A review of salivary composition changes induced by fasting and its impact on health

Human saliva is an indispensable fluid that maintains a healthy oral cavity which otherwise can lead to oral diseases(dental caries and periodontitis).In addition,salivary metabolites and microbiome profile provide early detection of systemic diseases such as cancer and obesity.Salivary diagnostic has gained popularity due to its non-invasive sampling technique.Fasting(abstinence from food or drink or both)research for weight loss and improve health is common,but studies using fasting saliva are scarce.Some metabolites in fasting saliva have been reported with interesting results,which can be enhanced by considering different confounding factors.For example,fasting saliva contains higher salivary nitrite,which is related to nitric oxide(NO).NO is a vasodilator supporting the healthy function of endothelial cells and its deficiency is connected to many diseases.The timely supply of NO through exogenous and endogenous means is highlighted and the potential advantage of fasting salivary composition changes in relation to COVID-19 infection is speculated.This review aims to provide a general discussion on the salivary composition,properties,and functions of the whole saliva,including the health benefits of fasting.

Saliva:a challenging human fluid to diagnose brain disorders with a focus on Alzheimer's disease

Biomarkers are molecules of biological processes that help in both the diagnosis of human diseases and in follow-up assessments of therapeutic responses. Biomarkers can be measured in many human fluids, such as blood, cerebrospinal fluid, urine, and saliva. The-omics methods(genomics, RNomics, proteomics, and metabolomics) are useful at measuring thousands of markers in a small volume. Saliva is a human fluid that is easily accessible, without any ethical concerns. Yet, saliva remains unexplored in regard to many human disease biomarkers. In this review, we will give an overview on saliva and how it can be influenced by exogenous factors. As we focus on the potential use of saliva as a diagnostic tool in brain disorders(especially Alzheimer's disease), we will cover how saliva is linked to the brain. We will discuss that saliva is a heterogeneous human fluid, yet useful for the discovery of biomarkers in human disorders. However, a procedure and consensus that is controlled, validated, and standardized for the collection and processing of saliva is required, followed by a highly sensitive diagnostic approach.

Effects of the degree of oral processing on the properties of saliva-participating emulsions:using stewed pork with brown sauce as the model

This work investigated the changes in properties of saliva-participating emulsions during different oral processing stages(the whole process from intake to swallowing was divided into five stages,i.e.,20%,40%,60%,80%and 100%stage).The stewed pork with brown sauce was masticated and the emulsion was collected for the determination of emulsion stability,droplet size,ζ-potential,interfacial tension,and microstructure.The results showed that the emulsion stability increased gradually during the oral processing and reached the highest level near the swallowing point.The droplet size of emulsion showed a significant downward trend(P<0.05).Microstructure observations also found different degrees of reduction in fat droplets size at different stages of oral processing.In addition,theζ-potential of food boluses emulsion was decreased from-16.4 mV to-41.2 mV and the interfacial tension decreased by 52.6%before and after oral progressing.In conclusion,the oral processing of stewed pork with brown sauce was essentially a process in which fat was constantly emulsified,and saliva might act as an emulsifier.This study provides new insights on understanding the oral processing process and sensory changes of fat.

Changes of free radicals and digestive enzymes in saliva in cases with deficiency inspleen-yin syndrome

Objective：To explore the nature of deficiency in spleen-yin syndrome,which could provide scientific theoretical support and practical guidance for clinical Traditional Chinese Medicine（TCM）syndrome differentiation based on biology,and had a strong clinical significance.Methods：Serum Cu and Zn were detected by atomic absorption spectrophotometer,serum vitamin E by high performance liquid chromatography,serum vitamin C by 2,4-Dinitrophenylhydrazine Colorimetry,total superoxide dismutase（SOD）and Cu and Zn- SOD by the xanthine oxidase method,and malondialdehyde（MDA）by the 2-thiobarbituric acid method（TBA）.Total antioxidant capacity was detected by a colorimetry kit.Amylase Activity was detected by an automatic biochemical analyzer.Lysozyme was detected by lysozyme detection plate,the diameter of bacteriolysis circle was measured and the corresponding content of lysozyme was obtained from a table of standard curve values.Results： No significant difference in total SOD and Cu,Zn-SOD was found between deficiency in spleen-yin group and normal group.However,such factors in deficiency in kidney-yin group were significantly lower than the other groups（P〈0.05）.The MDA content in both deficiency in spleen-yin group and deficiency in kidney-yin group were significantly higher than that of normal group（P〈0.05）,while the total antioxidant capacity was significantly lower than normal group（P〈0.05）.The vitamin E content in deficiency in kidney-yin group was significantly lower than that in the other two groups（P〈0.05）.No significant difference in the contents of vitamin C,Cu and Zn were observed in these groups.The Zn/Cu level in deficiency in kidney-yin group and the vitamin E level in deficiency in spleen-yin group decreased,but with no significant difference.Amylase activity in unit time in cases with deficiency in spleen-yin was lower than and had significant differences with that in normal cases,and higher than that in cases with deficiency in kidney-yin.The sectional velocity of saliva and the ratio of lysozyme in normal case group were significantly higher than other two groups,while deficiency in the spleen-yin group was significantly higher than the deficiency in kidney-yin group.Conclusion：All the results indicated that the objective pathological mechanism between the deficiency in spleen-yin and deficiency in kidney-yin was different.

Potential use of a dried saliva spot(DSS)in therapeutic drug monitoring and disease diagnosis

In recent years,scientific researchers have increasingly become interested in noninvasive sampling methods for therapeutic drug monitoring and disease diagnosis.As a result,dried saliva spot(DSS),which is a sampling technique for collecting dried saliva samples,has been widely used as an alternative matrix to serum for the detection of target molecules.Coupling the DSS method with a highly sensitive detection instrument improves the efficiency of the preparation and analysis of biological samples.Furthermore,dried blood spots,dried plasma spots,and dried matrix spots,which are similar to those of the DSS method,are discussed.Compared with alternative biological fluids used in dried spot methods,including serum,tears,urine,and plasma,saliva has the advantage of convenience in terms of sample collection from children or persons with disabilities.This review aims to provide integral strategies and guidelines for dried spot methods to analyze biological samples by illustrating several dried spot methods.Herein,we summarize recent advancements in DSS methods from June 2014 to March 2021 and discuss the advantages and disadvantages of the key aspects of this method,including sample preparation and method validation.Finally,we outline the challenges and prospects of such methods in practical applications.

拟南芥MtN3/saliva基因家族分析

MtN3/saliva基因家族是含有2个MtN3/saliva跨膜结构域的膜整合蛋白,其成员广泛存在于真核生物中.目前对该家族功能研究较少,对其跨膜结构域的分子功能还不清楚.在拟南芥中该家族有18个成员,除了最近克隆的RPG1以外其他MtN3/saliva基因的功能均不清楚.对拟南芥MtN3/saliva基因家族进行了较为全面的分析,包括基因结构、染色体分布、蛋白结构域、系统进化关系、基因表达谱等.对其中预测在花药中高表达的4个基因进行了实时定量PCR分析,证实有3个基因在花中高效表达.这些结果促进了对MtN3/saliva基因家族的深入了解.

Sampling Small Volumes of Saliva for Determination of the Stress Hormone α-Amylase: A Comparative Methodological Study

Two sampling devices that allow saliva collection through absorption to a cotton roll (Salivette?-method) or to small cotton pellets (VectaSpinTM Micro [VSM]-method) were studied. Any loss of salivary alpha-amylase (sAA) activity in relation to the saliva volume absorbed and harvested by centrifugation was examined. A pooled saliva sample prepared from stimulated whole saliva (collected by drooling) of 30 subjects was used. Three different saliva volumes (2.9 ml, 1.5 ml, and 0.8 ml) were tested on cotton rolls and two (0.03 ml, and 0.015 ml) on cotton pellets. The sample sAA activity was determined from the hydrolysis of 2-chloro-4-nitrophenyl-α-D-maltotrioside. In comparison with the original drooling sample, no sAA loss was observed in 1.5 ml samples tested with Salivette, while a significant decrease of activity was recorded with smaller volumes. VSM collected samples showed a non-volume dependent decrease of sAA activity of about 25%. Salivette requires large saliva volumes to allow an accurate sAA estimation. With cases of limited saliva access, VSM may be a suitable sampling device.

Effect of Pre-Analytical Conditions on Salivary Nitrite Levels

The aim of the present paper was to analyze the influence of sampling and storage procedures on nitrite con- centration values in the saliva of healthy persons. The samples were obtained and stored under varied condi- tions, and processed using the Griess method. Results: when the salivary nitrite concentration was measured immediately after collection a significant dependence on the collection time was observed. A mean value of 94 μmol/L (range 3 - 625) was obtained at 8:30 am. This value decreased significantly with time (p < 0.05) reaching a value of 68 at 12:30 noon. Concerning the sample storage, a significant increase in the nitrite concentration was observed after 2 hrs, either at 4?C or at room temperature (p < 0.05). In spite of the high variability between individuals the values for each individual showed a marked constancy independent of the sampling day. According to our results, by controlling pre-analytical parameters, principally sampling and storage procedures, reproducibility is improved.

Salivary flow rates, per se, may not serve as consistent predictors for dental caries

Background: This clinical study evaluated the effects of salivary flow rate, age, race, health status and medications on the incidence of caries. Methods:Cauca-sian and African-American men and women (n = 501), aged 22-93 years participated in the study. Stimulated (S) and unstimulated (U) parotid (P) and submandibular glands (SM) salivary secretions were collected. Stimulated whole saliva (SWS) was collected as control. Glandular stimulation was achieved using 2% citric acid at 30-second intervals to the dorsal surface of the tongue. Salivary flow rates (SFR) were calculated by total weight of saliva divided by 5 minutes and expressed in ml/minute. Coronal caries were scored using the NIDR DMFS index. Carious lesions were classified according to tooth surfaces by a calibrated single examiner. Spearman correlation coefficients were calculated to determine the association between SFR with age and percentage of carious teeth. Multiple regression analyses were calculated at (p < 0.05). Results: The variables gender, race, age, health status, medication usage and salivary function were not predictors for dental disease. Additionally, these risk factors were not risk factors for missing teeth. Conclusions: In conclusion, cross-sectional investigations are limited in their ability to identify the relevant variables for disease prediction. In addition, clinical and basic science investigations will be necessary to assess risk factors for dental caries.

High-Resolution ¹H NMR Investigations of the Oxidative Consumption of Salivary Biomolecules by a Tooth-Whitening Formulation: Relevance to Safety Issues

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

Role of dental plaque,saliva and periodontal disease in Helicobacter pylori infection

Helicobacter pylori(H.pylori)infection is one of the most common bacterial infections in humans.Although H.pylori may be detected in the stomach of approximately half of the world’s population,the mechanisms of transmission of the microorganism from individual to individual are not yet clear.Transmission of H.pylori could occur through iatrogenic,fecal-oral,and oral-oral routes,and through food and water.The microorganism may be transmitted orally and has been detected in dental plaque and saliva.However,the role of the oral cavity in the transmission and recurrence of H.pylori infection has been the subject of debate.A large number of studies investigating the role of oral hygiene and periodontal disease in H.pylori infection have varied significantly in terms of their methodology and sample population,resulting in a wide variation in the reported results.Nevertheless,recent studies have not only shown that the microorganism can be detected fairly consistently from the oral cavity but also demonstrated that the chances of recurrence of H.pylori infection is more likely among patients who harbor the organism in the oral cavity.Furthermore,initial results from clinical trials have shown that H.pylori-positive dyspeptic patients may benefit from periodontal therapy.This paper attempts to review the current body of evidence regarding the role of dental plaque,saliva,and periodontal disease in H.pylori infection.

Anti-oxidation actions of curcumin in two forms of bed rest:oxidative stress serum and salivary markers

Objective:To determine the preventive effects of curcumin on peroxidative damage under two bed rest conditions.Methods:20 healthy male(10 with curcumin and 10 without curcumin ) volunteers were selected.They were studied before,during,and just on bed rest conditions at -6°head-down-tilt(HDT) bed rest and bed rest position(BD) for 10 days.We measured the salivary and serum oxidative markers such as Malonaldehyde,8-hydroxydeoxyguanosine, vitamin C and E just before HDT & BD.during HDT & BD experiment,and in course time of recovery with curcumin and without curcumin groups.Results:The values of serum and salivary vitamin C & E showed statistically significant decrease in both bed rest conditions as compared to those of the conditions before and during the recovery stage.However,these levels were not significantly lowered in curcumin groups in contrast to the groups without curcumin (P】0.05).MDA and 8-OHdG levels showed significant increase in simulating microgravity and zero gravity conditions as compared to those before and in the recovery stage.However,these levels were lower in curcumin groups in contrast to the groups without curcumin(P【0.05).Serum and salivary correlation analysis revealed a strong and highly significant correlation for MDA. vitamin C & E and 8 dihydro-2 deoxyguanosine(8-OHdG) in the conditions before,during and in the recovery periods in both bed rest conditions.Since saliva collection is easy and noninvasive, measurements of salivary marker levels may prove to be useful in the space research. Conclusions:Curcumin prevents peroxidative damage in both bed rest conditions.Further study is required on antioxidation actions of curcumin in space microgravity conditions.

Saliva in the diagnosis of diseases

Saliva is secreted from the salivary glands and has multiple functions, including mouth cleaning and protection, antibacterial effects and digestion. With the rapid advancement in salivaomics, saliva is well recognized as a pool of biological markers. Saliva, as a non-invasive and safe source, could be a substitute for blood in the diagnosis and prognosis of diseases. This review summarizes the latest advancements in saliva-related studies and addresses the potential value of saliva in the early diagnosis of oral diseases, such as dental caries and periodontal disease, as well as cancer, diabetes and other systemic disorders. Saliva biomarkers range from changes in the biochemical indices of DNA, RNA and proteins to the diversification of microbiota structures. This study integrates data reported in the recent literature and discusses the clinical significance and prospects for the application of saliva in the early diagnosis of diseases, translational medicine and precision medicine.

Multispecies communities:interspecies interactions influence growth on saliva as sole nutritional source

Human oral bacteria live in multispecies communities in the biofilm called dental plaque. This review focuses on the interactions of seven species and the ability of each species individually and together with other species to grow on saliva as the sole source of nutrient. Community formation in biofihns in flow cells is monitored using species-specific fluorophore-conjugated immunoglobulin Gy and images are captured by confocal microscopy. Early colonizing veillonellae emerge from this review of interspecies interactions in saliva as a critical genus that guides the development of multispecies communities. Highly selective interspecies recognition is evident as initial colonizers pair with early and middle colonizers to form multispecies communities that grow on saliva.

Interferon-c and interleukin-4 detected in serum and saliva from patients with oral lichen planus

Our previous salivary study had demonstrated an apparent T helper 2 （Th2）-predominance in saliva of oral lichen planus （OLP） patients and suggested a potential of salivary interleukin-4 （IL-4） as a biomarker for monitoring disease severity. To further determine the consistency of Th1/Th2 bias of OLP, this study investigated the expression profile of interferon-γ （IFN-γ） and IL-4 in serum and the relationship of the serum levels of these cytokines with their saliva partners. Sixty ethnic Chinese patients with OLP （40 of the erythematous/ulcerative form and 20 of the reticular form） were recruited for this study, with 40 age-sex-matched healthy volunteers as control group. IFN-γ and IL-4 levels in serum and paired saliva samples were screened by enzyme-linked immunosorbent assay. OLP patient showed a low-level IFN-γ but high-level IL-4 expression profile in both serum and saliva, with a lower IFN-γ/IL-4 ratio. Serum IL-4 level in the erythematous/ulcerative group was significantly higher than that in the reticular group. Serum levels of IFN-γ and IL-4 were significantly and positively correlated with their saliva partners. These results provided more evidence for Th2 cytokine- predominant immune imbalance in OLP, as well as the potential of IL-4 as the biomarker for monitoring severity of OLP.

Bioinformatics advances in saliva diagnostics

There is a need recognized by the National Institute of Dental ＆ Craniofacial Research and the National Cancer Institute to advance basic, translational and clinical saliva research. The goal of the Salivaomics Knowledge Base （SKB） is to create a data management system and web resource constructed to support human salivaomics research. To maximize the utility of the SKB for retrieval, integration and analysis of data, we have developed the Saliva Ontology and SDxMart. This article reviews the informatics advances in saliva diagnostics made possible by the Saliva Ontology and SDxMart.

Saliva as a non-invasive diagnostic tool for inflammation and insulin-resistance

Saliva has been progressively studied as a non-invasive and relatively stress-free diagnostic alternative to blood. Currently, saliva testing is used for clinical assessment of hormonal perturbations, detection of HIV antibodies, DNA analysis, alcohol screening, and drug testing. Recently, there has been increasing interest in evaluating the diagnostic potential of saliva in obesity, inflammation, and insulin-resistance. Current literature has demonstrated elevated levels of inflammatory biomarkers including C-reactive protein, tumor necrosis factor-α, interleukin-6, and interferon-γ in saliva of obese/overweight children and adults. Salivary antioxidant status has also been studied as a measure of oxidative stress in individuals with type 2 diabetes. Further, several studies have demonstrated correlations of salivary markers of stress and insulin resistance including cortisol, insulin, adiponectin, and resistin with serum concentrations. These findings suggest the potential diagnostic value of saliva in health screening and risk stratification studies, particularly in the pediatric population, with implications for inflammatory, metabolic and cardiovascular conditions. However, additionalstudies are required to standardize saliva collection and storage procedures, validate analytical techniques for biomarker detection, and establish reference ranges for routine clinical use. The purpose of this review is to summarize and evaluate recent advancements in using saliva as a diagnostic tool for inflammation and insulinresistance.

Effect of Saliva Contamination on Shear Bond Strength of Orthodontic Brackets When Using a Self-Etch Primer

The effect of saliva contamination on the shear bond strength of orthodontic brackets, at various stages of the bonding procedure using a new self-etch primer was studied. The samples were divided into 4 groups according to 4 different enamel surface conditions: Group A: dry; Group B: saliva contamination before priming; Group C: saliva contamination after priming, and Group D: saliva contamination before and after priming. Stainless steel brackets were bonded in each test group with a light-cured composite resin (TransbondXT 3M). The shear bond strength was determined in the first 30 min after bonding. The analysis of variance indicated that the shear bond strengths of the 4 groups were significantly different (F=11.89, P<0.05). Tukey HSD tests indicated that contamination both before and after the application of the acid-etch primer resulted in a significantly lower (=4.6±1.7 MPa) shear bond strength than either the control group (=8.8±1.9 MPa) or the groups where contamination occurred either before (=7.9±2.0 MPa) or after (=6.9±1.5 MPa) the application of the primer. It was concluded that the new acid-etch primer could maintain adequate shear bond strength if contamination occurred either before or after the application of the primer. On the other hand, contamination both before and after the application of the primer could significantly reduce the shear bond strength of orthodontic brackets.

Inflammation-related gene expression profiles of salivary extracellular vesicles in patients with head trauma

At present,there is no reliable biomarker for the diagnosis of traumatic brain injury(TBI).Studies have shown that extracellular vesicles released by damaged cells into biological fluids can be used as potential biomarkers for diagnosis of TBI and evaluation of TBI severity.We hypothesize that the genetic profile of salivary extracellular vesicles in patients with head trauma differs from that in uninjured subjects.Findings from this hypothesis would help investigate the severity of TBI.This study included 19 subjects,consisting of seven healthy controls who denied history of head trauma,six patients diagnosed with concussion injury from an outpatient concussion clinic,and six patients with TBI who received treatment in the emergency department within 24 hours after injury.Real-time PCR analysis of salivary extracellular vesicles in participants was performed using TaqMan Human Inflammation array.Gene expression analysis revealed nine upregulated genes in emergency department patients(LOX5,ANXA3,CASP1,IL2RG,ITGAM,ITGB2,LTA4H,MAPK14,and TNFRSF1A)and 13 upregulated genes in concussion clinic patients compared with healthy participants(ADRB1,ADRB2,BDKRB1,HRH1,HRH2,LTB4R2,LTB4R,PTAFR,CYSLTR1,CES1,KLK1,MC2R,and PTGER3).Each patient group had a unique profile.Comparison between groups showed that 15 inflammation-related genes had significant expression change.Our results indicate that inflammation biomarkers can be used for diagnosis of TBI and evaluation of disease severity.This study was approved by the Institutional Review Board on December 18,2015(approval No.0078-12)and on June 9,2016(approval No.4093-16).

Prevalence of Enterococcus faecalis in saliva and filled root canals of teeth associated with apical periodontitis

To investigate the prevalence of Enterococcus faecalis in saliva and filled root canals of patients requiring endodontic retreatment for apical periodontitis.Patients with apical periodontitis who were referred for endodontic retreatment were examined.The type and quality of the restoration,symptoms,quality of obturation were recorded.During retreatment,an oral rinse sample and root canal sample were cultured using brain-heart infusion agar and bile esculinazide agar to select for E.faecalis.The 16S rRNA technique was used to identify E.faecalis.A total of 32 women and 22 men（mean age：38 years;s.d.：11 years） and 58 teeth were studied.The prevalence of E.faecalis was 19% in the saliva and 38% in the root canals.The odds that root canals harbored E.faecalis were increased if the saliva habored this bacterium（odds ratio59.7;95% confidence interval51.8-51.6;P,0.05）.Teeth with unsatisfactory root obturation had more cultivable bacterial species in root canals than teeth with satisfactory root obturation（P,0.05）.E.faecalis is more common in root canals of teeth with apical periodontitis than in saliva.The prevalence of E.faecalis in root canals is associated with the presence of E.faecalis in saliva.