Impact of occupational noise exposure on the hearing level in hospital staffs: a longitudinal study.

The study aimed to evaluate the impact of occupational noise on hearing loss among healthcare workers using audiometry. A longitudinal study was conducted with a six-month follow-up period in a hospital with 21 participants, divided into high-noise-exposure (HNE) and low-noise-exposure (LNE) groups. Mean noise levels were higher in the HNE group (70.4 ± 4.5 dBA), and hearing loss was measured using pure-tone audiometry at baseline and follow-up. The HNE group had significantly higher mean threshold levels at frequencies of 0.25 kHz, 0.5 kHz, 4.0 kHz, and an average of 0.5, 1, 2, and 4 kHz (all p-values < 0.05) after the follow-up period. After adjusting for confounding factors, the HNE group had significantly higher hearing loss levels at 0.25 kHz, 0.5 kHz, and average frequencies of 0.5, 1, 2, and 4 kHz compared to the LNE group at the second measurement. Occupational noise levels above 65 dBA over six months were found to cause significant threshold changes at frequencies of 0.25 kHz, 0.5 kHz, and an average of 0.5-4.0 kHz. This study highlights the risk of noise-induced hearing loss among healthcare workers and emphasizes the importance of implementing effective hearing conservation programs in the workplace. Regular monitoring and assessment of noise levels and hearing ability, along with proper use of personal protective equipment, are crucial steps in mitigating the impact of occupational noise exposure on the hearing health of healthcare workers.

Alveolar Bone Morphologic Predictors for Guided Bone Regeneration Outcome in Anterior Maxilla.

OBJECTIVES: This study aimed to explore the influence of alveolar bone morphologic variables on the outcome of guided bone regeneration (GBR) in the anterior maxilla region. METHODS: Twenty-eight patients who received single maxillary anterior tooth delayed implant placed simultaneously with GBR were recruited. Baseline data including age, gender, implant site, implant brand, and bone graft materials were recorded. The resorption rate of the grafted bone (RRGB), labial bone width at 0 mm, 2 mm, and 4 mm apical to the implant platform at Tn (LBW0Tn, LBW2Tn, LBW4Tn), implant angulation (IA), maximum bone graft thickness (MBGT), bone graft volume (BGV), and the initial bone morphologic variables bone concavity depth (BCD) and bone concavity angulation (BCA) were measured. The Pearson correlation analysis, analysis of variance (ANOVA), and optimal binning method were used to explore the potential predictors for GBR. RESULTS: Among 28 patients, the labial bone width of implant and bone graft volume decreased significantly when measured 6 months after surgery. The mean percentage of RRGB was 49.78%. RRGB was not correlated with gender, age, bone graft material, IA, MBGT, bone graft volume at T1, implant site, and implant brand (P > .05). BCD and BCA were each moderately correlated with RRGB (r = -0.872 [P < .001] and r = 0.686 [P < .001], respectively). A BCD ≥1.03 mm and a BCA <155.30° resulted in a significantly lower percentage of RRGB (P < .001). CONCLUSIONS: A significant grafted bone materials volume reduction was detected after GBR with collagen membrane and deproteinized bovine bone mineral (DBBM). The initial bone morphology can influence GBR outcome, and a bone concavity with a depth ≥1.03 mm and an angulation <155.30° led to a lower RRGB. BCD and BCA can be used as variables to predict the outcome of GBR.

Cyclosporine A-induced gingival overgrowth in renal transplant patients accompanied by epithelial-to-mesenchymal transition.

OBJECTIVE: To investigate the association between the prevalence of cyclosporin A-induced gingival overgrowth and the expression of the epithelial-to-mesenchymal transition factors in the gingival tissues of renal transplant patients. BACKGROUND: Gingival overgrowth (GO) is a frequent complication in organ transplant patients treated with the immunosuppressant cyclosporin A (CsA). The epithelial-to-mesenchymal transition (EMT) is considered a factor contributing to CsA-induced GO. However, current knowledge on this topic is sparse. METHODS: Sixty-three renal transplant patients were divided into two groups according to the occurrence of GO: those with gingival overgrowth (GO+ group) and those without gingival overgrowth (GO- group). Data on age, sex, and use of immunosuppressant and calcium channel blocker medications, serum creatinine values, peak concentrations of blood CsA, and gingival hyperplasia scores were recorded to identify clinically pathogenic factors. Gingival tissues from five patients with CsA-induced GO and five healthy subjects were selected for histomorphological observation with hematoxylin-eosin staining, Masson staining, and immunohistochemical staining. The mRNA expression of EMT factors was detected with reverse transcription-quantitative PCR. RESULTS: The use of CsA significantly increased the prevalence of GO in renal transplant patients. The expression of α-SMA, SMAD4, and TGM2 was upregulated and that of E-cadherin was downregulated in the gingival tissues of patients with CsA-induced GO compared with those of the corresponding controls. CONCLUSION: Treatment with CsA is closely related to the occurrence of GO in renal transplant patients and EMT plays an important role in CsA-induced gingival tissue hyperplasia.

A comprehensive finite-element human ear model to estimate noise-induced hearing loss associated with occupational noise exposure.

BACKGROUND AND OBJECTIVE: Noise is a common occupational and environmental hazard; however, little is known about the use of computational tools to quantitively analyze data on basilar membrane (BM) damage in noise-induced hearing loss (NIHL). Here, we established a comprehensive three-dimensional finite-element human ear model to quantify the impact of noise exposure on BM and perilymph fluid. METHODS: We used auditory risk units (ARUs) to evaluate the BM damage for subjects (3 men and 5 women; mean age, 32.75 ± 8.86 years; age range, 24-44 years). A 90-dB sound pressure level (SPL) was normally applied at the external auditory canal (EAC) entrance to simulate sound transmission from the EAC to the cochlea at frequencies of 0.2-10.0 kHz. RESULTS: The pressure distribution of perilymph fluid is totally different on frequency responses under low and high sound-evoked (0.013-10.0 kHz). The highest ARUs were 18.479% at the distance of 1 mm from the base, and the second-highest to fourth-highest ARUs occurred at distances of 5-7 mm from the base, where their ARUs were 9.749%, 9.176%, and 11.231%. The total of the ARUs reached 81.956% at external frequencies' sounds of 3.2-5.0 kHz. Among these, the 3.8-kHz and 3.6-kHz frequencies yielded the highest and second-highest ARUs of 20.325% and 19.873%, respectively. CONCLUSIONS: This study would inform our understanding of NIHL associated with occupational noise exposure. We present a FE modelling and describe how it might provide a unique way to unravel mechanisms that drive NIHL due to loud noises.

Effects of age-related tympanic-membrane material properties on sound transmission in the middle ear in a three-dimensional finite-element model.

BACKGROUND AND OBJECTIVES: The Young's modulus of the tympanic membrane (TM) is an important modeling parameter in computer simulations of the sound transmission in the ear. Understanding the material mechanics of the TM is essential to improve the coupling between the tympanic membrane and the auditory ossicles. However, the impact of the age-related Young's modulus of the TM on sound transmission is not well known. The objective of this study was to use a comprehensive finite element (FE) model to assess the impact of Young's modulus on sound transmission from the ear canal to the stapes footplate over acoustic frequencies. METHODS: The FE model of the ear canal, the middle ear, and the inner ear, was constructed. The model was constructed with identical geometries and boundary conditions, but with three different Young's moduli for the TMs. The auditory ossicles, suspensory ligaments and tendons, and manubrium were also modeled as isotropic elastic materials. Beside, we evaluated the age-related Young's moduli of the TMs on sound transmission with the FE element fluid-structural interaction (FSI) model under acoustic loading conditions. RESULTS: The impact of the age-related Young's moduli on the sound pressure distributions in the ear canal was significant over two frequency ranges of 1.4-3.2 and 8.6-10 kHz. Meanwhile, the significant differences of the displacement of the stapes occurred at around 1.6 kHz, where the displacement of the stapes decreased from 0.352 nm to 0.287 nm. CONCLUSIONS: The FSI model could demonstrate the influence of Young's modulus of the TM on the transfer of sound-induced vibrations form the ear canal to the stapes footplate. The FE model may provide appropriate information to the medical device development of artificial ossicles and hearing aids.

[Characteristics of Nutrient Removal in a Pilot-scale A2/O with Mixture of Sludge Fermentation Liquor and Tail Water as External Carbon Source].

To resolve the issue of sewage fluctuation and discontinuity in a rural district of China, a new operation mode of replenishing the mixture of fermentation liquor and tail water during the off-flow period was proposed, and the nutrient removal performance of a pilot-scale A2/O system with this operation mode was investigated. The results of beaker experiments found that the mixture of tail water and fermentation liquor at a ratio of 12:1 had better denitrification and phosphorus release/absorption characteristics than the raw water, and theoretically had the function of enhancing denitrification and phosphorus removal performances. The results of a 97 d pilot test showed that the removal efficiency of TN and TP was improved after the system was adjusted from the constant flow mode to this new operation mode, and the average removal rate of TN and TP increased from 69.27% and 86.94% to 73.34% and 89.94%, respectively. The corresponding average effluent concentration decreased from 15.77 mg·L-1 and 0.80 mg·L-1 to 13.76 mg·L-1 and 0.64 mg·L-1. The sequencing results of the 16S rRNA gene showed that this new operation mode was beneficial to the enrichment of five common hydrolytic acidizing bacteria genera, six phosphorus-accumulating organisms genera, and four denitrifying bacteria genera. This was also the main reason for the improved nutrient removal performance. According to the long-term monitoring of the characteristics of activated sludge, this new operating mode will degrade the sedimentation performance of activated sludge in the system, and the average SVI increased from 106 mL·g-1 to 131 mL·g-1. However, this degree of deterioration did not adversely affect the sludge activity and nutrients removal performance of the system, and there was no sludge bulking in the entire experiment. The results of this study have shown that the A2/O system can maintain and improve the performance of nutrients removal by replenishing the mixture of tail water and sludge fermentation liquor when the flow is cut off. This will provide new ideas for the design and operation of sewage treatment plants in rural areas in the future.

[Effect of silencing LASP1 on biological behaviors of oral squamous cell carcinoma cells and IC50 of three anti-tumor drugs].

PURPOSE: This study was designed to investigate the effects of LASP1 on proliferation, metastasis, invasion, and cycle of oral squamous cell carcinoma cells and analyze the changes of IC50 in three antitumor drugs: cisplatin, apatinib and docetaxel. METHODS: The correlation between LASP1 and survival rate and prognosis of patients with head and neck cancer were analyzed on the human protein atlas data. RT-PCR and Western blot were used to detect mRNA and protein expression of LASP1 in oral squamous cell carcinoma cell lines. LASP1 silenced HN30 stable transfectant cell line was constructed by lentivirus. CCK-8 assay was used to detect cell proliferation. Plate colony assay was used to detect cell clone formation ability. Transwell assay was used to detect cell migration and invasion ability. Flow cytometry was used to detect cell cycle changes. Oral squamous cell carcinoma metastases were established in nude mouse, the number of metastatic lung nodules was counted and stained with H-E. CCK-8 method was used to analyze the changes of IC50 in three antitumor drugs: cisplatin, apatinib and docetaxel. Statistical analysis was performed using SPSS 11.0 software package. RESULTS: LASP1 was closely related to the survival rate and prognosis of head and neck cancer. LASP1 promoted proliferation, colony formation, metastasis and invasion of oral squamous cell carcinoma cell line HN30, promoted G2/M phase transition of cell cycle, and significantly reduced the formation of lung metastasis in nude mice after silencing. There was significant correlation with docetaxel IC50 but no significant impact on cisplatin IC50 and aptatinib IC50. CONCLUSIONS: LASP1 enhances cell proliferation, plate cloning, metastasis and invasion, G2/M phase transition of cell cycle, promotes lung metastasis in nude mice and docetaxel resistance of oral squamous cell carcinoma cell line HN30.

[Treatment of combined periodontal-pulpal lesions with periodontal therapy].

PURPOSE: To evaluate the clinical effects of periodontal therapy for combined periodontal-pulpal lesions. METHODS: One hundred and nine patients with periodontal-pulpal lesions were included in this study, with total 120 teeth. All the teeth were treated by perfect root canal therapy, and than divided into group A and B. Group A was treated with periodontal therapy (60 teeth). After 2 weeks of root canal therapy, basic periodontal therapy was performed. After 6 weeks, patients with more than 5 mm periodontal pockets and bleeding after probe were treated with valvuloplasty. Group B underwent non-periodontal treatment (60 teeth), root canal therapy and supragingival scaling alone. The patients were followed up for 3, 6, 12 and 24 months after operation. SPSS 22.0 software package was used to analyze the indexes at initial diagnosis and 24 months after operation. RESULTS: In group A, the depth of periodontal pockets was significantly reduced before and after PD, from(5.966±1.877) mm to(5.133±1.935) mm. The periodontal pocket depth of group B was significantly increased before and after operation, from(5.533±1.856) mm to (6.167±1.927) mm. The degree of tooth mobility (TM) before operation was similar between the two groups (P>0.05). Two years after operation, the degree of TM in group A was significantly lower than that in group B (P<0.05). There was no significant change in alveolar bone resorption before and after operation in group A (P>0.05). The alveolar bone resorption in group B changed significantly before and after operation (P<0.05). CONCLUSIONS: Root canal therapy combined with periodontal therapy for combined periodontal-pulpal lesions can achieve good results. It can be widely used in clinic.

[Clinical study of simultaneous implantation in maxillary molar area after bone graft in patients with residual alveolar bone height<3 mm].

PURPOSE: To evaluate the clinical effect of maxillary sinus floor elevation and simultaneous implant in patients with residual alveolar bone height <3 mm in the posterior maxillary sinus area. METHODS: From April 1, 2012 to December 31, 2015, 56 patients with lost maxillary posterior teeth and residual alveolar bone height <3 mm were enrolled in this study. During operation, maxillary sinus floor elevation was performed and implants were placed simultaneously. Patients were followed up for 3, 6 and 12 months (range: 6-12 months) to analyze and evaluate the postoperative healing effect. RESULTS: A total of 52 implants were placed in 38 patients. During the follow-up period, all patients had good osterintegration of the implants and the surrounding bony tissues. Efficient mastication was obtained. The color and shape of gingiva returned to normal. No complications occurred. The surgical success rate was 100%. CONCLUSIONS: For patients with residual alveolar bone height <3 mm, maxillary sinus floor elevation and simultaneous implant in patients can also obtain good therapeutic effect.

[The effect of C-SiO2 composite films on corrosion resistance of dental Co-Cr alloy].

PURPOSE: To study the effect of carbon-silica composite films on corrosion resistance of Co-Cr alloy in simulated oral environment and provide evidences for clinical application of this new material. METHODS: Co-Cr alloy specimens were cut into appropriate size of 20 mm × 20 mm × 0.5 mm. Then, the carbon-silica composite films were spin-coated onto the specimens. Subsequently, ICP-AES was used to observe the Co, Cr, Mo ion concentrations. Finally, Tafel polarization curves of the specimens were used to measure the electrochemical corrosion resistance by electrochemical workstation. SAS8.0 software package was used for statistical analysis. RESULTS: The results of ICP-AES showed that the ion concentrations of Co, Cr, Mo of specimens coated with composite films in the testing liquid were significantly smaller than that of Co-Cr alloy specimens. Tafel polarization curves showed that in the specimens coated with composite films, the corrosion potential moved in the positive direction and increased from -0.261 V to -0.13 V. At the same time, the corrosion current density decreased from -5.0017µA/cm2 to -5.3006 µA/cm2. CONCLUSIONS: Carbon-silica composite films (silica=61.71wt %) can reduce the release of metal ions significantly and improve the corrosion resistance of Co-Cr alloys effectively. Carbon-silica composite films may be a promising dental material.