Rapid saliva processing techniques for near real-time analysis of salivary steroids and protein

Optimization of saliva sampling methods for analysis of bile acids by UHPLC-MS

This study investigated methods for sampling bile acids in saliva, a potential non-invasive diagnostic biofluid. Bile acids have been implicated in causing damage and permanent changes to the esophageal mucosa and increasing the risk of developing Barrett's esophagus, a condition that can potentially progress to esophageal cancer. Three saliva collection methods were compared: spitting, Salivette® swabs, and Salivette Cortisol® swabs. Spitting emerged as the superior method with the highest recoveries and the least interference, likely due to Salivette swabs retaining bile acids or introducing unknown interferences. All saliva samples were analyzed by UHPLC-MS/MS using the Zorbax RRHD Eclipse Plus C18 column (3 × 50 mm, 1.8 µm) in gradient elution of 0.1 % formic acid in water and methanol. Saliva sample stability was assessed over 14 days, reflecting typical storage times. The levels of detected bile acids were stable for the measured period (RSD ≤ 22 %) and no degradation was observed. Bile acid levels in saliva fluctuated throughout the day, with the greatest changes observed for glycine-conjugated bile acids after meals. To minimize sampling variability, saliva collection by spitting after overnight fasting is recommended for future studies. Our findings are applicable for standardized bile acid sampling and are currently applied in a large clinical study evaluating bile acids as potential susceptibility markers for Barrett's esophagus diagnostics.

Effects of filtration and alpha-amylase depletion on salivary biochemical composition measurements

The effects of filtration (F) and alpha-amylase depletion (AD) were assessed in n = 34 saliva samples. Each saliva sample was split into three aliquots and treated as follows: (1) no treatment; (2) 0.45μm commercial filter; and (3) 0.45μm commercial filter and affinity depletion of alpha-amylase. Then, a panel of biochemical biomarkers consisting of amylase, lipase, alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), creatine kinase (CK), calcium, phosphorus, total protein, albumin, urea, creatinine, cholesterol, triglycerides, and uric acid was measured. Differences between the different aliquots were observed in all measured analytes. The most marked changes were found in triglycerides and lipase data for filtered samples, and in alpha-amylase, uric acid, triglycerides, creatinine, and calcium results in alpha-amylase-depleted aliquots. In conclusion, the salivary filtration and amylase depletion methods employed in this report caused significant changes in saliva composition measurements. Based on these results, it would be recommended to consider the possible effects of these treatments in salivary biomarkers when filtration or amylase depletion is performed.

Pretreatment Methods for Human Nasopharyngeal Swabs to Increase the Signal to Noise Ratio of High Sensitivity Immunoassays

Mucous samples collected through nasopharyngeal (NP) swabs are considered gold standard specimens for the detection of respiratory pathogens. Matrices of these highly viscous samples often cause significant background noises in immunoassays, especially immunoassays with high sensitivity. We demonstrated such nonspecific background signals in both a chemiluminescence enzyme-linked immunosorbent assay (ELISA) and a novel highly sensitive immunoassay called Microbubbling SARS-CoV-2 Antigen Assay (MSAA). We developed and demonstrated the effectiveness of two quick sample pretreatment methods, filtration and preadsorption, to decrease nonspecific signals and increase the signal-to-noise ratio (SNR). Using these pretreatment methods, the SNR (at 3.6 × 10⁴ copies/mL of inactivated SARS-CoV-2) was increased by 42.4-fold (95% CI 41.0-43.8) and 67.1-fold (95% CI 57.9-76.3) in the MSAA, and 1.3-fold (95% CI 0.9-1.7) and 1.8-fold (95% CI 1.6-2.0) in the chemiluminescence ELISA assay. Sample pretreatment methods developed in this study are broadly adaptable for the development of immunoassays for highly viscous samples.

Unstimulated Parotid Saliva Is a Better Method for Blood Glucose Prediction

Objective: Saliva glucose has been widely used in diagnosing and monitoring diabetes, but the saliva collection method will affect saliva glucose concentration. So, this study aims to identify the ideal saliva collection method. Method: A total amount of six saliva collection methods were employed in 80 healthy participants in the morning. Besides, three unstimulated saliva methods were employed in another 30 healthy participants in the morning; in the meantime the blood glucose of these 30 participants was detected with a Roche blood glucose meter. The glucose oxidase method with 2, 4, 6-tribromo-3-hydroxybenzoic acid (TBHBA) as the chromogen has been improved to be suitable for healthy people, through the selection of the optimal pH value and ionic strength of the reaction system. This method was used for the detection of saliva glucose. Results: The improved method obtained absorbance at the wavelength of 520 nm, and the optimized parameter combination was pH 6.5 and 5 mg/dL NaCl. The lower limit of glucose detection was 0.1 mg/dL. Unstimulated saliva glucose concentration was higher than stimulated saliva glucose concentration. Unstimulated parotid saliva glucose concentration was the highest. Besides, unstimulated saliva glucose has a better normal distribution effect. Meantime, it was found that unstimulated parotid saliva was the most highly correlated with blood glucose (R2 = 0.707). Conclusions: the saliva collection method was an important factor that affected saliva glucose concentration. Unstimulated parotid saliva was the most highly correlated with blood glucose, which provided a reference for prediction of diabetes mellitus.

Effect of collection material and sample processing on pig oral fluid testing results

The effect of sampling material, sample processing, and collection order on the detection of analytes in pig oral fluid specimens was evaluated. Oral fluid samples were collected from 104 pens of commercial wean-to-finish pigs using ropes made of three different materials. Processed (centrifuged and filtered) and unprocessed oral fluid samples were tested using commercial ELISAs for porcine reproductive and respiratory syndrome virus (PRRSV) antibodies and total IgM, IgA, and IgG. Unprocessed samples were tested for PRRSV nucleic acid and processed samples were assayed for PRRSV neutralizing antibodies. Analysis of the data using repeated measures ANOVA and Tukey-Kramer adjusted t tests found statistically significant, non-uniform, and assay-dependent effects of all three factors. Therefore, when testing oral fluid specimens, swine health specialists, veterinarians, and diagnosticians should be aware of the potential impact of these factors on specific analytes. For monitoring health and welfare parameters, oral fluid samples should be collected using cotton-based materials and undergo minimal post-collection processing.

Controlling sources of preanalytical variability in doping samples: challenges and solutions

The use of illicit substances and methods contravenes the ethics of sports and may be associated with side effects. Antidoping testing is an essential tool for preventing or limiting the consequences of cheating in sports. As for conventional laboratory testing, major emphasis has been placed on analytical quality, overlooking the inherent risks that may arise from analysis of unsuitable doping samples. The adherence to scrupulous criteria for collection, handling, transportation and storage of samples, especially blood and urine samples, is essential. The leading preanalytical variables that influence doping sample quality include biological variability, sample collection, venous stasis, spurious hemolysis and presence of other interfering substances, sample manipulation and degradation, and inappropriate conditions for transportation and storage. This article provides a personal overview about the current challenges in preanalytical management of doping samples, as well as potential solutions for preventing the negative impact of preanalytical variables on sample quality and test results.

Real-time clinical monitoring of biomolecules

Continuous monitoring of clinical biomarkers offers the exciting possibility of new therapies that use biomarker levels to guide treatment in real time. This review explores recent progress toward this goal. We initially consider measurements in body fluids by a range of analytical methods. We then discuss direct tissue measurements performed by implanted sensors; sampling techniques, including microdialysis and ultrafiltration; and noninvasive methods. A future directions section considers analytical methods at the cusp of clinical use.

Measurement of salivary cortisol in 2012 - laboratory techniques and clinical indications

The utility of measuring salivary cortisol has become increasingly appreciated since the early 1980s. Salivary cortisol is a measure of active free cortisol and follows the diurnal rhythm of serum or plasma cortisol. The saliva sample may be collected by drooling or through the use of absorbent swabs which are placed into the mouth until saturated. Salivary cortisol is therefore convenient for patients and research participants to collect noninvasively on an outpatient basis. Several assay techniques have been used to measure salivary cortisol, including radioimmunoassay and more recently liquid chromatography-tandem mass spectrometry. The analytical sensitivity varies between these assay methods, as does the potential for cross-reactivity with other steroids. The interpretation of salivary cortisol levels relies on rigorous standardization of sampling equipment, sampling protocols and assay technology with establishment of a local reference range. Clinically, the commonest use for salivary cortisol is measuring late-night salivary cortisol as a screening test for Cushing's syndrome. Several studies have shown diagnostic sensitivities and specificities of over 90%, which compares very favourably with other screening tests for Cushing's syndrome such as the 24-h urinary-free cortisol and the 1-mg overnight dexamethasone suppression test. There are emerging roles for the use of salivary cortisol in diagnosing adrenal insufficiency, particularly in conditions associated with low cortisol-binding globulin levels, and in the monitoring of glucocorticoid replacement. Finally, salivary cortisol has been used extensively as a biomarker of stress in a research setting, especially in studies examining psychological stress with repeated measurements.

Development of an Au/ZnO thin film surface plasmon resonance-based biosensor immunoassay for the detection of carbohydrate antigen 15-3 in human saliva

OBJECTIVE

To evaluate a novel surface plasmon resonance (SPR) system for the direct measurement of tumor marker carbohydrate antigen 15-3 (CA15-3) in human saliva.

DESIGN AND METHODS

We measured the presence of the tumor marker carbohydrate antigen 15-3 (CA15-3) in human saliva using 2 different surface plasmon resonance (SPR) systems. To compare the sensitivity of an SPR biosensor based on thin-film Au/ZnO and the Biacore SPR system, we prepared CA15-3 samples in saliva and analyzed intensity responses to the samples at various concentrations of CA15-3.

RESULTS

The linear detection range of CA15-3 in human saliva with the SPR system based on thin-film Au/ZnO was 2.5-20 U/mL (the cut-off point in cancer patients is around 4 U/mL). The linear range with the Biacore SPR system was 40-300 U/mL.

CONCLUSIONS

These results show that thin-film Au/ZnO-based SPR systems have higher sensitivity and can be used for measuring the levels of CA15-3 in human saliva without concentrating the samples.

Individual exercise sessions alter circulating hormones and cytokines in HIV-infected men

Exercise has the potential to impact disease by altering circulating anabolic and catabolic factors. It was the goal of this study to determine how different regimens of low-intensity and moderate-intensity exercise affected circulating levels of these anabolic and catabolic factors in HIV-infected men. Exercise-naive, HIV-infected men, medically cleared for study participation, were randomized into one of the following groups: a moderate-intensity group (MOD, who completed 30 min of moderate-intensity aerobic training followed by 30 min of moderate-intensity resistance training; a low-intensity group (LOW), who completed 60 min of treadmill walking; or a control group (CON), who attended the clinic but participated in no activity. Blood and saliva samples were collected at selected time points before, during, and after each of the 3 required sessions. Compared with baseline, the MOD group (n=14) had a 135% increase in growth hormone (GH) (p<0.05) and a 34% decrease in cortisol (CORT) (p<0.05) at the post time point, a 31% increase in interleukin-6 (IL-6) (p<0.05) at 30-min post exercise, and a 23% increase in IL-6 (p<0.05) and a 13% decrease in soluble tumor necrosis factor receptor 2 (sTNFrII) (p<0.05) at 60-min post exercise. The LOW (n=11) group had a 3.5% decrease in sTNFrII (<0.05) at 30-min post exercise compared with baseline and a 49% decrease (p<0.05) in GH at 60-min post exercise. The CON group (n=13) had a decrease in GH at 30-min (62%, p<0.05) and 60-min (61%, p<0.05) post exercise compared with baseline. The increase in GH from baseline to post was greater in the MOD group (p<0.05) and the decrease in CORT from pre to post was greater in the MOD group (p<0.05) than in the other groups. These data suggest that individual sessions of both low-intensity and moderate-intensity exercise can alter circulating anabolic and catabolic factors in HIV-infected men. The changes in the MOD group present potential mechanisms for the increases in lean tissue mass seen with resistance exercise training.

Grading the commercial optical biosensor literature-Class of 2008: 'The Mighty Binders'

Optical biosensor technology continues to be the method of choice for label-free, real-time interaction analysis. But when it comes to improving the quality of the biosensor literature, education should be fundamental. Of the 1413 articles published in 2008, less than 30% would pass the requirements for high-school chemistry. To teach by example, we spotlight 10 papers that illustrate how to implement the technology properly. Then we grade every paper published in 2008 on a scale from A to F and outline what features make a biosensor article fabulous, middling or abysmal. To help improve the quality of published data, we focus on a few experimental, analysis and presentation mistakes that are alarmingly common. With the literature as a guide, we want to ensure that no user is left behind.

Assessing the neuroendocrine stress response in the functional neuroimaging context

Neural regulation of stress responses, and the feedback of stress hormones to the brain, reflect complex brain-body interactions that may underlie the effects of psychological stress on health. Elucidating the brain circuitry involved in the cortical control of limbic-hypothalamic-pituitary-adrenal axis, and the cortical "targets" of cortisol that in turn modulates brain function, requires careful assessment of glucocorticoid hormones, in the context of the neuroimaging paradigms. Here we discuss approaches for assessment of endocrine function in the context of neuroimaging, including methods of blood and saliva specimen collection, and methods for drug/hormone administration. We also briefly discuss important temporal considerations, including appropriate timing of sample collections for hormones with different time-courses of activation (e.g. ACTH vs. cortisol), the pharmacokinetics of both endogenous hormones and administered agents, and circadian considerations. These are crucial to experimental designs of rhythmic hormonal systems and multiple feedback loops. We briefly address psychological/behavioral 'activation' paradigms used for inducing endogenous LHPA axis responses within or in proximity to scanner, as well as strategies for administration of exogenous hormones or secretagogues. Finally, we discuss some of the analytical issues in terms of hormone responses (e.g. response and area under curve, diurnal variability) and strategies for linking measured levels of peripheral humoral factor to brain activity (e.g. hormone responses as between-subject regressors of BOLD activations, hormone levels as within-subject regressors in analyses of covariance of brain activity over time, etc.).