WICOX: Weight-Based Integrated Cox Model for Time-to-Event Data in Distributed Databases Without Data-Sharing.

To exploit large-scale biomedical data, the application of common data models and the establishment of data networks are being actively carried out worldwide. However, due to the privacy issues, it is difficult to share data distributed among institutions. In this study, we developed and evaluated weight-based integrated Cox model (WICOX) as a privacy-protecting method without sharing patient-level information across institutions. WICOX generates a weight for each institutional model and builds an integrated model of multi-institutional data based on these weights. WICOX does not require iterative communication until the centralized parameter converges. We performed experiments to show the weight characteristic of our algorithm based on 10 hospitals (2910 intensive care unit (ICU) stays in total) from the electronic intensive care unit Collaborative Research Database to predict time to ICU mortality with eight risk factors. Compared with the centralized Cox model, WICOX showed biases from 0 to 0.68E-2, from 0.00E-2 to 4.98E-2, and from 0.74E-2 to 1.7E-2 for time-dependent AUC, log hazard ratio, and survival rate, respectively. In addition, through simulation results using real 10 hospitals, WICOX showed robust results in accuracy under any composition of hospitals. The results of the experiments highlight that WICOX has robust characteristics and provides predictive performance and statistical inference results nearly the same as those of the centralized model. WICOX is a non-iterative method using the weight of institutional model for implementing the Cox model across multiple institutions in a privacy-preserving manner.

Oral Probiotics, Streptococcus salivarius K12 and M18, Suppress the Release of Volatile Sulfur Compounds and a Virulent Protease from Oral Bacteria: An In-Vitro Study.

PURPOSE: To evaluate the inhibitory effects of Streptococcus salivarius K12 and M18 strains on the growth of six oral pathogens as well as their release of volatile sulfur compounds (VSCs), and whether these probiotics can inhibit the expression of arginine-specific gingipain A (RgpA), a protease secreted by Porphyromonas gingivalis. MATERIALS AND METHODS: After six halitogenic oral pathogens (P. gingivalis, Treponema denticola, Tannerella forsythia, Fusobacterium nucleatum, Parvimonas micra, and Eikenella corrodens) were cultured with or without S. salivarius K12 and M18, the concentration of two VSCs was measured. Moreover, the antimicrobial activity of S. salivarius K12 and M18 against these pathogens and the suppressive effect on RgpA release by P. gingivalis were assessed. RESULTS: In the co-culture of S. salivarius K12 or M18 with oral pathogenic bacteria, the growth of all six oral pathogens was significantly inhibited (p < 0.01). Additionally, S. salivarius K12 and M18 had an inhibitory effect on the production of the halitogenic substances H2S and CH3SH (p < 0.01) as well as the expression of P. gingivalis RgpA. Finally, we demonstrated that the addition of only culture supernatants of the two strains K12/M18 to oral pathogen cultures was sufficient to mimic the effects of K12/M18 co-cultures upon VSCs production and protease expression. CONCLUSIONS: S. salivarius K12 and M18 inhibited VSC release by all six of the major oral pathogens that were assayed and reduced the expression of RgpA.

Effects of Lingual and Palatal Site Toothbrushing on Periodontal Disease in the Elderly: A Cross-Sectional Study.

(1) Background: To analyze the association between periodontal health status and daily oral health activities including lingual and palatal site toothbrushing. (2) Methods: One hundred and fifty Korean elderly people aged >65 years participated in the study. Clinical examination regarding oral health status, including periodontal health status, was evaluated, and data on the oral health activities, socio-demographic factors, and systemic health-related factors were obtained using a questionnaire. Statistical analyses assessed the differences of periodontal health status according to daily oral health activities, including lingual and palatal site toothbrushing. (3) Results: Oral health activities including lingual and palatal site toothbrushing, frequency of toothbrushing, use of an interdental toothbrush, dietary patterns, and activity dependence correlated with bleeding on probing (BOP) and periodontitis. After adjusting for covariates, the prevalence of periodontitis was lower in the group where the inner surfaces of the teeth were partially or wholly cleaned than in the group without such cleaning. High BOP was significantly associated with the brushing of the inner surfaces of teeth. (4) Conclusions: Lingual and palatal site toothbrushing was associated with good periodontal health status in the elderly; the importance of brushing the inner surfaces of teeth should be emphasized for them and their caregivers.

Association of Some Vitamins and Minerals with Periodontitis in a Nationally Representative Sample of Korean Young Adults.

The purpose of this study was to investigate whether the intakes of some kinds of vitamins and minerals are associated with periodontitis in a nationally representative sample of young adults. This study comprised 2049 young adults aged 19-39 years who took both periodontal examination and nutrition survey. The vitamin and mineral intakes were calculated from dietary intake data gained by complete one-day 24-h recall interviews, and the intake levels for each nutrient were classified by the Recommended Nutrient Intake (RNI) in Dietary Reference Intakes for Koreans and median values. Periodontitis was assessed using Community Periodontal Index (CPI). Multivariate logistic regression analyses were performed in a whole sample and subgroups with the strata of gender or smoking, following a complex sampling design. In analyses according to RNI, a lower intake of niacin was significantly associated with periodontitis in young adults (odd ratio [OR] 1.47, 95% confidential interval [CI] 1.09-2.00) and in its subgroup of women (OR 1.70; 95% CI 1.10-2.64) and current non-smokers (OR 1.75; 95% CI 1.22-2.51). Whereas, in analyses according to median intake values, there were significant associations of periodontitis with a lower intake of niacin in women (OR 1.58; 95% CI 1.02-2.46) and current non-smokers (OR 1.50; 95% CI 1.01-2.22), with lower intake of vitamin C in women (OR 1.66; 95% CI 1.04-2.64) and in current non-smokers (OR 1.49; 95% CI 1.04-2.14), with lower intake of iron in women (OR 1.85; 95% CI 1.11-3.07), and with lower intake of vitamin A marginally in women (OR 1.56; 95% CI 1.00-2.44). In young adults, periodonitis is significantly associated with the lower intakes of niacin, vitamin C, and iron, especially in women and current non-smokers.

Association between plasma levels of manganese and periodontal status: a study based on the fourth Korean National Health and Nutrition Examination Survey.

BACKGROUND: This study aims to evaluate the association between plasma levels of manganese (Mn) and periodontal status in a representative sample of Korean adults. METHODS: Plasma levels of Mn and periodontal status were analyzed in 1,679 participants, all of whom were ≥19 years old. Plasma levels of Mn were divided into four quartiles: first (<1.057 µg/dL), second (1.057 to 1.274 µg/dL), third (1.275 to 1.544 µg/dL), and fourth (>1.544 µg/dL). Periodontal status was assessed using the Community Periodontal Index (CPI). Multivariate logistic regression analyses were performed after adjusting for sociodemographic variables, oral and general health behavior, oral health status, and systemic conditions. All analyses took into consideration the complex sampling design, and multivariate analyses were performed in the subgroups. RESULTS: Multivariate logistic regression analyses revealed a significant association between plasma levels of Mn and higher CPI in the total sample. There was a moderate association between first-quartile plasma levels of Mn and higher CPI in males (odds ratio [OR]: 2.13; 95% confidence interval [CI] 1.25 to 3.63) and current smokers (OR: 2.07; 95% CI 1.04 to 4.11), compared to the fourth quartile. CONCLUSION: Periodontal status is significantly associated with plasma levels of Mn in Korean adults, especially in men and smokers.