young adults, and older adults after exposure to the Trier Social Stress Test. Additionally, cardiovascular activity was measured in both adult groups. Older adults showed attenuated sAA, heart rate (HR), and heart rate variability (HRV) responses. Furthermore, we found higher sAA but lower cortisol at baseline as well as lower sAA and cortisol responses in children. Age x sex interactions were observed only for cortisol with higher responses in older male participants. No associations between the parameters were found. These results implicate sAA as an alternative or additional sympathetic stress marker throughout the life span, with marked and rapid stress responsiveness in three relevant age groups.

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.

[Measurement of amylase in saliva collected by salivette]

BACKGROUND

Saliva is increasingly being used as a specimen for systemic disease as well as for oral health status. Especially, salivary amylase has been studied as an excellent index for psychological stress. Authors evaluated the measurement of salivary amylase activities collected by Salivettes (Sarstedt, Germany).

METHODS

Saliva specimens were collected from 13 healthy adults between 10:00 and 11:00 a.m. Participants were asked to gently chew tampons of Salivettes for 1 min. Immediately after collection, all specimens were stored frozen. On the day of testing, they were centrifuged after thawing and diluted with distilled water. Amylase was measured by Dimension RxL Max (Dade Behring Inc., USA). We evaluated precision, linearity, and recovery rate of Salivette. Amylase activities between collection of saliva by Salivette and passive drool were compared, and also the changes of amylase by the storage temperature were evaluated.

RESULTS

Intra-run CVs for three levels of amylase were excellent. Between-day CVs and total CVs were good only for mid and high levels. A good linear relationship was found at all diluted levels. Dosing Salivettes with 2 mL, 1.5 mL, and 1 mL yielded sample recovery 85.5+/-2.4%, 82.4+/-1.5%, and 72.2+/-3.1%, respectively and amylase recovery 78.9+/-10.9%, 74.1+/-13.7%, and 37.3+/-26.9%, respectively. Amylase by Salivette and passive drool were correlated well (r=0.757), although they showed a significant difference. Amylase activity was not affected by the storage temperature.

CONCLUSIONS

Measurement of salivary amylase using Salivette could be a useful test having good intra-run CVs and linearity. More than 1.5 mL of saliva would be needed to have more than 70% recovery of Salivette.