Preparation of an amino hybrid mesoporous silica-based nanotopography protective coating on a titanium implant surface and evaluation of its osteogenic effect / 口腔疾病防治

Objective@#To deposit degradable amino-hybrid mesoporous silica (AHMS) in situ on the surface of titanium nanotube (TNT) and explore its protective effect on nanomorphology and osteogenesis.@*Methods@#TNT and TNT@AHMS were sequentially prepared via an anodizing method: the oil-water two-phase method (experimental group) and the acid-etched titanium method [control group (Ti)]. The parameters for synthesis were explored by changing the silicon source dosage ratio (3∶1, 1∶1, 1∶3); the surface morphology was observed by scanning electron microscope(SEM), hydrophilicity was detected by Water Contact Angle Tester, elemental composition was detected by X-ray photoelectron spectroscopy (XPS); nanoindentation test and ultrasonic oscillator were used to observe the morphological holding effect as mechanical strength of TNT@AHMS in vitro; simulated immersion experiments in vitro was used to observe the degradation behavior of the material. the MC3T3-E1 cell line was used to observe the effect of cell adhesion, proliferation and differentiation on the material; and an SD rat femoral implant model and micro-CT were used to verify the protective effect and osseointegration effect of AHMS on TNT morphology.@*Results@#The morphologies of TNT and TNT@AHMS were successfully prepared, and the silicon source ratio was 1:3. SEM showed that the titanium nanotubes were uniformly covered with AHMS coating, and the mesoporous pore size was about 4 nm. After AHMS was incorporated, the surface of the material was hydrophilic (12.78°), the presence of amino groups (NH2-) was detected, the material was completely degraded within 12 h in vitro, and the active morphology of the TNT was re-exposed with a cumulative silicon release of 10 ppm. Nanoindentation test showed that TNT@AHMS exhibited more ideal surface mechanical strength. SEM revealed that TNT maintains its own morphology under the protection of AHMS, and the TNT group suffered severe exfoliation. In addition, the early adhesion and proliferation rates, ALP activity, and bone volume fraction of cells on the TNT@AHMS surface 4 weeks after implantation were significantly higher than those in the TNT group.@*Conclusion@#By depositing AHMS on the surface of TNT, the nanotopography can be protected. It not only prevents the active base topography from exerting subsequent biological effects but also further endows the material with the ability to promote bone regeneration, laying a foundation for the future development of nanotopography-modified titanium implants.

Application and comparison of three risk assessment methods for occupational health risk assessment of dust in a sanitary ceramic product manufacturing enterprise / 上海预防医学

ObjectiveThree methods were applied to conduct occupational health risk assessment for the working positions exposed to silicon dusts in a sanitary ceramic manufacturing factory， and the evaluation results were compared to explore the applicability of different occupational health risk assessment methods. MethodsOne large sanitary ceramic product manufacturing enterprise in Songjiang District， Shanghai was selected to conduct occupational health risk assessment for the working positions exposed to silicon dusts， using occupational hazard risk index evaluation method， exposure ratio evaluation method， and International Council on Mining and Metals （ICMM） quantitative occupational health risk assessment method . The consistency of the evaluation results of the three methods was tested using weighted Kappa method. ResultsFourteen working positions exposed to silicon dusts were identified， and three positions had excessive dust concentration： composite forming position of phase 2 workshop （0.80 mg·m-3）， addition forming position of phase 2 workshop （1.00 mg·m-3）， and glazing position of 1F in phase 2 workshop （1.50 mg·m-3）， with an excessive rate of 21.42%. The occupational hazard risk index evaluation method assessed 6 positions with no harm， 6 positions with mild harm， and 2 positions with moderate harm. The ICMM quantitative occupational health risk assessment method assessed 6 positions with potential risks， 2 positions with tolerable risks， and 6 positions with intolerable risks. The exposure ratio evaluation method assessed 8 positions with medium risk， 5 positions with high risk， and 1 position with extremely high risk. The consistency test results of the three evaluation methods were poor. The Kappa coefficient between the occupational hazard risk index evaluation method and the ICMM quantitative occupational health risk assessment method was 0.15. The Kappa coefficient between the occupational hazard risk index evaluation method and the exposure ratio evaluation method was -0.09. The Kappa coefficient between the ICMM quantitative occupational health risk assessment method and the exposure ratio evaluation method was 0.04. The RR values obtained by the three evaluation methods were significantly correlated： the correlation coefficients between RRICMM quantitative assessment method and RRexposure ratio evaluation method， RROccupational hazard risk index evaluation method and RRICMM quantitative assessment method， RROccupational hazard risk index evaluation method and RRexposure ratio evaluation method were 0.915， 0.604， and 0.594， respectively. The correlation between the assessment result level and CTWA was strong. ConclusionThe occupational hazard risk index evaluation method is suitable for the working positions with low silicon dust exposure concentration， the ICMM quantitative occupational health risk assessment method and the exposure ratio evaluation method are suitable for the positions with high silicon dust exposure concentration， but all these three evaluation methods have limitations. It is more reasonable to use multiple methods at the same time in actual evaluation work.

Development and performance test of unmanned aerial vehicle-borne CeBr3 radiation monitoring system / 中国辐射卫生

Objective To develop an unmanned aerial vehicle (UAV)-borne radiation monitoring system with high detection efficiency and nuclide identification ability for airborne monitoring in nuclear emergency. Methods The UAV-borne CeBr3 radiation monitoring system was composed of four cerium bromide (CeBr3) crystal detectors coupled with silicon photomultipliers (SiPMs) and other components including integrated modules, intelligent electronic devices, and new composite materials. Results According to various performance tests on the system, the crystal energy resolution was better than 5% (@0.662 MeV), the peak drift of the energy spectrum was within ±1 channel, the linear fit of energy was 0.99997, the change in the count rate of each energy window during 12 h long-term measurement was less than 5%, and the detection efficiency was higher compared with that of NaI (Tl) detectors of the same volume. Conclusion Through ground point source testing and theoretical calculation, the system has reliable ability to identify radionuclides, which can be used in nuclide identification and the preparedness and response for nuclear and radiation emergencies.

Resin cast in situ: A technique to demonstrate the vasculature of the Nervous system: In Goat Model

Background: As Anatomical education advances very rapidly, and at the same time, there is huge demand and scarcity of true biological models, mainly brain tissue. In this scenario, in 1977, Guther Von Hagens worked on plastics and experimented voraciously on diffusing various plastics into large specimens and ultimately succeeded and coined the term “Plastination”. This technique is very popular in Western countries as the latter greatly minimizes the health hazards due to formalin exposure while dealing with biological tissue. In continuation with the advancement of expensive plastination to cost-effective resin casting, especially studies over the complex structures like the brain and spinal cord. In This study, we emphasize the cost-effective Resin cast-insitu method to demonstrate the vasculature of the brain and spinal cord. Materials and Methods: After obtaining the prior permission, we collected the Five (5) Goat heads from the slaughterhouse. Following the standard dissection procedure over the neck region, identified and canulated the major neck vessels. Through the vessels normal saline water, formalin, and pigmented resin were administered and preserved the goat head using routine preservation technique. After 36 to 48 hours, the routine dissection was scheduled to expose the brain and upper spinal cord segments, and finding were captured and recorded. Results and Discussion: The specimens show good penetration of dye in the artery and veins, and it’s easy to appreciate and study the vasculature of the brain and upper spinal cord segments, including the Bastons plexus of veins. Conclusion: In comparison with regular silicon casting, resin casting is very cost-effective and long-lasting, with good penetration of the resin substance up to the capillary level. Furthermore, similar studies may be conducted using in combination with whole organ plastination using silicon and resin embedding.

Effect of Soil and Climatic Conditions on Brown Spot Occurrence in Rice Lowland across Four Agro-climatic Zones of Côte d’Ivoire

Aims: To evaluate interaction of soil pH and acidity with weather on Rice Brown spot (BS) occurrence in rice lowlands. Study Design: Cross sectional study. Place and Duration of Study: Four distinct rice lowlands belonging to different climatic zones (forest, transitional and savanna) of Côte d’Ivoire during cropping seasons of 2021. Methodology: BS characterization were done in different farmer fields where soil samples were also collected during dry and rainy seasons. Soil silicon and acidity were determined in those samples and rice grain yield at harvest time were recorded in different sites. Weather data related to sites and seasons were used to find out correlations. Results: Occurrence of BS was found in forest zones with scores of 4 and 3 compared to 1 and 2 in savanna and transitional zones, respectively, with seasonal variation. Both rice production and the occurrence of BS were explained by soil parameters in conjunction with climatic parameters. Rainfall (R=0.38) and relative humidity (R=0.64) leaded BS occurrence and decrease of yield. Wind speed (R=0.62) and air maximum temperature (R= 0.63) were the determinant factors affecting rice yields. Si was found to be a component of sustainable soil management that interferes with soil pH in all climatic zones. Combined with Temperature, both soil parameters predicted BS occurrence over 50%. Conclusion: Temperature decrease BS pathogens occurrence whereas high humidity increases its spread. Those parameters combined with silicon which interferes with pH could leads sustainable solutions in BS control. Furthermore, having a deep understanding with rice varietal considerations can significantly improve strategies related to rice cultivation and protection.

Safe duration of silicon catheter replacement in urological patients

Objectives: This study compared the infection rates, degree of encrustation, symptoms, and complications in patients regarding the duration of urethral catheterisation (three weeks, six weeks, and eight weeks). Design: A cross-sectional study with stratified simple random sampling Setting: Urology Unit, Korle Bu Teaching Hospital Participants: One hundred and thirty-seven male patients with long-term urinary catheters Interventions: Participants were grouped into 3 weeks, 6 weeks, and 8 weeks duration of catheter replacementsPrimary outcomes measures: Symptoms due to the urinary catheters, urinalysis, urine and catheter tip cultures, sensitivity, and catheter encrustations were assessed. Results: Eighty-six patients had a primary diagnosis of benign prostatic hyperplasia (BPH), 35 had urethral strictures,13 had prostate cancer, two had BPH and urethral strictures, and one participant had bladder cancer. There was no difference in the symptoms the participants in the different groups experienced due to the urinary catheters (p > 0.05). The frequency of occurrence of complications (pyuria, p = 0.784; blocked catheter, p=0.097; urethral bleeding, p=0.148; epididymo-orchitis, p=0.769 and bladder spasms, p=1.000) showed no differences in the three groups. There was no statistical difference in the urinalysis for the three groups (p>0.05) and the degree of encrustations (3 weeks: 0.03 ± 0.06, 6 weeks: 0.11±0.27 and eight weeks: 0.12 ±0.27) with p=0.065. Conclusions: In this study, the duration of urinary catheterisation using silicone Foley's catheters did not influence the complication and symptom rates; hence silicon catheters can be placed in situ for up to 8 weeks before replacement instead of the traditional three-weekly change.

Effects of fiber surface deposited with silicon dioxide films on properties of fiber-reinforced composites / 口腔医学

Objective@#To investigate the effects of fiber surface deposited with silicon dioxide films by atomic layer deposition on properties of dental fiber-reinforced composites.@*Methods @#SiO2 films were deposited on the surface of quartz fiber by atomic layer deposition(ALD). Then the quartz fiber was used to manufacture fiber resin composites, which were divided into four groups: A(no soaking agent removal), B(soaking agent removed), C(soaking agent removed and silanization), and D(soaking agent removed, 600 ALD cycles performed and then silanization). Scanning electron microscopy, water contact angle test, hygroscopicity test, CCK8 test and three-point bending test were used to investigate the properties of fiber resin composites.@*Results@#The surface morphology of the quartz fiber treated by ALD was smooth and had no obvious change compared with that before treatment. Moreover, the quartz fiber showed hydrophobicity after silanization. The results of three-point bending test revealed that the mechanical properties of fiber-resin composites modified by ALD were significantly improved(P<0.05). When viewed by scanning electron microscopy, a good interfacial bonding could be seen between quartz fibers and the resin matrix in Group D. In addition, it was found that Group D had low absorbability, low solubility and good biocompatibility. @*Conclusion@#It is shown that deposition of SiO2 films on the quartz fiber by ALD can significantly enhance the mechanical properties of fiber-reinforced composites.

Preparation and evaluation of sirolimus sustained release tablets based on mesoporous silicon loaded self-microemulsion / 药学学报

Sirolimus self-microemulsion-mesoporous silicon sustained release tablets were prepared in order to improve the dissolution of the insoluble drug sirolimus and reduce its side effects. Firstly, sirolimus self-microemulsion was prepared and cured with mesoporous silicon. Secondly, the suitable excipients were selected according to the appearance, hardness and in vitro release rate. The sustained-release tablets with hydroxypropyl methylcellulose (HPMC) as skeleton material were prepared by powder direct pressing method, and the formulation was optimized by central composite design-response surface method to investigate the drug release in vitro. Finally, the pharmacokinetics was carried out in beagle dogs using the commercial sirolimus tablets as references. The final formulation of sustained-release tablets is as follows: 162 mg of sirolimus self-microemulsion-mesoporous silica (1∶1, w/w), 80 mg of HPMC K4M and 80 mg of carboxymethyl starch sodium, the microcrystalline cellulose is 168 mg. The results of in vitro release test showed that the self-made sustained-release tablets released slowly within 12 h, which conformed to the Ritger-Peppas model. The in vivo test results showed that compared with the commercial sirolimus tablets, the Cmax of the sustained-release tablets decreased by 49.47%, the Tmax of the sustained-release tablets was prolonged by 5.1 times, and the relative bioavailability was 105.81%. Sirolimus self-microemulsion-mesoporous silicon sustained-release tablets have good sustained-release effects in vitro and in vivo, which provides a reference for the solubilization of other insoluble drugs and the research and development of sustained-release preparations. Animal experiments and welfare processes were reviewed and approved by the Animal Ethics Committee of the 900TH Hospital of the Joint Logistics support Force.

Research on friction and wear behaviors of silicon-lithium spray coating on zirconia ceramics / 北京大学学报(医学版)

OBJECTIVE@#To study microstructure, friction and wear behaviors of silicon-lithium spray coating on the surface of zirconia ceramics and to preliminarily evaluate its esthetic so as to provide support and guidance for the clinical application.@*METHODS@#Zirconia ceramic specimens were randomly divided into three groups: coating group (two subgroups), polishing group (two subgroups), and glazing group (four subgroups), with 10 samples in each subgroup. The two subgroups of coating group were the zirconia ceramics with the untreated and preliminary polishing surfaces sprayed with silicon-lithium coating, respectively. The two subgroups of polishing group were preliminary polishing and fine polishing of zirconia ceramics, respectively. The four subgroups of glazing group were preliminarily polished zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively; and untreated zirconia ceramics glazed with Biomic and Stain/Glaze products, respectively. The above 8 subgroups of zirconia ceramic specimens were used as friction pairs with 80 steatite ceramics for 50 000 chewing cycles under 50 N vertical load and artificial saliva lubrication using chewing simulation. Scanning electron microscope was used to observe the microstructure of the surface and section of the coating group, and the thickness of the coating and glazing were measured. The linear roughness of the coating and polishing groups was mea-sured using a laser confocal scanning microscope. Vickers hardness was measured using a microhardness tester and the esthetic of zirconia ceramic full crown sprayed with silicon-lithium coating was preliminarily evaluated. White light interferometer was used to measure the width, the maximum depth and the volume of the wear scars of each group, and the wear depth of steatite ceramics and wear rate of zirconia ceramic specimens were calculated. Kruskal-Wallis nonparametric test and Dunn's multiple comparisons test were used to analyze the wear depth of each group (α=0.05).@*RESULTS@#The microstructures of the silica-lithium spray coatings on the untreated and preliminarily polished zirconia ceramic surfaces showed the protruding defects, and the line roughness of coating group was larger than that of the polishing group. The median thickness of the silica-lithium spray coating on the preliminarily polished zirconia ceramic was 13.0 μm (interquartile range, IQR: 11.6, 17.9), while that of the silica-lithium spray coating on the untreated zirconia ceramic was 4.4 μm (IQR: 4.1, 4.7). The Vickers hardness and wear rate of the coating group were between the polishing group and the glazing group. The wear depths of the wear scars of steatite ceramics were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference between glazing and polishing groups (P < 0.05). With the increase of polishing procedure, the wear depth of steatite ceramics decreased in each subgroups. The orders of maximum depth and volume of wear scars of zirconia ceramic were the glazing group, coating group, and polishing group in descending order, and there was statistically significant difference in the maximum depth of wear scars between glazing and polishing groups (P < 0.05).@*CONCLUSION@#The silica-lithium spray coating on the zirconia ceramic, can be used as a new method for zirconia ceramic surface treatment, because it can increase the esthetic of zirconia ceramics compared with polishing and reduce the wear of steatite ceramics compared with glazing.

Cleansing effect of NO sustained-release silica nanoparticles on endoscopic biofilm and its clinical application / 中华消化内镜杂志

Objective:To explore the cleansing effect of Nitric Oxide (NO) sustained-release silica nanoparticles (short for NO sustained-release agent) on endoscopic biofilm and its clinical application.Methods:A total of 160 clinical endoscopes were randomly divided into two groups: the cleansing agent group (80 pieces, disinfected with cleansing agents), NO group (80 pieces, disinfected with NO sustained-release agent). A biofilm model of Pseudomonas aeruginosa was constructed and used as the control for phosphate buffered solution (PBS) treatment. A biofilm model of Pseudomonas aeruginosa on the surface of endoscopic lumen was built first in vitro. Scanning electron microscopy was then used to observe the microstructure of biofilm after treatment with NO sustained-release agent. Viable counting method was used to evaluate the cleansing effect of NO sustained-release agent on biofilm. Finally, at the clinical level, the actual disinfection effect of NO sustained-release agent on clinical endoscopy was evaluated by detecting the protein residues, viable counting and adenosine triphosphate (ATP) biofluorescence detection. Results:The scanning electron microscopy showed that the biofilm was intact in the model group, but scattered bacteria were observed on the biofilm surface in the NO group and the detergent group. Compared with the model group [(4.86±2.67)×10 6(colony-forming units, CFU)/mL], the standard CFUs of the NO group [(1.37±0.61)×10 4CFU/mL] and the detergent group [(1.31±0.21)×10 5CFU/mL] were significantly lower (detergent group VS model group, P=0.009; NO group VS model group, P=0.008), and there was significant difference between the detergent group and the model group ( t=9.53, P=0.000 6). The levels of residual proteins in the endoscopic lumens before and after the treatment were 8.03±1.47 mg/mL and 0.50±0.37 mg/mL in the NO group, 8.01±1.51 mg/mL and 0.91±0.52 mg/mL in the detergent group with significant difference ( P<0.01), and the reduction effect of the NO group was more significant. The disinfection of NO group and cleaning agent group was within the qualifying range, but the ATP bioluminescence value, protein residue and colony count of NO group (78.56±42.59 RLU, 0.50±0.37 mg/mL, 7.55±4.56 CFU) were significantly lower than those of detergent agent group (120.80±54.00 RLU,0.91±0.52 mg/mL,11.50±4.75 CFU, P<0.01). Conclusion:NO sustained-release agent can effectively clear endoscopic biofilm and further improve the disinfection effect on endoscopes, which may be of great significance for improving the effects on treatment and prognosis of patients.

Effect of silicon dioxide exposure on airway surface microenvironment and NEK7/NLPR3 inflammasome in rats / 预防医学

Objective@#To examine the effect of SiO2 exposure on the airway surface microenvironment and NIMA-related kinase 7 (NEK7)/nucleotide-binding oligomerization domain-like receptor containing pyrin domain 3 (NLRP3) inflammasome in rats.@*Methods@#Twenty-four specific pathogen-free male rats of the SD strain were randomly divided into the control group and the model group, of 12 rats in each group. Rats in the model group were given SiO2 suspensions through disposable tracheal intubation perfusion to model silicosis in rats, while rats in the control group was perfused with the same amount of physiological saline. The pH value and glucose level were measured in the rat bronchoalveolar lavage fluid (BALF) 14 and 28 days after modeling. Lung tissues were stained with HE and Masson and the distribution of inflammatory cells and the deposition of pulmonary interstitial collagens were observed in lung tissues under a light microscope. The expression of transforming growth factor β1 (TGF-β1), collagen type Ⅰ(ColⅠ), collagen type Ⅲ (Col Ⅲ), interleukin-1β (IL-1β), NLRP3, N-terminal domain of Gasdermin D (GSDMD-NT), caspase-1, and NEK7 was quantified in lung specimens using immunohistochemistry.@*Results@# Lower pH values were measured in rat BALF in the model group than in the control group 14 [(6.38±0.05) vs. (6.68±0.08), P<0.05] and 28 days after modeling [(6.63±0.14) vs. (6.86±0.05), P<0.05], while higher glucose levels were seen in the model group than in the control group 14 [(0.39±0.06) vs. (0.31±0.04) mg/dL, P<0.05] and 28 days after modeling [(0.39±0.08) vs. (0.31±0.06) mg/dL, P<0.05]. HE and Masson staining showed mild to moderate alveolitis and pulmonary fibrosis in rats 14 days post-exposure to SiO2, and showed moderate to severe alveolitis and pulmonary fibrosis 28 days post-exposure. Immunohistochemistry detected higher TGF-β1, ColⅠ, Col Ⅲ, IL-1β, NLRP3, GSDMD-NT, caspase-1 and NEK7 expression in rat lung tissues in the model group than in the control group (all P<0.05). @*Conclusions@#SiO2 exposure may cause changes in rat airway surface microenvironment, including BALF acidification and elevated glucose. Pyroptosis induced by activation of NEK7-associated NLRP3 inflammasome may be an important mechanism of pulmonary fibrosis caused by silicosis.

Bilateral frontalis sling for surgical correction of unilateral and bilateral severe congenital ptosis with poor levator function

Objective@#This study evaluated the functional and cosmetic outcomes after bilateral frontalis sling repair using either expanded polytetrafluoroethylene (ePTFE) or silicone rod for unilateral or bilateral severe congenital ptosis with poor levator function.@*Methods@#This was a non-comparative, interventional case series involving 30 patients with unilateral or bilateral severe congenital ptosis who underwent bilateral frontalis sling repair from February 2012 to November 2018. Medical records including pre- and postoperative photographs were reviewed. The functional and cosmetic outcomes were assessed.@*Results@#There were 15 patients with severe congenital ptosis who underwent ePTFE surgery and 15 patients who had silicone rod surgery. Baseline levator function measured was less than 5 mm in all patients. The mean follow-up duration after surgery was 15.6+6.9 months. Satisfactory eyelid contour was observed in all patients (100%). Postoperatively, all had good to excellent primary eyelid position and effective frontalis action on eyelid elevation. Complications included exposure of the silicone sling material after trauma at the brow area (n=1) and recurrence of ptosis (n=2).@*Conclusion@#Bilateral frontalis suspension in patients with severe congenital ptosis, whether bilateral or unilateral, resulted in excellent functional and cosmetic outcomes using ePTFE or silicone rod.

When the savior becomes a demon: Silicon oil synechia-induced glaucoma

Background: Silicon oil is an important adjunct for achieving internal tamponade in the treatment of retinal detachment. Silicone oil tamponade often leads to narrowing of the angle and development of adhesions between the iris and anterior chamber angle structures, with consequential elevation of the intraocular pressure. The video showcases the management of these challenging scenarios. Purpose: To highlight the management of early synechial closures due to silicon oil tamponade. Synopsis: The video highlights the management of early synechial closure following silicon oil tamponade. Surgical pupilloplasty has been demonstrated to break the peripheral anterior synechias on intraoperative gonioscopy as well as on anterior segment optical coherence tomography (AS?OCT). Performing pupilloplasty in the early phase of development of peripheral anterior synechias (PAS) helps to break the existing synechias and prevent angle closure and sequential deterioration of vision. Highlights: Surgical pupilloplasty helps to relieve the post silicon oil?induced secondary angle closure glaucoma by breaking the peripheral anterior synechias and significantly opening the anterior chamber angles.

Evaluation of biofilm formation on acrylic resin surfaces coated with silicon dioxide: an in situ study

Abstract Biofilm on acrylic resin dental prostheses may cause gingival inflammation. This study evaluated the influence of a silicon dioxide coating layer applied onto acrylic resin on the adhesion of microorganisms. Blocks (5 x 5 x 3 mm) of acrylic resin were evaluated for surface roughness and divided into two groups: control (CG) and coated with silicon dioxide (LG group). The specimens were evaluated by scanning electron microscopy (n = 1) and by contact angle analysis (n = 3). For the in situ study, 20 volunteers wore acrylic palatal devices containing three samples from each group (n = 60) for 2 days. The biofilm formed was quantified by metabolic activity and total biomass using the crystal violet assay. The results were subjected to Bartlett's normality test and Gamma model with random effect for the response variable (α = 5%). The mean contact angle of the coated group was significantly lower than that of the uncoated group (p < 0.05). The metabolic activity of microorganisms in the biofilm on the blocks treated with coating was significantly lower than that of control blocks (p = 0.02). Regarding the amount of extracellular matrix produced by the microorganisms, there was no difference between the CG and LG group (p = 0.05). The application of a silicon dioxide coating on acrylic resin reduced the activity of the polymicrobial biofilm formed in situ. This coating may be advantageous for patients with conventional complete dentures or implants made of acrylic resin and who have motor difficulties that prevent them from cleaning their prostheses properly.

Effect of miR-204 targeted regulation of DVL3 gene in silica-induced mouse lung epithelial cells / 中华劳动卫生职业病杂志

Objective: To construct a recombinant lentiviral vector for mouse miR-204 overexpression, and to verify the targeted regulation of miR-204 and DVL3 in silica (SiO(2)) -induced mouse lung epithelial cells (MLE-12 cells) . Methods: In October 2019, the pre-miR-204 gene was amplified from the mouse genome by the polymerase chain reaction (PCR) method. After sequencing, the amplified product was cloned into the pLenti-CMV-EGFP lentiviral vector. The positive clones were identified by PCR screening and sequencing. The miR-204 overexpressed lentiviral vector was transfected into 293T cells, and lentiviral packaging and titer determination were performed. The experiment was divided into SiO(2) control group, virus control group, and miR-204 virus group, and the expressions of miR-204 and DVL3 gene were detected by real-time PCR. Results: The miR-204 lentiviral expression vector Lv-miR-204-5p was constructed and identified correctly by PCR and sequencing, and a virus dilution with a titer of 9.57×10(8) IU/ml was obtained. The results of real-time PCR showed that the expression of miR-204 in MLE-12 cells of the miR-204 virus group was higher than that of SiO(2) control group and virus control group, and the expression of DVL3 gene was lower than that of SiO(2) control group and virus control group, the differences were statistically significant (P<0.05) . Conclusion: Overexpression of miR-204 by lentiviral vector may inhibit the expression of DVL3 gene in silica-induced mouse lung epithelial cells.

Application prospect of silicon nitride ceramics in dental implants / 口腔疾病防治

@#Silicon nitride has high fracture toughness and compressive strength similar to human bone. It meets the basic mechanical requirements of implants and has good biocompatibility. The micrometer/nanometer morphology surface characteristics of silicon nitride give it good osteogenic activity and antibacterial properties, which are helpful to reduce the incidence of periimplant inflammation. Therefore, silicon nitride has good application potential in dental implants. In orthopedics, silicon nitride implants have been used in spine repair and joint implantation. However, there is a lack of research on silicon nitride as dental implant material. The evaluation of the osteogenic and antibacterial properties of silicon nitride bioceramics prepared using different sintering additives and sintering processes, the antibacterial properties of silicon nitride on different dominant oral pathogens, and the osteogenic activity and antibacterial properties of silicon nitride materials implanted into the jaw need to be further studied. Combined with the latest research results at home and abroad, this review discusses the application potential of silicon nitride materials in dentistry.

The role of TSG-6 in inhibiting the secretion of IL-1β by bone-marrow-derived macrophages / 中国职业医学

@#Objective To investigate the role of tumor necrosis factor alpha stimulated gene/inducible protein 6（TSG-6）on free silica（SiO2 ）-induced secretion of pro-inflammatory cytokine interleukin（IL）-1β by bone-marrow-derived macrophages （BMDMs）. Methods i）BMDMs isolated from bone marrow were divided into eight groups：the control group was untreated； lipopolysaccharide （LPS） group was stimulated by LPS with a concentration of 50 µg/L；The TSG-6 control group was stimulated by 100 µg/L of recombinant mouse TSG-6. SiO2 model group was pre-stimulated with LPS for four hours，and then stimulated with SiO2 suspension at a final concentration of 250 mg/L；Different dose of TSG-6 groups were firstly treated with above concentrations of LPS and SiO2 suspension，then 10，20，50 and 100 µg/L of recombinant mouse TSG-6 were added respectively；After 16 hours of culture，the cells were collected and the level of IL-1β in BMDMs supernatant was detected by enzyme-linked immunosorbent assay（ELISA）to screen optimal concentration of TSG-6. ii）The cells of the control group，LPS group，SiO2 model group，TSG-6 optimal concentration group and TSG-6 control group were collected. The expression of IL-1β and components of its related pathways in BMDMs was detected by Western blot，including IL-1β，pro-IL-1β，caspase-1，pro dcaspase-1，asc type amino acid transport and NOD-like receptor protein 3（NLRP3）. Results i）Compared with the control group，the expression of IL-1β in SiO2 model group was increased significantly（P<0.01）. Compared with SiO2 model group，the expression of IL-1β in 20，50，100 µg/L dose of TSG-6 groups were decreased significantly（all P<0.01），and the optimal concentration of TSG-6 was found to be 100 µg/L. ii）Compared with the control group and LPS group，the relative expression levels of IL-1β，caspase-1 and NLRP3 in SiO2 model group were increased significantly （all P<0.05）. Compared with SiO2 model group，the expression levels of IL-1β、caspase-1 and NLRP3 were decreased in 100 µg/L TSG-6 group（all P<0.05）. Conclusion TSG-6 could inhibit BMDMs to secret pro-inflammatory cytokine IL-1β by down-regulating the expression of NLRP3 and caspase-1.

Effects of silicon dioxide exposure on lipid deposition and PI3K/AKT/mTOR signaling pathway in MLE-12 cells / 环境与职业医学

Background Lipid metabolism imbalance is tightly linked to the development and progression of multiple diseases. The phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway is important for the regulation of lipid metabolism. However, whether silicosis is associated with lipid metabolic abnormalities has yet to be explored. Objective To observe the changes of lipid deposition, cholesterol, and phosphorylated proteins of PI3K/AKT/mTOR pathway in silicon dioxide (SiO2)-induced MLE-12 cells and to explore potential mechanism of lipid composition regulated though the pathway. Methods (1) MLE-12 cells were stimulated with 50 mg·L−1 SiO2 suspension, and divided into fourgroups: a control group and three SiO2 groups (12, 24, and 48 h of stimulation). (2) Cellproliferation was detected to determine an optimal dose of LY294002, an inhibitor of PI3K protein. LY294002 at 5 μmol·L−1 was used for further study, in which MLE-12 cells cultured for 48 h were divided into four groups: a control group; a 50 mg·L−1 SiO2 suspension stimulation group; a 50 mg·L−1 SiO2 suspension and 5 μmol·L−1 LY294002 treatment group; a 5 μmol·L−1 LY294002 treatment group. Total cholesterol (TC), free cholesterol (FC), cholesterol ester (CE; total cholesterol minus free cholesterol), and triglycerides (TG) were measured with enzyme assay kits. Lipid deposition was observed using Oil Red O staining. The expressions of p-PI3K, p-AKT, and p-mTOR proteins were detected by Western blotting. Results (1) The contents of TC, FC, and CE in the 50 mg·L−1 SiO2-induced MLE-12 cells were increased compared to those of the control group in a time-dependent manner by trend analysis, and the increment at 24 and 48 h were significant. By 48 h, the contents of cholesterol indicators were all elevated: TC from (2.242±0.181) mg·g−1 to (5.148±0.544) mg·g−1, FC from (1.923±0.158) mg·g−1 to (4.168±0.433) mg·g−1, and CE from (0.318±0.067) mg·g−1 to (0.978±0.134) mg·g−1, compared with the control group (P<0.01). The changes of TG were not significant (P>0.05). The SiO2 suspension induced orange-red particle deposition in the MLE-12 cells, especially at 48 h (P<0.01). The protein expression levels of p-PI3K, p-AKT, and p-mTOR in SiO2-stimulated MLE-12 cells were higher than those of the control groups with the prolongation of stimulation time, which peaked at 48 h (P<0.01). (2) The contents of TC, FC, and CE in MLE-12 cells of the SiO2 + LY294002 group were decreased, comparing to those of the SiO2 stimulation only group (P<0.01), companied with less orange-red lipid deposition, and suppressed protein expression levels of p-PI3K, p-AKT, and p-mTOR (P<0.01). Conclusion SiO2 could induce increases of cholesterol and lipid deposition through activation of PI3K/AKT/mTOR signaling pathway in MLE-12 cells.

Eficacia del cementado indirecto / Indirect bonding efficiency

La aparición de aparatología preadjustada ha colaborado en la efectividad de los tratamientos de ortodoncia, pero para que la expresión de esta aparatología se logre, es necesario una correcta colocación de los brackets y la permanencia de estos en boca durante todo el tratamiento. La precisión en la colocación mejora con la técnica de cementado indirecta, ya que permite el acceso a las zonas posteriores, a lugares donde se ve disminuida la visión y además disminuye la condensación de aliento y contaminación salival. Si bien esta técnica requiere tiempo extra de laboratorio, es más rápida en la etapa clínica (AU)

Functional relationship between photosynthetic leaf gas exchange in response to silicon application and water stress mitigation in sugarcane

BACKGROUND: Water stress is one of the serious abiotic stresses that negatively influences the growth, development and production of sugarcane in arid and semi-arid regions. However, silicon (Si) has been applied as an alleviation strategy subjected to environmental stresses. METHODS: In this experiment, Si was applied as soil irrigation in sugarcane plants to understand the mitigation effect of Si against harmful impact of water stress on photosynthetic leaf gas exchange. RESULTS: In the present study we primarily revealed the consequences of low soil moisture content, which affect overall plant performance of sugarcane significantly. Silicon application reduced the adverse effects of water stress by improving the net photosynthetic assimilation rate (Anet) 1.35-18.75%, stomatal conductance to water vapour (gs) 3.26-21.57% and rate of transpiration (E) 1.16-17.83%. The mathematical models developed from the proposed hypothesis explained the functional relationships between photosynthetic responses of Si application and water stress mitigation. CONCLUSIONS: Silicon application showed high ameliorative effects on photosynthetic responses of sugarcane to water stress and could be used for mitigating environmental stresses in other crops, too, in future.