The effects of storage time and temperature on the stability of salivary phosphatases, transaminases and dehydrogenase

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

BACKGROUND

Human saliva as a bodily fluid-similar to blood-is utilized for diagnostic purposes. Unlike blood sampling, collecting saliva is non-invasive, inexpensive, and readily accessible. There are no previously published systematic reviews regarding different collection, transportation, preparation, and storage methods for human saliva.

DESIGN

This study has been prepared and organized according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) 2020 guidelines. This systematic review has been registered at PROSPERO (Registration ID: CRD42023415384). The study question according to the PICO format was as followed: Comparison of the performance (C) of different saliva sampling, handling, transportation, and storage techniques and methods (I) assessed for analyzing stimulated or unstimulated human saliva (P and O). An electronic search was executed in Scopus, Google Scholar, and PubMed.

RESULTS

Twenty-three descriptive human clinical studies published between 1995 and 2022 were included. Eight categories of salivary features and biomarkers were investigated (i.e., salivary flow rate, total saliva quantity, total protein, cortisol, testosterone, DNA quality and quantity, pH and buffering pH). Twenty-two saliva sampling methods/devices were utilized. Passive drooling, Salivette®, and spitting were the most utilized methods. Sampling times with optimum capabilities for cortisol, iodine, and oral cancer metabolites are suggested to be 7:30 AM to 9:00 AM, 10:30 AM to 11:00 AM, and 14:00 PM to 20:00 PM, respectively. There were 6 storage methods. Centrifuging samples and storing them at -70 °C to -80 °C was the most utilized storage method. For DNA quantity and quality, analyzing samples immediately after collection without centrifuging or storage, outperformed centrifuging samples and storing them at -70 °C to -80 °C. Non-coated Salivette® was the most successful method/device for analyzing salivary flow rate.

CONCLUSION

It is highly suggested that scientists take aid from the reported categorized outcomes, and design their study questions based on the current voids for each method/device.

Enzyme activity, DNA degradation and drying times of semen, saliva and vaginal material

The stability of enzyme activity and the amount of detectable DNA within liquid samples of semen, saliva and vaginal material were tested across a number of days. The concentration of DNA within neat semen and saliva samples fell significantly after one week of refrigeration. No apparent change in acid phosphatase or amylase enzyme activity was observed in neat semen and saliva samples over 96 or 72 h respectively. Changes in the enzyme activity of most of the dilute semen and saliva samples, as well as the neat vaginal material sample, were noted after 24 h. The drying times and sizes of stains produced from various volumes of neat semen, saliva and vaginal material were tested on porous and non-porous surfaces at room temperature. Larger volumes of body fluid took longer to dry and generally resulted in larger stains. Body fluids on a non-porous surface took longer to dry than on the porous surface tested.

Current Status and Future Perspectives of Lactate Dehydrogenase Detection and Medical Implications: A Review

The demand for glucose uptake and the accompanying enhanced glycolytic energy metabolism is one of the most important features of cancer cells. Unlike the aerobic metabolic pathway in normal cells, the large amount of pyruvate produced by the dramatic increase of glycolysis in cancer cells needs to be converted to lactate in the cytoplasm, which cannot be done without a large amount of lactate dehydrogenase (LDH). This explains why elevated serum LDH concentrations are usually seen in cancer patient populations. LDH not only correlates with clinical prognostic survival indicators, but also guides subsequent drug therapy. Besides their role in cancers, LDH is also a biomarker for malaria and other diseases. Therefore, it is urgent to develop methods for sensitive and convenient LDH detection. Here, this review systematically summarizes the clinical impact of lactate dehydrogenase detection and principles for LDH detection. The advantages as well as limitations of different detection methods and the future trends for LDH detection were also discussed.

Saliva nitrite is higher in male children with autism spectrum disorder and positively correlated with serum nitrate

Objectives

Nitric oxide (NO) plays a vital role in neurological development. As an easily accessible and non-invasive fluid, saliva hasn't been evaluated for nitrite among children with autism spectrum disorder (ASD). This study aims to quantify saliva nitrite and explore its relation with serum NO.

Methods

Saliva sampling and pretreatment methods were optimized, followed by NO measurement via chemiluminescence for 126 ASD children and 129 normally developing children (ND).

Results

In the ASD group, saliva nitrite was significantly higher than that in the ND, with concentrations of 4.97 ± 3.77 μM and 2.66 ± 2.07 μM (p < 0.0001), respectively. Positive correlation was observed between saliva NO₂⁻ and serum NO₃⁻ in ASD children, which didn't exist in the ND group. Male children in the ASD group had significantly higher NO than that in boys of the ND group, without significant difference between girls in both groups. Correlation was not found between saliva or serum NO and severity of these ASD children.

Discussion

It is reported for the first time that saliva nitrite was positively correlated with serum nitrate in ASD children, with significantly higher NO only in autistic boys. Non-invasive saliva might serve as a predictor of health status of ASD children.

Analysis of Saliva Lipids in Breast and Prostate Cancer by IR Spectroscopy

We have developed a method for studying the lipid profile of saliva, combining preliminary extraction and IR spectroscopic detection. The case-control study involved patients with a histologically verified diagnosis of breast and prostate cancer and healthy volunteers. The comparison group included patients with non-malignant pathologies of the breast (fibroadenomas) and prostate gland (prostatic intraepithelial neoplasia). Saliva was used as a material for biochemical studies. It has been shown that the lipid profile of saliva depends on gender, and for males it also depends on the age group. In cancer pathologies, the lipid profile changes significantly and also depends on gender and age characteristics. The ratio of 1458/1396 cm-1 for both breast and prostate cancer has a potential diagnostic value. In both cases, this ratio decreases compared to healthy controls. For prostate cancer, the ratio of 2923/2957 cm-1 is also potentially informative, which grows against the background of prostate pathologies. It is noted that, in all cases, changes in the proposed ratios are more pronounced in the early stages of diseases, which increases the relevance of their study in biomedical applications.

The effects of a novel herbal toothpaste on salivary lactate dehydrogenase as a measure of cellular integrity

OBJECTIVE

Lactate dehydrogenase (LDH) is a critical intracellular enzyme responsible for anaerobic respiration in pyruvate metabolism which becomes detectable in extracellular spaces after cellular breakdown. This clinical investigation examined the effects of brushing with a test toothpaste containing natural ingredients, i.e., clove (Syzygium aromaticum), aloe vera (Aloe barbadensis), amla (Emblica officinalis), neem (Azadirachta indica), tulsi (Ocimum basillicum), and honey (from Apis mellifera), and 0.96% zinc (zinc oxide, zinc citrate) and 0.76% SMFP (1000 ppm F) in a calcium carbonate base formulated with natural ingredients (Ved Shakti, Colgate Palmolive India) and a fluoride toothpaste containing 0.76% SMFP (1000 ppm F) in a calcium carbonate base (Colgate Cavity Protection, Colgate Palmolive; henceforth control) on salivary LDH in conjunction with the assessments of dental plaque and gingivitis representing oral hygiene parameters.

MATERIALS AND METHODS

This double-blind, two-cell study enrolled 70 adults (age range 20-59 years). Subjects completed a washout and provided baseline saliva samples for LDH analysis and clinical assessments of dental plaque and gingivitis using the Turesky Modification of Quigley-Hein and Loe-Silness methods respectively. Subjects were randomly assigned to brush their teeth with either the test or control. Post-treatment sample collection and clinical evaluations were conducted after 3 weeks, 6 weeks, and 12 week sof brushing with all assessments conducted 12 h after hygiene. Statistical analyses were conducted independently for each parameter by t-test for within treatment evaluation and analysis of covariance (ANCOVA) for between treatment comparisons.

RESULTS

At baseline, treatment groups demonstrated no significant differences for LDH or dental plaque and gingival index scores. Brushing with the test demonstrated progressive reductions in salivary LDH, plaque and gingival index scores over the study duration in comparison to the control. The test demonstrated reductions in LDH of 9.5-15.4% over the study period in comparison to the control representing statistically significant effects (p < 0.05). The test also demonstrated reductions in dental plaque that ranged between 6.4 and 16.2% over the study period and gingivitis reductions that ranged between 8.2 and 23.8% representing statistically significant results (p < 0.05).

CONCLUSIONS

Brushing with a novel herbal toothpaste demonstrated significant reductions in salivary LDH representing improvements in cellular integrity with concurrent reductions in dental plaque and gingivitis as compared to the control dentifrice.

CLINICAL RELEVANCE

Salivary LDH measurements offer a non-invasive and objective measurement of mucosal cellular integrity complementing other evaluations and clinical assessments such as plaque and gingival index scores.

Gender influence on antioxidant capacity and oxidative damage in saliva of children with autism spectrum disorder: a preliminary study

Abstract Introduction Autism is a complex neurological disorder with multifactorial causes, which compromises physical, psychological, emotional and social skills. This disorder also impairs dental care and patient oral health. Saliva can be easily obtained using a non-invasive technique and has been used in the diagnosis and screening of many pathologies. Total antioxidant capacity of saliva is reduced in the presence of caries in children and has been studied as a possible marker for autism. However, data on salivary antioxidants in children with autism spectrum disorder (ASD) is scarce. Objective This preliminary study evaluated the existence of gender influence on non-enzymatic antioxidant capacity and protein oxidative damage in the saliva of children with this disorder. Our hypothesis is that there are gender differences in these biochemical parameters in children with austim. Material and method Whole saliva samples were collected by aspiration between 8:00-11:00 am from 12 girls and 12 boys aged 5 to 15 years, with previous diagnosis for this disorder. Total antioxidant capacity, uric acid, protein concentration and oxidative damage to proteins were analyzed by spectrophotometry. Values were presented as mean ± standard deviation and tested for adherence to normality (Shapiro-Wilk test). The data were then compared using the Mann-Whitney test, considering a 5% significance level. Result There was no significant difference between groups for all analyzed parameters (P>0.05). Conclusion Based on the results obtained, we concluded that gender does not influence the levels of oxidative stress markers in the saliva of children with ASD.

Evaluation of Saliva Stability for NMR Metabolomics: Collection and Handling Protocols

Maintaining a salivary metabolic profile upon sample collection and preparation is determinant in metabolomics. Nuclear magnetic resonance (NMR) spectroscopy was used to identify metabolite changes during short-term storage, at room temperature (RT)/4 °C/-20 °C, and after sample preparation, at RT/4 °C (mimicking typical clinical/laboratory settings). Interestingly, significant metabolic inter-individual and inter-day variability were noted, probably determining sample stability to some extent. After collection, no changes were noted at -20 °C (at least for 4 weeks). RT storage induced decreases in methylated macromolecules (6 h); lactate (8 h); alanine (12 h); galactose, hypoxanthine, pyruvate (24 h); sarcosine, betaine, choline, N-acetyl-glycoproteins (48 h), while acetate increased (48 h). Less, but different, changes were observed at 4 °C, suggesting different oral and microbial status at different temperatures (with a possible contribution from inter-individual and inter-day variability), and identifying galactose, hypoxanthine, and possibly, choline esters, as potential general stability indicators. After preparation, addition of NaN3 did not impact significantly on saliva stabilization, neither at RT nor at 4 °C, although its absence was accompanied by slight increases in fucose (6.5 h) and proline (8 h) at RT, and in xylose (24 h) at 4 °C. The putative metabolic origins of the above variations are discussed, with basis on the salivary microbiome. In summary, after collection, saliva can be stored at RT/4 °C for up to 6 h and at -20 °C for at least 4 weeks. Upon preparation for NMR analysis, samples are highly stable at 25 °C up to 8 h and at 4 °C up to 48 h, with NaN3 addition preventing possible early changes in fucose, proline (6-8 h), and xylose (24 h) levels.

Sputum and salivary protein biomarkers and point-of-care biosensors for the management of COPD

Chronic obstructive pulmonary disease (COPD) has become one of the most fatal diseases of the century considering mortality and morbidity levels worldwide. This disease is an inflammatory response to environmental stress and tobacco smoking. Although spirometry is the gold-standard diagnostic test administrated in primary and secondary care, it often exhibits low accuracy in cases of predicting disease worsening and possible bias due to the operator, patient, and conditions. Recent developments in proteomics research suggest that the presence of protein biomarkers can aid in the accurate diagnosis and prediction of disease outcomes. This review presents the cutting-edge research progress in the area of protein biomarkers towards the management of COPD. The literature review was confined to protein biomarkers in saliva and sputum because testing these bodily fluids shows great promise for point-of-care (POC) testing due to its practicality, non-invasiveness and inexpensive handling and sampling. Although it is conclusive that more studies on sputum and saliva are needed, this review studies the promising clinical value of interleukin (IL)-6 and IL-8, matrix metalloproteinase (MMP)-8 and MMP-9, C-reactive protein (CRP), tumor necrosis factor-alpha (TNF-α), and neutrophil elastase (NE). Following the critical analysis of salivary and sputum biomarkers, the recent development of POC biosensors for the multiplexed detection of biomarkers is also reported. Overall, the review aims to explore the possibility for the future development of POC sensors for chronic lung disease management utilizing clinically relevant biomarkers in saliva and sputum.

Peptide Bond Formation Between the Hetrosubunits of ω-Transaminase, Alanine Dehydrogenase, and Formate Dehydrogenase Through Subunit Splicing Promoted by Heterodimerization of Leucine Zipper Motifs

For the multimeric enzymes R-ω-transaminase (RTA), alanine dehydrogenase (AlaDH), and formate dehydrogenase (FDH), peptide bond formation between the hetrosubunits has been achieved by the intein-mediated in vivo subunit splicing. The subunit ligation is triggered by the heterodimerization of an arginine rich leucine zipper motif with a glutamic acid rich leucine zipper motif. The one-by-one ligation of hetrosubunits constructs the pairing enzymes RTA&AlaDH and AlaDH&FDH. The ligation modes were analyzed based on blue native polyacrylamide gel electrophoresis (BN-PAGE). The spectra of circular dichroism (CD), fluorescence, and two-dimensional FTIR provide information on the secondary structures and stability of the pairing enzymes. The enzyme-substrate interaction was analyzed based on microscale thermophoresis analysis. In contrast to the mixed three enzymes RTA + AlaDH + FDH, the ligated enzymes RTA&AlaDH + AlaDH&FDH exhibited a much larger substrate affinity, higher stability, and significantly enhanced activity.

Identification of salivary volatile organic compounds as potential markers of stomach and colorectal cancer: A pilot study

OBJECTIVES

The purpose of the pilot study was to determine the potential diagnostic capabilities for the analysis of oxygen-containing salivary volatile organic compounds (VOCs) in stomach and colorectal cancer.

METHODS

Saliva samples of 11 patients with stomach cancer, 18 patients with colorectal cancer, and 16 healthy volunteers were analyzed through capillary gas chromatography. The levels of lipid peroxidation products and catalase activity were determined in all samples. To assess saliva diagnostic potential, we constructed a Classification and Regression Tree (CART).

RESULTS

It was shown that the use of a combination of saliva VOCs (acetaldehyde, acetone, propanol-2, and ethanol) allowed classification into Cancer/Control groups with a sensitivity and specificity of 95.7 and 90.9%, respectively. To clarify the location of the tumor, it was necessary to add a methanol level; in this case, the sensitivity for detecting stomach and colorectal cancer was 80.0% and 92.3%, respectively, while the specificity in both cases was 100%. When the lipid peroxidation product content was added to the VOC indicators, they were selected as the main factors for constructing the decision tree. For classification into Cancer/Control groups, only the triene conjugate and Schiff base content in saliva was sufficient. The combination of VOCs in saliva and lipid peroxidation indices improved the sensitivity and specificity for classification to 100%.

CONCLUSION

Preliminary data were obtained on the sensitivity and specificity of the diagnosis of stomach and colorectal cancer, which confirmed the promise of further studies on saliva VOCs for the purpose of clinical laboratory diagnostics.

Age and Gender Characteristics of the Infrared Spectra of Normal Human Saliva

The comparison of the characteristics of the infrared (IR) spectra of saliva of healthy volunteers was carried out based on gender and age. It is shown that statistically significant differences between male and female groups are observed for the absorption bands of proteins and lipids. At the same time, the absorbance of the bands assigned to proteins and nucleic acids is higher for males, whereas the absorbance of the bands assigned to lipids is higher in the group of females. It is established that the correlation relationships of the characteristics of the spectra and age are weakly expressed. Thus, when forming the criteria of the norm and pathology for saliva, it is necessary to take into account the gender of the subjects, while there are no strict requirements for taking into account age periodization. Nevertheless, the revealed patterns are valid only for the composition of the saliva of healthy volunteers, the extension of the results to groups of patients with various diseases, as well as other biological fluids, requires additional testing.

Biochemical Markers of Saliva in Lung Cancer: Diagnostic and Prognostic Perspectives

The aim of the work is to study the metabolic characteristics of saliva in lung cancer for use in early diagnosis and determining the prognosis of the disease. The patient group included 425 lung cancer patients, 168 patients with non-cancerous lung diseases, and 550 healthy volunteers. Saliva samples were collected from all participants in the experiment before treatment and 34 biochemical saliva parameters were determined. Participants were monitored for six years to assess survival rates. The statistical analysis was performed by means of Statistica 10.0 (StatSoft) program and R package (version 3.2.3). To construct the classifier, the Random Forest method was used; the classification quality was assessed using the cross-validation method. Prognostic factors were analyzed by multivariate analysis using Cox's proportional hazard model in a backward step-wise fashion to adjust for potential confounding factors. A complex of metabolic changes occurring in saliva in lung cancer is described. Seven biochemical parameters were identified (catalase, triene conjugates, Schiff bases, pH, sialic acids, alkaline phosphatase, chlorides), which were used to construct the classifier. The sensitivity and specificity of the method were 69.5% and 87.5%, which is practically not inferior to the diagnostic characteristics of markers routinely used in the diagnosis of lung cancer. Significant independent factors in the poor prognosis of lung cancer are imidazole compounds (ICs) above 0.478 mmol/L and salivary lactate dehydrogenase activity below 545 U/L. Saliva has been shown to have great potential for the development of diagnostic and prognostic tests for lung cancer.

Age and gender characteristics of the biochemical composition of saliva: Correlations with the composition of blood plasma

Background

Recently, the attention of researchers to the study of the properties of human saliva, as a material with unique properties and diagnostic capabilities, has increased.

Research objective

to study the connection of the biochemical composition of saliva and blood plasma in the norm, depending on gender and age.

Methods

107 volunteers took part in the study, including 46 female (37.2 ± 3.9 years old) and 61 male (36.1 ± 2.8 years old). In all samples of saliva and blood plasma, 16 biochemical parameters were determined, including mineral and protein composition, enzyme activity. Non-parametric statistical methods were used to process the data.

Results

It has been shown that it is difficult to establish an unambiguous relation between biochemical parameters of saliva and blood plasma. The calculation of the Spearman correlation coefficients showed that only 7 of the 16 parameters demonstrate the presence of a weak correlation between the content in saliva and plasma.

Conclusion

In general, the determination of the composition of saliva may have an independent diagnostic value; in this case, drawing a parallel with the composition of serum and blood plasma is not advisable. Nevertheless, the use of saliva in clinical laboratory diagnostics is associated with the need to establish criteria for the norm and pathology for each biochemical parameter.

Periodontal condition, changes in salivary biochemical parameters, and oral health-related quality of life in patients with anorexia and bulimia nervosa

BACKGROUND

Anorexia and bulimia nervosa can have significant effects on oral health. Assessment of enzyme concentrations in saliva can be useful for obtaining information on molecular biomarkers for the prevention, monitoring, and diagnosis of oral diseases. This study investigated the periodontal condition, changes in salivary biochemical parameters, and oral health-related quality of life (OHRQoL) in patients with anorexia and bulimia nervosa.

METHODS

The study comprised 60 women patients who attended a Brazilian medical school. Participants were divided into two groups: patients with anorexia and bulimia nervosa (ABN; n = 30) and control patients (CN; n = 30). Oral clinical examinations were carried out to evaluate the periodontal condition by Community Periodontal Index, and interviews using the Oral Health Impact Profile (OHIP-14) were conducted to assess OHRQoL. Saliva samples were collected for the evaluation of salivary concentrations of total protein, alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and thiobarbituric acid reactive substance (TBARS), and salivary flow rate.

RESULTS

Periodontal condition in the ABN group was significantly worse than that in the CN group. The ABN group showed significantly higher salivary concentrations of total protein, AST, ALT, and LDH than the CN group. There was no significant difference in the salivary concentrations of TBARS among the groups. The OHIP-14 score was higher in the ABN group than in the CN group.

CONCLUSION

Anorexia and bulimia nervosa are associated with poor periodontal condition, elevated salivary concentrations of total protein, AST, ALT, and LDH, decreased salivary flow rate and a significant adverse impact on OHRQoL.

Morphology of Dried Drop Patterns of Saliva from a Healthy Individual Depending on the Dynamics of Its Surface Tension

Background: The study of processes in the drying drops of biological fluids (dried drop patterns) and the method of dynamic surface tensiometry can be attributed to integral methods of assessing the state of the organism. Research objective: to establish the relationship between the type of crystallization patterns and the surface tension of human saliva in normal conditions. Methods: 100 volunteers (40 males, 60 females) that were aged 30–59 participated in the study. In all saliva samples, the parameters of dynamic tensiometry, types of crystallization patterns and 11 biochemical parameters were determined. Results: No statistically significant differences in the saliva crystallization patterns were observed, depending on the age and gender characteristics of the volunteers. A negative correlation of the area of the crystallization zone and the surface tension of saliva is shown. When considering the crystallization patterns, their considerable variability was noted; on this basis, the entire studied sample was divided into four clusters by surface tension. Conclusion: In general, the crystallization patterns that are inside the selected groups remain quite heterogeneous. This increases the likelihood of making an incorrect diagnosis when using visual methods to evaluate the crystallization patterns, which significantly limits the use of such diagnostic methods in clinical practice.

Changes of salivary biomarkers under different storage conditions: effects of temperature and length of storage

Introduction

In this report, we aimed to examine the stability of various analytes in saliva under different storage conditions.

Materials and methods

Alpha-amylase (AMY), cholinesterase (CHE), lipase (Lip), total esterase (TEA), creatine kinase (CK), aspartate aminotransferase (AST), lactate dehydrogenase (LD), lactate (Lact), adenosine deaminase (ADA), Trolox equivalent antioxidant capacity (TEAC), ferric reducing ability (FRAS), cupric reducing antioxidant capacity (CUPRAC), uric acid (UA), catalase (CAT), advanced oxidation protein products (AOPP) and hydrogen peroxide (H₂O₂) were colorimetrically measured in saliva obtained by passive drool from 12 healthy voluntary donors at baseline and after 3, 6, 24, 72 hours, 7 and 14 days at room temperature (RT) and 4 ºC, and after 14 days, 1, 3 and 6 months at – 20 ºC and – 80 ºC.

Results

At RT, changes appeared at 6 hours for TEA and H₂O₂; 24 hours for Lip, CK, ADA and CUPRAC; and 72 hours for LD, Lact, FRAS, UA and AOPP. At 4 ºC changes were observed after 6 hours for TEA and H₂O₂; 24 hours for Lip and CUPRAC; 72 hours for CK; and 7 days for LD, FRAS and UA. At – 20 ºC changes appeared after 14 days for AST, Lip, CK and LD; and 3 months for TEA and H₂O₂. At – 80 ºC observed changes were after 3 months for TEA and H₂O₂.

Conclusions

In short-term storage, the analytes were more stable at 4 ºC than at room temperature, whereas in long-term storage they were more stable at - 80 ºC than at – 20 ºC.

Stability of selected enzymes in saliva of pigs under different storage conditions: a pilot study

Stability of α-amylase (α-A), butyrylcholinesterase (BChE), lipase, adenosine deaminase (ADA) and total esterase activity (TEA) in two pools of porcine saliva was studied after 1 and 4 days at 4°C, and after 30, 90 and 360 days at -20° and -80°C. At 4°C, BChE, lipase and TEA were stable less than 1 day, α-A less than 4 days and ADA for up to 4 days. At -20°C, BChE and TEA were stable less than 30 days, α-A and lipase less than 90 days and ADA up to 360 days. At -80°C, TEA was stable less than 30 days, α-A and lipase less than 360 days, and BChE and ADA for up to 360 days.