The combined effects of polystyrene of different sizes and cadmium in mouse kidney tissues.

Environmental accumulation of nano- and microplastics pose serious risks to human health. Polystyrene (PS) is a polymer commonly used in the production of plastics. However, PS can adsorb cadmium (Cd), thereby influencing bioavailability and toxicity in vivo. Moreover, PS and Cd can accumulate in the mammalian kidney. Therefore, the aim of the present study was to assess the effects of combined exposure to PS and Cd in the kidney. Kidney damage was evaluated in male mice gavaged with PS (diameter, 100 nm and/or 1 µm) and Cd for 25 days.The results showed that PS at 100 nm caused more severe oxidative damage and cell apoptosis than PS at 1 µm. Combined exposure to PS at both 100 nm and 1 µm caused more severe kidney damage than the single administration groups. The extent of kidney toxicity caused by Cd differed with the combination of PS particles at 100 nm vs. 1 µm. The degree of damage to kidney function, pathological changes, and cell apoptosis induced by Cd+100 nm PS+1µm PS was the most severe. An increase in the Bax/Bcl2 ratio and overexpression of p53 and caspase-3 revealed that renal cell apoptosis might be induced via the mitochondrial pathway. Collectively, these findings demonstrate that the size of PS particles dictates the combined effects of PS and Cd in kidney tissues. Kidney damage caused by the combination of different sizes of PS particle and Cd is more complicated under actual environmental conditions.

Detection of microplastics in domestic and fetal pigs' lung tissue in natural environment: A preliminary study.

Microplastics (MPs) are ubiquitous in the environment. However, it is unclear whether MPs are present in mammalian lungs through inhalation, and if so, could be possibly found in fetal tissues. In this study, we aim to determine the presence and characteristics of particles in domestic and fetal pig lung tissue in the natural environment. Specimens from the lungs of domestic pigs (n = 10) and fetal pigs that already died in matrix during vaginal birth from the non-contaminated area (n = 10) were obtained from farmers' nearby sludge treatment plant. These specimens were compressed between two glass microscope slides, which were examined under polarized light microscopy. In addition, Agilent 8700 LDIR Chemical imaging system (LDIR) was used to determine the quantitative and qualitative characteristics of MPs. According to the polarized light microscope survey of domestic pig lungs, we observed an average of 12 particles/g, which was more than the 6 particles/g observed in fetal pig lungs, which ranged in size from 115.14 µm to 1370.43 µm. All the observed MP particles were fiber in shape. LDIR indicated an average of 180 particles/g of domestic pig lungs, ranging in size from 20.34 µm to 916.36 µm, which was twice as many MPs observed in fetal pig lungs. Furthermore, the compositions of MPs were different between them. LDIR indicated that polyamide (PA) was the most common polymer identified in domestic pig lungs (46.11%), while polycarbonate (PC) was the most common polymer in fetal pig lungs (32.99%). These findings confirmed the presence of MPs in the lung tissue of both domestic and fetal pigs in the natural environment, but the main characteristics differed. This fact indicated the increasing risk of MPs to human respiratory tract is increasing. Further research should be conducted to entirely estimate the specific exposure level on humans and offspring.

A composite oral hygiene score and the risk of oral cancer and its subtypes: a large-scale propensity score-based study.

OBJECTIVE: This study aimed to investigate the potential relationship between oral hygiene and the risk of oral cancer and its subtypes after controlling the effects of several confounding factors. MATERIALS AND METHODS: A large-scale case-control study was conducted from January 2010 to August 2019, recruiting a total of 1,288 oral cancer cases with newly diagnosed and 4,234 healthy controls. Propensity score matching (PSM) and inverse probability of treatment weighting (IPTW) were utilized to minimize confounding effects. Conditional logistic regression was used to evaluate the effects of oral hygiene indicators on oral cancer. RESULTS: A composite oral hygiene score was developed based on five indicators selected based on PSM and IPTW analysis (including tooth loss, dentures wearing, the frequency of tooth brushing, regular dental visits, and recurrent dental ulcer). Participants with a higher score, compared with their lower counterparts, showed a 49% increased risk (the odds ratio (OR) was 1.49 (95% confidence interval (CI): 1.26-1.75). A similar association pattern was found following IPTW analyses (OR = 1.32; 95% CI: 1.22-1.42). Of note, the adverse effects of poor oral hygiene were more evident among the sites of gingival and buccal (PSM analysis: 2.03-fold and 2.68-fold increased risk; IPTW analysis: 1.57-fold and 2.07-fold increased risk, respectively). Additionally, a greater positive association was observed between poor oral hygiene and oral squamous cell carcinoma, compared with other pathological types. CONCLUSION: This study establishes a composite oral hygiene score and provides supportive evidence of poor oral hygiene associated with a higher risk of oral cancer, particularly in the gingival and buccal mucosa sites and in the squamous cell carcinoma. CLINICAL RELEVANCE: The data highlights the importance of improving poor oral hygiene habits, which has public health implications for the prevention of oral cancer.

The effect of formal statistical courses attitudes on learning outcomes in a cohort of undergraduate dental students.

INTRODUCTION: Whilst statistical knowledge is essential for dental students' academic or professional careers, only a few studies have measured the attitudes of these students towards statistics courses. This study aimed to investigate the attitudes of a cohort of dental students towards a formal statistical course and explore the factors that are potentially related to these attitudes. METHODS: A survey was performed amongst dental students of 2017 entry at Fujian Medical University, China. The questionnaire covers three aspects: demographic characteristics, educational background and attitudes towards formal statistics courses. RESULTS: A total of 103 dental students enrolled for the survey, and the response rate was 100.0%. 44.7% of dental students had positive attitudes towards formal statistics courses with an overall average of 25.7 (SD = 2.2, out of 30). Students' computer skills, expectations of course achievement, attention in class and learning atmosphere of the class were significantly associated with the attitudes towards formal statistics courses. Moreover, students with positive attitudes experienced a greater improvement in the statistical cognition and application ability of statistical methods after the course than those with negative/neutral attitudes. Additionally, a positive correlation was observed between students' attitudes and achievement in the examination. CONCLUSION: These results suggest that attitudes are critical to the learning effectiveness in formal statistics courses amongst undergraduate dental students. All the educators involved should monitor the students' attitudes in the teaching process and make effective interventions to improve students' attitudes towards formal statistics courses.

[Association between oral hygiene, chronic diseases, and oral squamous cell carcinoma].

OBJECTIVE: To investigate the association between oral hygiene, chronic diseases, and oral squamous cell carcinoma. METHODS: We performed a case-control study with 414 cases and 870 controls in Fujian during September 2010 to January 2015. Patients were newly diagnosed oral squamous cell carcinoma cases according to the pathologic diagnoses, control subjects were enrolled from community population. Epidemiological data were collected by in-person interviews using a standard questionnaire. The contents of the questionnaire included demography character, history of tobacco smoking and alcohol drinking, dietary habits, oral hygiene status, family history of cancer, etc. Using unconditional logistic regression analysis to estimate adjusted odds ratios (OR) and corresponding 95% confidence intervals (CI) for oral hygiene and chronic diseases. We also stratified by sex, smoking and drinking to explore possible difference in association between subgroups. RESULTS: The multivariate logistic regression analysis indicated that number of teeth (20-27 and < 20), bad prosthesis, recurrent oral ulceration were the risk factors of oral squamous cell carcinoma, the adjusted OR (95% CI) values were 2.01 (1.49-2.73), 3.51 (2.39-5.15), 2.33 (1.79-3.04), 3.96 (2.11-7.44), respectively; brushing tooth once per bay, brushing tooth more than once per day, regular oral health examination at least 5 years per time were the protective factors of oral squamous cell carcinoma, the adjusted OR (95% CI) values were 0.24 (0.13-0.43), 0.13 (0.07-0.24), 0.37 (0.26-0.53), respectively. The stratification analysis indicated that recurrent oral ulceration could increase the risk of oral squamous cell carcinoma for non-smokers and non-drinking, the adjusted OR (95% CI) value was 5.21 (2.42-11.18) and 4.71 (2.37-9.36); and a risky effect of hypertension on risk of oral squamous cell carcinoma was observed for non-smokers and non-drinking, the adjusted OR (95% CI) values were 1.70 (1.10-2.61) and 1.58 (1.07-2.34). CONCLUSIONS: Oral hygiene and chronic diseases could affect the incidence of oral squamous cell carcinoma.

[Influencing factors for oral-maxillofacial benign tumors: a case-control study].

OBJECTIVE: To investigate the clinical influence factors of oral-maxillofacial benign tumors. METHODS: We conducted a case-control study with 113 cases newly diagnosed primary oral-maxillofacial benign tumors and 584 cases controls from a hospital in Fujian from September 2010 to January 2015. Epidemiological data were collected by in-person interviews using a standard questionnaire. The contents of the questionnaire included demography character, history of tobacco smoking and alcohol drinking, dietary habits, oral hygiene status, family history of cancer, etc. Unconditional logistic regression was used to research the relationship between the factors and oral-maxillofacial benign tumors. RESULTS: Multivariable analysis showed that risk factors of oral-maxillofacial benign tumors included: cigarette smoking index above 1 000, passive smoking before the age of 18, age of wearing bad prosthesis between 33 to 55 years old and high blood pressure; the corresponding OR (95% CI) values were 14.63 (3.88-55.13), 2.34 (1.19-4.62), 2.35 (1.17-4.73), 3.46 (1.71-7.00), respectively; Protective factors included: regularly intake of meat above 1 time/day, fruits, health care products and vitamin tablets, brushing teeth above 1 time per day and oral examination above 5 years/time, the corresponding OR (95% CI) values were 0.22 (0.07-0.70), 0.18 (0.08-0.41), 0.32 (0.11-0.88), 0.22 (0.07-0.73), 0.28 (0.16-0.48), 0.28 (0.13-0.60), respectively. CONCLUSION: Abstinence from tobacco smoking, reduce passive smoking before the age of 18, regularly intake of meat, fruits, health care products and vitamin tablets, and oral examination at regular time might have impact on the incidence of oral-maxillofacial benign tumors to a certain extent.

Blood uptake and urine excretion of nano- and micro-plastics after a single exposure.

Nano- and micro-plastic (NMP) pollution has emerged as a global issue; however, uptake in the blood is controversial. Also, there is no evidence that NMPs are excreted via urine. This study was designed to clarify the time course of NMPs absorption in blood and the excretion in urine. Male mice received a single administration of fluorescent polystyrene (PS) beads (100-nm and 3-µm) via tail vein injection, gavage, or pulmonary perfusion. Blood and urine samples were measured 0.5, 1, 2, and 4 h after exposure by confocal laser scanning microscope (CLSM). Transmission electron microscopy (TEM) was performed to corroborate the findings. Fluorescence particles were detected in both blood and urine from the 100-nm and 3-µm PS-treated groups after exposure. In the 3-µm PS treated group, particles with corresponding diameters were detected after intravenous injection and pulmonary perfusion, and particles with a diameter <3 µm were detected in blood samples after gavage. The fluorescent signal in urine was particularly weak and the size was <3 µm. Significant time course changes in fluorescence intensity were demonstrated in blood and urine (P < 0.05) after intravenous injection and pulmonary perfusion in the 100-nm PS-treated group. By contrast, significant changes were detected in the urine (P < 0.05), but not the blood, after gavage. TEM confirmed the presence of particles with corresponding diameters in blood samples; however, the excretion in urine was difficult to confirm for nano-plastics (NPs) and micro-plastics (MPs) because all particles with diameters of approximately 100 nm and 3 µm had irregular shapes and no clear boundaries. Our findings revealed that both NPs and MPs enter the blood circulation through digestive and respiratory pathways. Both 100-nm and 3-µm NMPs may be excreted through urine, but further evidence is needed. The physical and chemical properties of MPs may be impacted by digestive processes in vivo.

Exposure to microplastics in the upper respiratory tract of indoor and outdoor workers.

The aim of this study was to determine the presence of microplastics (MPs) in the upper respiratory tract of indoor and outdoor workers, to assess the type and the extent of contamination. Sputum and nasal lavage fluid were collected, and plastic particles were quantitatively analyzed by polarizing microscopy and a laser direct infrared chemical imaging system. The polarized light microscopy results showed that suspicious MPs were found in the nasal lavage and sputum of both couriers and office staff, and the abundance of MPs in the nasal lavage of office staff was significantly higher than in couriers (P < 0.0001). The chemical imaging results showed that polycarbonate (24.2%) and polyvinylchloride (PVC) (23.0%) were the predominant plastic materials in the sputum of couriers, while polyamide (PA) (25.3%) and polyethylene (22.9%) were dominant in the nasal lavage fluid. The sputum and nasal lavage fluid of office staff were both dominated by PVC (39.1% and 41.1%, respectively) and PA (24.8% and 31.6%, respectively). Therefore, this study revealed that microplastic pollution was found in the respiratory tract of both indoor and outdoor workers, but the distribution of MP particles differed between the two populations.

Nomograms and risk scores for predicting the risk of oral cancer in different sexes: a large-scale case-control study.

Background: Although previous studies have explored the associations of modifiable lifestyle factors with oral cancer risk, few studies integrated these factors and established predictive tools for oral cancer risk in different sexes. Methods: Using a case-control study design, a total of 978 oral cancer cases and 2646 healthy controls were recruited in this study. Nomograms were constructed according to significant factors in multivariable logistic regression. Risk scores were calculated based on the nomograms and quantified the risk of oral cancer using restricted cubic spline. Results: Multivariate analyses demonstrated that smoking, alcohol drinking, tea, intake of fish, seafood, vegetables, fruits, teeth loss, regular dental visits and repetitive dental ulcer were independent factors for male oral cancer. Passive smoking, age at first intercourse, cooking oil fumes exposure, tea, intake of beans, vegetables, fruits, teeth loss, regular dental visits and repetitive dental ulcer were associated with female oral cancer. Then, two nomograms were developed for predicting the probability of oral cancer in men and women with the C-index of 0.768 (95% CI: 0.723-0.813) and 0.700 (95% CI: 0.635-0.765), respectively. Restricted cubic splines graphically revealed the risk of oral cancer in individuals with different risk scores. Moreover, the risk escalated continuously with the increasing number of the risk scores among both sexes. Conclusions: Combining nomograms with risk scores developed in this study could precisely predict oral cancer occurrence and provide an accurate risk assessment.

A novel prognostic index for oral squamous cell carcinoma patients with surgically treated.

This study aims to develop an applicable prognostic index with conventional factors for predicting outcome of patients with oral squamous cell carcinoma (OSCC). We performed a prospective study in a large cohort of 892 OSCC patients in Fujian, China. All patients were randomly divided into a discovery group and validation group. A prognostic index was developed based on ß value of each significant variable obtained from the multivariate Cox regression model. The results from discovery and validation set demonstrated thatthe model-4(included clinical stage, tumor differentiation, ill-fitting denture, oral hygiene and cigarette smoking) was the optimal model. The optimal cutoff points of prognostic index (1.88 and 2.80) were determined by X-tile program which categorized all subjects into low, middle and high risk subsets. Patients in high risk group were at the greatest risk of death compared with those in low risk group (HR: 6.02; 95%CI: 4.33-8.38). Moreover, there was a significant tendency of the worse overall survival with the higher prognostic index (Ptrend <0.001). The discriminatory capacity of prognostic index was 0.661(95%CI: 0.621-0.701). This study developed and validated a prognostic index that is an economical and useful tool for predicting the clinical outcomes of OSCC patients in Southeast China. Future randomized trials with larger cohort are required to confirm our results.

Differences in modifiable factors of oral squamous cell carcinoma in the upper and lower of oral fissure.

The aim of this study was to explore differences in the effects of modifiable factors on oral squamous cell carcinoma (OSCC) occurring in the lower oral fissure (LOF) and upper oral fissure (UOF). We conducted a case-control study with 697 OSCC patients (119 UOF and 578 LOF) and 1910 frequency-matched controls in Fujian province, China. Data on demographic characteristics and possible modifiable factors was collected using a structured questionnaire. Unconditional logistic regression was utilized to calculate the odds ratios (ORs) and corresponding 95% confidence intervals (CIs). Alcohol drinking was more strongly associated with an increased risk of OSCC-LOF than OSCC-UOF. Tobacco smoking, the number of teeth lost ≥5, wearing denture, and recurrent oral ulceration showed similarly associations with OSCC-LOF and -UOF risk. Similarly, the beneficial effects of tea consumption, tooth-brushing ≥2times per day, high intake of fresh fish, seafood, green-leafy vegetables, other vegetables and fruits were not significantly different on OSCC-LOF and -UOF. Although most of the modifiable factors exert similar effects on both OSCC sites, this study suggests that the sites of oral cavity in LOF may be affected more by alcohol drinking than the sites in UOF. Further studies with larger samples are warranted to confirm our findings.