Correlation between Salivary Mucin Concentration and Viscosity -An Exploratory Study in Healthy People / 대한연하장애학회지

Objective@#To analyze the rheological and biochemical properties of saliva in healthy adults. @*Methods@#The subjects were seven healthy young adults (20-39 years). The whole saliva was collected by the spitting method between 9:00 am and 12:00 am. Unstimulated saliva was collected first, which was followed by the collection of stimulated saliva using citric acid was collected. The viscosity was measured using a capillary viscometer to examine the rheological properties. The MUC5B concentration was analyzed using an enzyme-linked immunosorbent assay (ELISA) for the biochemical properties. @*Results@#Ten and five minutes were required on average for unstimulated saliva and stimulated saliva, respectively, to collect the minimum amount needed for analysis (8 ml). The flow rate increased from 1.037±0.323 ml/min to 1.823± 0.660 ml/min after stimulation (P=0.018). Citric acid stimulation also increased the MUC5B concentration in the saliva from 3.706±3.575 μg/ml to 6.928±2.03 μg/ml (P=0.028). The viscosity of saliva, however, did not show a significant difference between with (1.1±0.164 cSt) or without (1.019±0.08 cSt) stimulation (P=0.128). A positive correlation was observed between the flow rate and MUC5B concentration (Spearman’s rho=0.547, P=0.043). On the other hand, there was no significant correlation between the MUC5B concentration and viscosity both in the unstimulated and stimulated saliva (P=0.939 and 0.819, respectively). @*Conclusion@#No significant correlation was observed between the MUC5B concentration and viscosity. Considering the time required to collect samples, an analysis of the stimulated saliva appears feasible in various research settings.The feasibility of these analysis methods should be examined in a patient population.

Standard Recipes for the Preparation of Thickened Barium Liquids Used in the Diagnosis of Dysphagia

Barium sulfate is commonly used to prepare contrast media for videofluorograpy. The flow characteristics of thickened liquids formulated for oropharyngeal imaging are known to be greatly affected by the addition of barium. In this study, thickened barium liquids were prepared by mixing a commercial xanthan gum (XG)-based thickener (Visco-up®) at different concentrations (0.1%–3.0%) with barium powder (Baritop HD®), and differences in the viscosity between thickened non-barium and thickened barium liquids were investigated. In addition, the thickness levels of thickened barium liquids, which are based on the National Dysphagia Diet (NDD) and International Dysphagia Diet Standardization Initiative (IDDSI) guidelines, were classified by measuring the viscosity (NDD) and gravity flow through a syringe (IDDSI) with 0.1%–3.0% thickener concentrations. The apparent viscosity (η(a),₅₀) values of thickened barium liquids were much higher than those of thickened non-barium liquids, indicating that the addition of barium to the XG-based thickener resulted in further thickening. Standard recipes for preparing thickened barium liquids with desirable thickness levels were also established, showing the different thickener concentrations corresponding to the different NDD and IDDSI levels.

Effect of Salivary Reaction Time on Flow Properties of Commercial Food Thickeners Used for Dysphagic Patients

The effect of human saliva on the flow properties of pudding-like thickened water prepared with commercial food thickeners was investigated, and their viscosity differences were also compared as a function of salivary reaction time (0-60 min after the addition of saliva). Food thickeners used in this study were starch-based (SB), gum-containing starch-based (GSB), and gumbased (GB) commercial thickeners marketed in Korea. GB showed no significant reduction in viscosity upon contact with human saliva during the salivary reaction. In contrast, SB almost completely lost its viscosity shortly after the addition of saliva, and GSB significantly reduced its viscosity after 20 min of reaction time but retained its viscosity. The results of this study indicate that GB can enhance the swallowing safety of dysphagic patients by retaining a stable viscosity level without the reduction of viscosity during consumption of thickened fluids, whereas SB may increase the possibility of aspiration owing to a rapid decrease of viscosity upon contact with human saliva.