Salivary uric acid is a predictive marker of body fat percentage in adolescents

Alterations in salivary profile in individuals with dental caries and/or obesity: a systematic review and meta-analysis

OBJECTIVES

To investigate current evidence on the association of salivary profile with dental caries and obesity.

DATA/SOURCES

A comprehensive search was conducted on PubMed, Web of Science, Embase, ProQuest Medical Database, ProQuest Sci-Tech Premium, and Cochrane Library up to June 2024. Observational studies comparing salivary profiles in individuals with dental caries and/or obesity were included. The risk of bias was evaluated using the Newcastle-Ottawa Scale. Meta-analysis was utilised to estimate the overall weighted or standardised mean difference (WMD or SMD).

STUDY SELECTION

Fifty studies were included, comprising 47 cross-sectional studies and three longitudinal studies with only baseline data extracted. Meta-analysis demonstrated that individuals with caries had higher total antioxidant capacity (SMD: 1.78, P<0.001) and elevated levels of interleukin-6 (SMD: 3.41, P=0.004) and tumour necrosis factor-α (SMD: 0.61, P=0.005) in unstimulated whole saliva (UWS) compared to caries-free controls. Individuals with overweight/obesity, when compared to normal-weight counterparts, showed decreased UWS pH (WMD: -0.14, P=0.009), unstimulated and stimulated salivary flow rates (WMD: -0.09 mL/min, P=0.001 and WMD: -0.35 mL/min, P<0.001, respectively), phosphorus/phosphate levels in stimulated whole saliva (SWS) (SMD: -0.36, P=0.004), and peroxidase levels in both UWS (SMD: -1.56, P<0.001) and SWS (SMD: -1.10, P<0.001). Additionally, they exhibited higher levels of mutans streptococci (SMD: 0.47, P<0.001), secretory immunoglobulin A (WMD: 14.51 μg/mL, P=0.020), and total antioxidant capacity (SMD: 0.67, P<0.001) in UWS.

CONCLUSION

Although individuals with dental caries and/or obesity have altered salivary profiles, the quality of evidence remains low. Further high-quality studies are required to investigate the triadic associations in depth.

CLINICAL SIGNIFICANCE

Monitoring salivary parameters and biomarkers could serve as a relatively simple and non-invasive method for identifying, predicting, controlling, and monitoring individuals at high risk of dental caries and obesity. This knowledge can inform the development of tailored oral health promotion programs for individuals with obesity.

Distinguishable short-term effects of tea and water drinking on human saliva redox

Food consumption can alter the biochemistry and redox status of human saliva, and the serving temperature of food may also play a role. The study aimed to explore the immediate (3 min) and delayed (30 min) effects of hot tea (57 ± 0.5 °C) ingestion and cold tea (8 ± 0.5 °C) ingestion on the salivary flow rate and salivary redox-relevant attributes. The saliva was collected from 20 healthy adults before, 3-min after and 30-min after the tea ingestion. The hot or cold deionised water at the same temperatures were used as control. The salivary flow rate and redox markers in hot tea (HBT), cold tea (CBT), hot water (HW) and cold water (CW) group were analysed and compared. The results demonstrated that neither the black tea nor the water altered the salivary flow rate; the black tea immediately increased the salivary thiol (SH) and malondialdehyde (MDA) content while reduced salivary uric acid (UA) significantly. The tea ingestion showed a tendency to elevate the ferric reducing antioxidant power (FRAP) in saliva, although not significantly. The water ingestion decreased the MDA content immediately and increased the UA level significantly. Cold water was found to induce a greater delayed increase in total salivary total protein (TPC) than the hot water. In conclusion, the black tea ingestion affects the redox attributes of human saliva acutely and significantly, while the temperature of drink makes the secondary contribution.

Uric acid mediated the relationship between obesity and hypertension in children and adolescents: A population‑based cohort study

BACKGROUND AND AIM

Obesity and hyperuricemia (HUA) often coexist and have been widely accepted as risk factors for hypertension, but the role of uric acid (UA) in the relationship between obesity and hypertension remains unknown in children and adolescents.

METHODS AND RESULTS

A total of 7525 subjects aged 6-16 years were from the School-based Cardiovascular and Bone Health Promotion Program (SCVBH) at baseline (2017) and followed up in 2019. Multivariable logistic regression with interaction terms, cross-lagged panel analysis, and causal mediation model were applied to delineate the joint impact of obesity and HUA on hypertension, including the interaction effect, the temporal association, and the mediating effect of UA in the relationship between obesity and hypertension. There were 10.8 % of the participants with normotension at baseline developed hypertension after two years of follow-up. Cross-lagged panel analysis showed that the two-time point association was significant only from baseline BMI to follow-up UA (β1 = 0.302, P < 0.001), but not from baseline UA to follow-up BMI (β2 = 0.002, P = 0.745). Multivariable logistic regression showed that both obesity and HUA increased the risk of hypertension, but no interaction effect between HUA and obesity. The causal mediation analysis found that UA partially mediated the association between BMI and SBP (mediate proportion: 20.3 %, 95 % CI: 17.4-22.9 %) or DBP (mediate proportion: 11.9 %, 95 % CI: 3.9-18.2 %). The results were consistent in the analysis of systolic hypertension rather than diastolic hypertension.

CONCLUSIONS

It is mediating effect that UA played in the progress from obesity to hypertension, particularly systolic hypertension in children and adolescents.

Bypass gastroplasty impacts oral health, salivary inflammatory biomarkers, and microbiota: a controlled study

OBJECTIVES

Knowledge about the impact of gastroplasty on oral health and salivary biomarkers is limited. The aim was to prospectively evaluate oral health status, salivary inflammatory markers, and microbiota in patients undergoing gastroplasty compared with a control group undergoing a dietary program.

MATERIALS AND METHODS

Forty participants with obesity class II/III were included (20 individuals in each sex-matched group; 23-44 years). Dental status, salivary flow, buffering capacity, inflammatory cytokines, and uric acid were assessed. Salivary microbiological analysis (16S-rRNA sequencing) assessed the abundance of genus, species, and alpha diversity. Cluster analysis and mixed-model ANOVA were applied.

RESULTS

Oral health status, waist-to-hip ratio, and salivary alpha diversity were associated at baseline. A subtle improvement in food consumption markers was observed, although caries activity increased in both groups, and the gastroplasty group showed worse periodontal status after three months. IFNγ and IL10 levels decreased in the gastroplasty group at 3 months, while a decrease was observed in the control group at 6 months; IL6 decreased in both groups (p < 0.001). Salivary flow and buffering capacity did not change. Significant changes in Prevotella nigrescens and Porphyromonas endodontalis abundance were observed in both groups, while alpha diversity (Sobs, Chao1, Ace, Shannon, and Simpson) increased in the gastroplasty group.

CONCLUSIONS

Both interventions changed in different degrees the salivary inflammatory biomarkers and microbiota, but did not improve the periodontal status after 6 months.

CLINICAL RELEVANCE

Although the observed discrete improvement in dietary habits, caries activity increased with no clinical improvement in the periodontal status, emphasizing the need of oral health monitoring during obesity treatment.

Impact of gastroplasty on salivary characteristics, dental health status and oral sensory aspects: a controlled clinical study

BACKGROUND

Saliva is a non-invasive source of biomarkers useful in the study of different pathophysiological conditions. The qualitative and quantitative study of saliva, as well as the assessment of oral health, can be particularly useful for a better understanding of obesity due to its importance in the food oral perception and ingestion.

OBJECTIVES

To evaluate the effect of treatment of morbid obesity (dietary counselling versus gastroplasty) on salivary characteristics, oral sensory perception and dental health in a controlled study.

METHODS

73 adults (60 females; 19-59 years) with morbid obesity were divided in: Control group (CG; n=34) followed-up during a 6-months dietary program, and Gastroplasty group (GG; n=39) evaluated immediately before, 3, and 6 months after gastroplasty. Dietary habits, Oral Health Impact Profile and xerostomia complaints were investigated by interview. The clinical examination included anthropometric and caries experience evaluation. Salivary flow rate, buffering capacity, total protein and alpha-amylase levels, and sensitivity for the 4 basic tastes were assessed. Two-way mixed model and sign test were applied.

RESULTS

Physical and clinical aspects did not differ between groups in the beginning of the study, and GG showed a rapid weight loss after surgery (p<0.001). An improvement in most of the dietary aspects was observed, especially in the GG. A worsening in the dental health status was observed over time in both groups, with an increase in the number of filled and decayed teeth. CG showed a better oral health-related quality of life, while xerostomia complains increased in GG after gastroplasty. Salivary flow rate remained stable in both groups, but a decrease in buffering capacity, total protein, and alpha-amylase activity was observed in GG after 6-months; taste sensitivity increased from baseline to 6-months in GG (p<0.05).

CONCLUSION

After 6-months of follow-up, patients undergoing gastroplasty presented an improvement in dietary habits and taste sensitivity. However, changes in saliva composition and a worsening in dental health status and xerostomia complaints were also observed.

Viruses such as SARS-CoV-2 can be partially shielded from UV radiation when in particles generated by sneezing or coughing: Numerical simulations

UV radiation can inactivate viruses such as SARS-CoV-2. However, designing effective UV germicidal irradiation (UVGI) systems can be difficult because the effects of dried respiratory droplets and other fomites on UV light intensities are poorly understood. Numerical modeling of UV intensities inside virus-containing particles on surfaces can increase understanding of these possible reductions in UV intensity. We model UV intensities within spherical approximations of virions randomly positioned within spherical particles. The model virions and dried particles have sizes and optical properties to approximate SARS-CoV-2 and dried particles formed from respiratory droplets, respectively. In 1-, 5- and 9-µm diameter particles on a surface, illuminated by 260-nm UV light from a direction perpendicular to the surface, 0%, 10% and 18% (respectively) of simulated virions are exposed to intensities less than 1/100th of intensities in individually exposed virions (i.e., they are partially shielded). Even for 302-nm light (simulating sunlight), where absorption is small, 0% and 11% of virions in 1- and 9-µm particles have exposures 1/100th those of individually exposed virions. Shielding is small to negligible in sub-micron particles. Results show that shielding of virions in a particle can be reduced by illuminating a particle either from multiple widely separated incident directions, or by illuminating a particle rotating in air for a time sufficient to rotate through enough orientations. Because highly UV-reflective paints and surfaces can increase the angular ranges of illumination and the intensities within particles, they appear likely to be useful for reducing shielding of virions embedded within particles.

Serum Uric Acid Levels and Metabolic Indices in an Obese Population: A Cross-Sectional Study

OBJECTIVE

To analyze the association between serum uric acid (SUA) and metabolic state in obese inpatients and preliminarily explore potential mechanisms of hyperuricemia in obesity.

METHODS

A total of 153 obese inpatients were selected and assigned based on SUA level to the normal uric acid (NC group) or high uric acid (HUA) group. Patients' sex, age, height, weight, blood pressure, BMI, and prevalence of metabolic syndrome were collected and recorded. SUA, FPG, FIns, HOMA-IR, HOMA-IS, HbA_1c, TGs, TC, LDL-C, and HDL-C levels were tested. Pearson correlation analysis was performed to analyze the correlation between SUA and related metabolic indicators. Logistic regression was performed to analyze independent risk factors of hyperuricemia in obesity.

RESULTS

In the HUA group, the patients were predominantly males, and BMI, DBP, TGs, FPG, FIns, HOMA-IR, HOMA-IS, and metabolic syndrome were higher than those in the NC group (P<0.05), while HDL-C was lower than that in the NC group (P<0.05). There were no significant differences between the groups in TC or LDL-C. Pearson correlation analysis showed that in obese patients, SUA was positively correlated with BMI, FIns, HOMA-IR, HOMA-IS, TGs, andmetabolic syndrome and negatively correlated with age and HDL-C. Logistic regression showed that BMI, hyperinsulinemia, and insulin resistance were independent risk factors of hyperuricemia.

CONCLUSION

Development of hyperuricemia in obese populations might be correlated with hyperinsulinemia or insulin resistance.

Sample Preparation Methods for Lipidomics Approaches Used in Studies of Obesity

Obesity is associated with alterations in the composition and amounts of lipids. Lipids have over 1.7 million representatives. Most lipid groups differ in composition, properties and chemical structure. These small molecules control various metabolic pathways, determine the metabolism of other compounds and are substrates for the syntheses of different derivatives. Recently, lipidomics has become an important branch of medical/clinical sciences similar to proteomics and genomics. Due to the much higher lipid accumulation in obese patients and many alterations in the compositions of various groups of lipids, the methods used for sample preparations for lipidomic studies of samples from obese subjects sometimes have to be modified. Appropriate sample preparation methods allow for the identification of a wide range of analytes by advanced analytical methods, including mass spectrometry. This is especially the case in studies with obese subjects, as the amounts of some lipids are much higher, others are present in trace amounts, and obese subjects have some specific alterations of the lipid profile. As a result, it is best to use a method previously tested on samples from obese subjects. However, most of these methods can be also used in healthy, nonobese subjects or patients with other dyslipidemias. This review is an overview of sample preparation methods for analysis as one of the major critical steps in the overall analytical procedure.

Salivary Microbiological and Gingival Health Status Evaluation of Adolescents With Overweight and Obesity: A Cluster Analysis

Given the high prevalence of obesity in children and adolescents, the investigation of early markers is of clinical importance to better manage this condition. Thus, the aim was to evaluate the cross-sectional relationship between salivary microbiota, gingival health status, and excess weight in adolescents. A total of 248 students (14-17 y; 119 girls) were included, free of caries lesions and periodontal pockets. Physical examination included measures of height, weight, and body fat percentage (%BF). Oral examination was performed to gather information on dental (DMFT index) and gingival health status. Unstimulated saliva was submitted to qPCR reactions to quantify Streptococcus mutans, Porphyromonas gingivalis, Bifidobacteria, and Streptococcus pneumoniae percentages and the NFKappaB expression. Two-way ANOVA was applied considering group (normal-weight/overweight/obesity) and sex factors, in addition to cluster analysis. Group effect was significant for %S. mutans (partial eta² = 0.20; p < 0.001) and %Bifidobacteria (partial eta² = 0.19; p < 0.001), with overweight and obesity groups showing the highest levels compared to normal-weight ones, with no significant sex effect. There was no difference in the frequency of gingivitis, P. gingivalis, and S. pneumoniae percentages or NFKappaB expression between groups. Cluster analysis generated three clusters according to body fat accumulation: "Higher %BF," "Moderate %BF," and "Lower %BF." "Higher %BF" cluster was characterized by higher body fat percentage and higher salivary %Bifidobacteria, while cluster "Lower %BF" was characterized by lower body fat percentage and lower frequency of gingivitis ("Moderate %BF" cluster was the contrast). According to nutritional status, a difference in salivary S. mutans and Bifidobacteria percentages was found, with overweight or obesity adolescents showing the highest percentages than normal-weight ones. Besides, a positive relationship between body fat accumulation and Bifidobacteria count was observed, indicating a possible interaction between oral bacteria communities and weight gain.