Nitration of the salivary component 4-hydroxyphenylacetic acid in the human oral cavity: enhancement of nitration under acidic conditions

Estimation of Salivary 8-Hydroxydeoxyguanosine (8-OHdG) as a Potential Biomarker in Assessing Progression towards Malignancy: A Case-Control Study

Objective:

Squamous Cell Carcinoma is almost always preceded by potentially malignant disorders in the oral cavity before malignant transformation. Characterization of 8-OHdG from the saliva offers a relatively non-invasive, simple and efficient methodology for monitoring oxidative stress in subjects of Premalignant oral disorders (PMOD) and Oral Squamous Cell Carcinoma (OSCC). Hence the aim of the current study is to estimate the levels of salivary 8-hydroxydeoxyguanosine (8-OHdG) as a potential DNA Damage Biomarker in OSMF and OSCC patients in comparison to healthy individuals to assess disease progression from potentially malignant oral disorder to frank malignancy.

Materials and Methods:

The study was conducted among 90 patients [Oral Squamous cell carcinoma (n=30) and Oral Submucous Fibrosis (n=30) and healthy gender and age matched controls (n=30)]. 4ml of unstimulated saliva was collected from each of the subjects and was subjected to Sandwich ELISA for the quantification of salivary 8-OHdG. Statistical analysis was done using ANOVA, and p value was set at ≤0.05.

Results:

The mean age of OSCC patients were 56.8±11.8 years. Smoking was the most prevalent adverse habit among this group (66.6%) followed by Smokeless tobacco chewers (40%). The mean age of OSMF patients was 46.2± 9.8 years. Smokeless tobacco was the most predominant habit among the OSMF patients (83.33%) followed by smoking (33.33%). The mean OHdG levels among the controls was 6.59±1.47 (ng/dl) and almost doubled in patients of OSMF 13.89±1.96(ng/dL) and further raised in OSCC patients 19.96 ± 2.11 (ng/dL). These levels showed a highly significant difference (p <0.0001) in mean on comparison by using one-way ANOVA. Pearson correlation between the groups were also statistically significant (p=0.000).

Conclusion:

There were significant differences in the concentration of salivary 8-OHdG between healthy controls, OSMF, and OSCC patients. Hence, 8-OHdG can be used as a novel biomarker of DNA damage to assess disease progression.

Microbial and metabolomic analysis of gingival crevicular fluid in general chronic periodontitis patients: lessons for a predictive, preventive, and personalized medical approach

Objectives

General chronic periodontitis (GCP) is a bacterial inflammatory disease with complex pathology. Despite extensive studies published on the variation in the oral microbiota and metabolic profiles of GCP patients, information is lacking regarding the correlation between host-bacterial interactions and biochemical metabolism. This study aimed to analyze the oral microbiome, the oral metabolome, and the link between them and to identify potential molecules as useful biomarkers for predictive, preventive, and personalized medicine (PPPM) in GCP.

Methods

In this study, gingival crevicular fluid (GCF) samples were collected from patients with GCP (n = 30) and healthy controls (n = 28). The abundance of oral microbiota constituents was obtained by Illumina sequencing, and the relative level of metabolites was measured by gas chromatography-mass spectrometry. Full-mouth probing depth, clinical attachment loss, and bleeding on probing were recorded as indices of periodontal disease.

Results

The relative abundances of 7 phyla and 82 genera differed significantly between the GCP and healthy groups. Seventeen differential metabolites involved in different metabolism pathways were selected based on variable influence on projection values (VIP > 1) and P values (P < 0.05). Through Spearman's correlation analysis, microorganisms, metabolites in GCF, and clinical data together showed a clear trend, and clinical data regarding periodontitis can be reflected in the shift of the oral microbial community and the change in metabolites in GCF. A combination of citramalic acid and N-carbamylglutamate yielded satisfactory accuracy (AUC = 0.876) for the predictive diagnosis of GCP.

Conclusions

Dysbiosis in the polymicrobial community structure and changes in metabolism could be mechanisms underlying periodontitis. The differential microorganisms and metabolites in GCF between periodontitis patients and healthy individuals are possibly biomarkers, pointing to a potential strategy for the prediction, diagnosis, prognosis, and management of personalized periodontal therapy.

Metabolomic analysis of the saliva of Japanese patients with oral squamous cell carcinoma

The aim of the present study was to characterize the metabolic systems in Japanese patients with oral squamous cell carcinoma (OSCC) using capillary electrophoresis-mass spectrometry (CE-MS) metabolome analysis of saliva samples. A previous study showed variations among ethnicities and tumor sites in the saliva metabolome of patients with OSCC using CE-MS. In the present study, saliva was obtained from 22 Japanese patients with OSCC and from 21 healthy controls who visited the Department of Dentistry, Oral and Maxillofacial Surgery, Tokyo Dental Collage Ichikawa General Hospital, Tokyo, Japan, and all samples were subject to comprehensive quantitative metabolome analysis using CE-MS. A total of 499 metabolites were detected as CE-MS peaks in the saliva tested from the two groups. A total of 25 metabolites were revealed as potential markers to discriminate between patients with OSCC and healthy controls: Choline, p-hydroxyphenylacetic acid, and 2-hydroxy-4-methylvaleric acid (P<0.001); valine, 3-phenyllactic acid, leucine, hexanoic acid, octanoic acid, terephthalic acid, γ-butyrobetaine, and 3-(4-hydroxyphenyl)propionic acid (P<0.01); and isoleucine, tryptophan, 3-phenylpropionic acid, 2-hydroxyvaleric acid, butyric acid, cadaverine, 2-oxoisovaleric acid, N6,N6,N6-trimethyllysine, taurine, glycolic acid, 3-hydroxybutyric acid, heptanoic acid, alanine, and urea (P<0.05, according to the Wilcoxon rank sum test). A previous study by Sugimoto and co-workers detected 24 discriminatory metabolites, 7 of which (taurine, valine, leucine, isoleucine, choline, cadaverine, and tryptophan) were also detected in the present study. In the present study, however, choline, metabolites in the branched chain amino acids (BCAA) cycle, urea, and 3-hydroxybutyric acid were also characterized. Choline and metabolites of the BCAA cycle have previously been reported in OSCC using metabolome analysis. To the best of our knowledge, no previous reports have identified urea and 3-hydroxybuyric acid in the metabolome of patients with OSCC. These findings suggest the usefulness of metabolites as salivary biomarkers for Japanese patients with OSCC. Further studies using larger patient cohorts should be conducted to validate these results.

A population-based study on the association between the intake of soft drinks and periodontal disease in Taiwanese adults aged 35-44 years (KCIS no. 33)

OBJECTIVE

To elucidate the association between the intake of soft drinks and periodontal disease (PD) among Taiwanese middle-aged adults.

DESIGN

The cross-sectional design was employed to assess a dose-response relationship between the intake of soft drinks and PD after controlling for relevant confounding factors, with adjusted odds ratios obtained from a multivariate logistic regression model.

SETTING

Keelung Community-based Integrated Screening (KCIS) programme, Keelung, Taiwan.

SUBJECTS

Participants (n 10 213) aged 35-44 years who had undergone oral checks for PD between 2005 and 2009.

RESULTS

A dose-response relationship between the intake of soft drinks and elevated risk for PD defined by community periodontal index ≥3 (the current status of PD) was noted (P=0·02 by trend test). Compared with infrequent intake of soft drinks (≤2 times/week), the adjusted OR increased from 1·05 (95 % CI 0·92, 1·20) for the frequency of 3-4 times/week to 1·17 (95 % CI 1·03, 1·34) for the frequency of ≥5 times/week. A similar trend (P<0·01) was also observed for PD defined by loss of attachment ≥1 (representing the long-term cumulative gum damage due to PD).

CONCLUSIONS

A dose-response relationship between the intake frequency of soft drinks and PD was observed in Taiwanese middle-aged adults. Such evidence could be used in health promotion to support reductions in soft drink intake.

Hesperidin as a preventive resistance agent in MCF-7 breast cancer cells line resistance to doxorubicin

OBJECTIVE

To evaluate of hesperidin to overcome resistance of doxorubicin in MCF-7 resistant doxorubicin cells (MCF-7/Dox) in cytotoxicity apoptosis and P-glycoprotein (Pgp) expression in combination with doxorubicin.

METHODS

The cytotoxic properties, 50% inhibition concentration (IC50) and its combination with doxorubicin in MCF-7 cell lines resistant to doxorubicin (MCF-7/Dox) cells were determined using MTT assay. Apoptosis induction was examined by double staining assay using ethidium bromide-acridine orange. Immunocytochemistry assay was performed to determine the level and localization of Pgp.

RESULTS

Single treatment of hesperidin showed cytotoxic activity on MCF-7/Dox cells with IC50 value of 11 µmol/L. Thus, combination treatment from hesperidin and doxorubicin showed addictive and antagonist effect (CI>1.0). Hesperidin did not increase the apoptotic induction, but decreased the Pgp expressions level when combined with doxorubicin in low concentration.

CONCLUSIONS

Hesperidin has cytotoxic effect on MCF-7/Dox cells with IC50 of 11 µmol/L. Hesperidin did not increased the apoptotic induction combined with doxorubicin. Co-chemotherapy application of doxorubicin and hesperidin on MCF-7/Dox cells showed synergism effect through inhibition of Pgp expression.

Metabolism of [2-14C]p-hydroxyphenyl acetic acid in rat, monkey and human hepatocytes and in bile-duct cannulated rats

We determined the metabolism of [2-(14)C]p-hydroxyphenyl acetic acid (p-HPA) in rat (male, Sprague-Dawley), monkey (male, Cynomolgus), and human (male, Caucasian) hepatocytes, and in bile-duct cannulated (BDC) rats (male, Sprague-Dawley). Unchanged p-HPA ranged from 87.0 to 92.6% of the total radioactivity (TRA) in the extracts of rat, monkey, and human hepatocytes. Metabolites M1 (a glucuronide conjugate of p-HPA) and M2 (a glycine conjugate of p-HPA) were detected, accounting for 1-4% of TRA. After an oral dose of [2-(14)C]p-HPA to BDC rats, p-HPA-related components was predominantly excreted in urine, accounting for 83% of the dose. Bile excretion was limited, accounting for only 1.5% of the dose. Unchanged p-HPA was the predominant radioactivity in plasma (84.6% of the TRA in 1-h pooled plasma) and urine (69.6% of the dose). Metabolites M1, M2, and M3 (a glucuronide of p-HPA) were all detected in plasma, urine, and bile as minor components. In summary, p-HPA was not metabolized extensively in rat, monkey, and human hepatocytes. In rats, absorption and elimination of p-HPA were nearly complete with urinary excretion of the unchanged p-HPA as the predominant route of elimination after oral dosing. No oxidative metabolites were detected, suggesting a minimal role for P450 enzymes in its overall metabolic clearance. Therefore, p-HPA has a low potential for drug-drug interactions mediated by the concomitant inhibitors and inducers of P450 enzymes.

Nitrogen dioxide-dependent oxidation of uric acid in the human oral cavity under acidic conditions: implications for its occurrence in acidic dental plaque

The pH in dental plaque falls to below 5 after the ingestion of foods, and it may remain low if acid-tolerant bacteria grow in the plaque. Certain nitrate-reducing bacteria in the oral cavity can proliferate in dental plaque at low pH, and nitrite is detected in such plaque. In acidic dental plaque, NO(2) can be produced by self-decomposition of nitrous acid and also by peroxidase-catalyzed oxidation of nitrite, and it may oxidize uric acid, a major antioxidant in the oral cavity. Under experimental conditions that simulate oral cavity, the oxidation of uric acid by nitrite and by nitrite/peroxidase systems was much more rapid at pH 5 than at pH 7, suggesting the more rapid production of NO(2) in dental plaque at lower pH. We propose that if the pH of plaque developed in a dental crevice decreased, NO(2) and other nitrogen oxides produced in the plaque would diffuse into the adjoining gingival tissues. The results of this study seem to contribute to the understanding of the induction of periodontal diseases in the context of nitrite-dependent production of nitrogen oxides in acidic dental plaque.