Cartilage-like protein hydrogels engineered via entanglement.

Load-bearing tissues, such as muscle and cartilage, exhibit high elasticity, high toughness and fast recovery, but have different stiffness (with cartilage being significantly stiffer than muscle)1-8. Muscle achieves its toughness through finely controlled forced domain unfolding-refolding in the muscle protein titin, whereas articular cartilage achieves its high stiffness and toughness through an entangled network comprising collagen and proteoglycans. Advancements in protein mechanics and engineering have made it possible to engineer titin-mimetic elastomeric proteins and soft protein biomaterials thereof to mimic the passive elasticity of muscle9-11. However, it is more challenging to engineer highly stiff and tough protein biomaterials to mimic stiff tissues such as cartilage, or develop stiff synthetic matrices for cartilage stem and progenitor cell differentiation12. Here we report the use of chain entanglements to significantly stiffen protein-based hydrogels without compromising their toughness. By introducing chain entanglements13 into the hydrogel network made of folded elastomeric proteins, we are able to engineer highly stiff and tough protein hydrogels, which seamlessly combine mutually incompatible mechanical properties, including high stiffness, high toughness, fast recovery and ultrahigh compressive strength, effectively converting soft protein biomaterials into stiff and tough materials exhibiting mechanical properties close to those of cartilage. Our study provides a general route towards engineering protein-based, stiff and tough biomaterials, which will find applications in biomedical engineering, such as osteochondral defect repair, and material sciences and engineering.

Application of Indian ink markers for locating gastric varices under endoscopic ultrasonography.

OBJECTIVE: The present study aimed to investigate the accuracy of endoscopic ultrasonography (EUS) combined with Indian ink in locating target vessels of gastric varices (GVs) compared with conventional endoscopic techniques. Additionally, the characteristics of GVs under conventional endoscopy were also explored. METHODS: All 50 cirrhotic patients with GVs between August 2021 and December 2022 were included in the study. Firstly, conventional endoscopy was employed to identify GVs and to record the expected injection sites. Subsequently, EUS was used to locate the perforated vessel and the injection site was them marked with India ink followed by injection with cyanoacrylate (CYA). Finally, conventional endoscopy was used to examine GVs, to identify the marker points of Indian ink and to compare whether the injection points under conventional endoscopy were consistent with those marked with Indian ink. Furthermore, patients with consistent and inconsistent distribution of endoscopic markers and injection sites were divided into two groups. RESULTS: EUS could detect the perforating vessels in real time and intuitively. The distribution of markers using EUS was significantly different compared with the injection points obtained by conventional endoscopy (P < 0.001). Therefore, 20 cases were allocated to the consistent group and 30 cases to the non-consistent group. 16 patients who showed red wale signs were obtained in the consistent group and 11 patients in the non-consistent group (P = 0.048). The diameter of the largest GVs was 13.5 (10-15) mm in the consistent group compared with 10 (7.5-10) mm in the non-consistent group (P = 0.006). CONCLUSION: EUS could provide the exact location of GVs, thus more accurately describing the endoscopic characteristics of the GVs. Furthermore, the red wale signs and diameter of the largest GVs obtained using conventional endoscopy were helpful in determining the location of target GVs.

Endoscopic ultrasonography-guided injection of cyanoacrylate in the treatment of gastroesophageal varices type 1: a single-center randomized study.

BACKGROUND AND AIM: First, it has been demonstrated that endoscopic ultrasonography (EUS)-guided cyanoacrylate (CYA) injection (EUS-CYA) has greater efficacy than direct endoscopic injection of cyanoacrylate (DEI-CYA) for treating type 1-isolated gastric varices. However, it is necessary to conduct further studies to determine whether EUS has any advantage over the current guidelines for treating gastroesophageal varices type 1 (GOV1). Second, liver function is an important prognostic factor in patients with liver cirrhosis. Therefore, we evaluated the liver function of patients treated with EUS-CYA. METHODS: In a single-center study, a prospective cohort from February 2021 to September 2022 involving 89 patients with cirrhosis with GOV1 were assigned to undergo EUS-CYA (n = 45) or DEI-CYA (n = 44). The success rate of CYA injection, the rate of overall rebleeding, the rate of reintervention, the complications during the follow-up period, and the liver function were compared. RESULTS: In both groups, 100% of the operations were successful. The follow-up time of the two groups was 290 (153-398) days and 267 (177-416) days, respectively. In the EUS group, the perforating veins had an average diameter of 7.0 ± 2.7 mm, and they had a 100% occlusion rate. A statistically significant difference was found between the two groups regarding the number of sessions needed to eradicate GV (p = 0.005, pairwise comparisons were conducted using the Bonferroni correction method.), the late rebleeding rate after EUS-CYA [n = 3 (6.7%) vs n = 10 (22.7%); p = 0.032], and the incidence of postinjection ulcers [n = 4 (8.9%) vs n = 12 (27.3); p = 0.023)]. Following EUS or DEI-CYA treatment, the patient's liver function did not show any significant deterioration or decline. CONCLUSION: EUS-CYA has a higher eradication success rate and fewer complications, recurrences, and rebleeding episodes than DEI-CYA used for GOV1 treatment. In addition, EUS-CYA did not impair liver function.

Novel balloon compression-assisted endoscopic injection sclerotherapy and endoscopic variceal ligation in the treatment of esophageal varices: a prospective randomized study.

BACKGROUND: Herein, our group designed a novel technology, termed balloon compression-assisted endoscopic injection sclerotherapy (bc-EIS), which was applied to improve the efficiency of eradicating esophageal varices (EVs). The present study aimed to compare the rate of eradication and efficacy between bc-EIS and endoscopic variceal ligation (EVL) in the management of EVs. METHODS: Ninety-five patients with esophageal variceal bleeding (EVB) were randomly assigned to receive bc-EIS or ligation alone. Additional treatment sessions were held 1 month later and then at 3-month intervals until eradication of the varices was achieved. Endoscopic follow-up examinations were carried out at 6-month intervals in the absence of recurrence or immediately if there was any recurrent bleeding. RESULTS: The mean physical injection points per session were 2.89 ± 0.79, and the mean volume of lauromacrogol used per session was 17.74 ± 7.09 ml in the bc-EIS group. The mean band per session was 6.13 ± 0.86. The rate of eradication after one to three rounds of bc-EIS was obviously higher than that of the EVL group (89.36%, 97.87%, and 100% vs. 37.5%, 43.75%, and 47.92%, respectively). Retrosternal pain or discomfort in the bc-EIS group was slightly lower than that in the EVL group (23.4%, 11/47 vs. 31.25%, 15/48). Two and five patients showed mild abdominal bloating and distension between the bc-EIS and EVL groups, respectively (2/47, 4.26% vs. 5/48, 10.42% P > 0.05). Nausea and vomiting were reported in one patient (1/47, 2.13%) in the bc-EIS group and three patients (3/48, 6.25%) in the EVL group. However, there were no statistically significant differences between the two groups (P > 0.05). No fatal or severe complications, such as esophageal perforation, esophageal stricture or ectopic embolism, were observed. CONCLUSION: The bc-EIS method was effective in eradicating EVs and was accompanied by fewer complications.

Comparison of the effects of rapid maxillary expansion versus Twin Block appliance on mandibular growth in skeletal Class II patients.

BACKGROUND: This is a retrospective study that compares mandibular growth changes in skeletal Class II patients treated by rapid maxillary expansion (RME) and following fixed appliance with those patients treated by Twin-Block (TB) and following fixed appliance. METHODS: Fourteen patients treated by RME and following fixed appliance were included into the RME group. Fifteen patients treated by Twin-Block and following fixed appliance were included into the TB group. Lateral cephalometric radiographs taken before treatment and immediately after fixed appliance treatment were used to evaluate mandibular growth effects. RESULTS: The starting forms of the patients in the two groups were examined to be of good comparability. The mandibular length increased significantly in both groups as measured by Co-Gn, Go-Gn and Ar-Gn, but the TB group didn't show more mandibular growth than the RME group (P > 0.05). Skeletal changes of the mandible in vertical dimension were different in the two groups. The change in FMA was 0.35° in the RME group, while the change was 2.65° in the TB group (P < 0.001). The change in LAFH was 5.14 mm in the RME group, significantly smaller than the change of 10.19 mm in the TB group (P < 0.001). CONCLUSION: The investigated Phase I treatment with RME followed by Phase II treatment of fixed appliance achieved the same increases in sagittal mandibular growth and facial profile improvements as the Twin-Block therapy. The treatment with RME followed by fixed appliance was better for vertical control, while the treatment with Twin-Block followed by fixed appliance significantly increased the mandibular plane angle.

The establishment of clonally derived chicken embryonic fibroblast cell line (CSC) with high transfection efficiency and ability as a feeder cell.

This study established a single cloned chicken embryonic fibroblast (CEF) cell line. It solves the main problem of the instability of a cultured primary cell and its impact on the experiment. In this study, CEF pass through this crisis and formed a continuous cell line after subculture. We isolated single postcrisis CEF by a mouth pipette under a convert microscope then established a single cloned cell line named CSC-1-5 which passaged continuously from 96-well plates to 60 mm culture plates. CSC has a normal chicken diploid karyotype, no tumorigenicity, and a high G2/M phase cell ratio. We found that Fugene could mediate the transfection of CSCs efficiently; it was significantly improved compared with the primary cells. It could also promote the proliferation of chicken embryonic stem cell as a feeder layer.

Effect of End-Grafted Polymer Conformation on Protein Resistance.

Monte Carlo simulation combined with an experimental method was used to investigate the effect of the conformational structure of polymer brushes on their protein resistance. The end-grafted polymers with two conformational structures, i.e., linear and looped, were considered. Protein adsorption behaviors on the surfaces grafted with either linear or looped polymers were investigated. Different chain lengths and grafting numbers of end-grafted polymers were employed in this simulation. The simulation results indicated that for long polymer brushes the conformational change from linear to looped generally improved their protein-resistant property for all of the grafting numbers investigated here, and a remarkable improvement in protein resistance can be achieved at a certain grafting number. Moreover, the simulations revealed that the smoothness of the surface and the formation of a dense impenetrable layer are the two significant characteristics of the looped polymer brush in resisting protein adsorption. Meanwhile, experiment results also showed that for a given chain length and grafting number the protein-resistant property of the looped polymer brush was superior to that of the surface grafted with linear polymers, which is quite consistent with the simulation results. These results further elucidated the difference in the protein-resistant property between the linear and looped polymer brushes, which provided useful information for preparing excellent antifouling materials in future experiments.

Hydrostatic Compress Force Enhances the Viability and Decreases the Apoptosis of Condylar Chondrocytes through Integrin-FAK-ERK/PI3K Pathway.

Reduced mechanical stimuli in many pathological cases, such as hemimastication and limited masticatory movements, can significantly affect the metabolic activity of mandibular condylar chondrocytes and the growth of mandibles. However, the molecular mechanisms for these phenomena remain unclear. In this study, we hypothesized that integrin-focal adhesion kinase (FAK)-ERK (extracellular signal-regulated kinase)/PI3K (phosphatidylinositol-3-kinase) signaling pathway mediated the cellular response of condylar chondrocytes to mechanical loading. Primary condylar chondrocytes were exposed to hydrostatic compressive forces (HCFs) of different magnitudes (0, 50, 100, 150, 200, and 250 kPa) for 2 h. We measured the viability, morphology, and apoptosis of the chondrocytes with different treatments as well as the gene, protein expression, and phosphorylation of mechanosensitivity-related molecules, such as integrin α2, integrin α5, integrin ß1, FAK, ERK, and PI3K. HCFs could significantly increase the viability and surface area of condylar chondrocytes and decrease their apoptosis in a dose-dependent manner. HCF of 250 kPa resulted in a 1.51 ± 0.02-fold increase of cell viability and reduced the ratio of apoptotic cells from 18.10% ± 0.56% to 7.30% ± 1.43%. HCFs could significantly enhance the mRNA and protein expression of integrin α2, integrin α5, and integrin ß1 in a dose-dependent manner, but not ERK1, ERK2, or PI3K. Instead, HCF could significantly increase phosphorylation levels of FAK, ERK1/2, and PI3K in a dose-dependent manner. Cilengitide, the potent integrin inhibitor, could dose-dependently block such effects of HCFs. HCFs enhances the viability and decreases the apoptosis of condylar chondrocytes through the integrin-FAK-ERK/PI3K pathway.

Repeated intraperitoneal injections of liposomes containing phosphatidic acid and cardiolipin reduce amyloid-ß levels in APP/PS1 transgenic mice.

The accumulation of extracellular amyloid-beta (Aß) peptide and intracellular neurofibrillary tangles in the brain are two major neuropathological hallmarks of Alzheimer's disease (AD). It is thought that an equilibrium exists between Aß in the brain and in the peripheral blood and thus, it was hypothesized that shifting this equilibrium towards the blood by enhancing peripheral clearance might reduce Aß levels in the brain: the 'sink effect'. We tested this hypothesis by intraperitoneally injecting APP/PS1 transgenic mice with small unilamellar vesicles containing either phosphatidic acid or cardiolipin over 3weeks. This treatment reduced significantly the amount of Aß in the plasma and the brain levels of Aß were lighter affected. Nevertheless, this dosing regimen did modulate tau phosphorylation and glycogen synthase kinase 3 activities in the brain, suggesting that the targeting of circulating Aß may be therapeutically relevant in AD. FROM THE CLINICAL EDITOR: Intraperitoneal injection of small unilamellar vesicles containing phosphatidic acid or cardiolipin significantly reduced the amount of amyloid-beta (Aß) peptide in the plasma in a rodent model. Brain levels of Aß were also affected - although to a lesser extent - suggesting that targeting of circulating Aß may be therapeutically relevant of Alzheimer's disease.

Influence of the Pd Oxidation State in PdNi Thin Films on Surface Acoustic Wave Hydrogen Sensing Performance.

PdNi alloy thin films demonstrate exceptional hydrogen sensing performance and exhibit significant potential for application in surface acoustic wave (SAW) hydrogen sensors. However, the long-term stability of SAW H2 sensors utilizing PdNi films as catalysts experiences a substantial decrease during operation. In this paper, X-ray photoelectron spectroscopy (XPS) is employed to investigate the failure mechanisms of PdNi thin films under operational conditions. The XPS analysis reveals that the formation of PdO species on PdNi thin films plays a crucial role in the failure of hydrogen sensing. Additionally, density functional theory (DFT) calculations indicate that hydrogen atoms encounter a diffusion energy barrier during the penetration process from the PdNiOx surface to the subsurface region. The identification of PdNi film failure mechanisms through XPS and DFT offers valuable insights into the development of gas sensors with enhanced long-term stability. Guided by these mechanisms, we propose a method to restore the hydrogen sensing response time and magnitude to a certain extent by reducing the partially oxidized surface of the PdNi alloy under a hydrogen atmosphere at 70 °C, thereby restoring Pd to its metallic state with zero valence.

Degradable chitosan-based bioplastic packaging: Design, preparation and applications.

Food packaging is an essential part of food transportation, storage and preservation. Biodegradable biopolymers are a significant direction for the future development of food packaging materials. As a natural biological polysaccharide, chitosan has been widely concerned by researchers in the field of food packaging due to its excellent film-forming property, good antibacterial property and designability. Thus, the application research of chitosan-based food packaging films, coatings and aerogels has been greatly developed. In this review, recent advances on chitosan-based food packaging materials are summarized. Firstly, the development background of chitosan-based packaging materials was described, and then chitosan itself was introduced. In addition, the design, preparation and applications of films, coatings and aerogels in chitosan-based packaging for food preservation were discussed, and the advantages and disadvantages of each research in the development of chitosan-based packaging materials were analyzed. Finally, the application prospects, challenges and suggestions for solving the problems of chitosan-based packaging are summarized and prospected.

Flexible, biodegradable ultrasonic wireless electrotherapy device based on highly self-aligned piezoelectric biofilms.

Biodegradable piezoelectric devices hold great promise in on-demand transient bioelectronics. Existing piezoelectric biomaterials, however, remain obstacles to the development of such devices due to difficulties in large-scale crystal orientation alignment and weak piezoelectricity. Here, we present a strategy for the synthesis of optimally orientated, self-aligned piezoelectric γ-glycine/polyvinyl alcohol (γ-glycine/PVA) films via an ultrasound-assisted process, guided by density functional theory. The first-principles calculations reveal that the negative piezoelectric effect of γ-glycine originates from the stretching and compression of glycine molecules induced by hydrogen bonding interactions. The synthetic γ-glycine/PVA films exhibit a piezoelectricity of 10.4 picocoulombs per newton and an ultrahigh piezoelectric voltage coefficient of 324 × 10-3 volt meters per newton. The biofilms are further developed into flexible, bioresorbable, wireless piezo-ultrasound electrotherapy devices, which are demonstrated to shorten wound healing by ~40% and self-degrade in preclinical wound models. These encouraging results offer reliable approaches for engineering piezoelectric biofilms and developing transient bioelectronics.

Plasma proteins adsorption mechanism on polyethylene-grafted poly(ethylene glycol) surface by quartz crystal microbalance with dissipation.

Protein adsorption has a vital role in biomaterial surface science because it is directly related to the hemocompatibility of blood-contacting materials. In this study, monomethoxy poly(ethylene glycol) (mPEG) with two different molecular weights was grafted on polyethylene as a model to elucidate the adsorption mechanisms of plasma protein through quartz crystal microbalance with dissipation (QCM-D). Combined with data from platelet adhesion, whole blood clotting time, and hemolysis rate, the blood compatibility of PE-g-mPEG film was found to have significantly improved. Two adsorption schemes were developed for real-time monitoring of protein adsorption. Results showed that the preadsorbed bovine serum albumin (BSA) on the surfaces of PE-g-mPEG films could effectively inhibit subsequent adsorption of fibrinogen (Fib). Nonspecific protein adsorption of BSA was determined by surface coverage, not by the chain length of PEG. Dense PEG brush could release more trapped water molecules to resist BSA adsorption. Moreover, the preadsorbed Fib could be gradually displaced by high-concentration BSA. However, the adsorption and displacement of Fib was determined by surface hydrophilicity.

The influence of chronic fluorosis on mitochondrial dynamics morphology and distribution in cortical neurons of the rat brain.

The present study was designed to evaluate the effects of chronic fluorosis on the dynamics (including fusion and fission proteins), fragmentation, and distribution of mitochondria in the cortical neurons of the rat brain in an attempt to elucidate molecular mechanisms underlying the brain damage associated with excess accumulation of fluoride. Sixty Sprague-Dawley rats were divided randomly into three groups of 20 each, that is, the untreated control group (drinking water naturally containing <0.5 mg fluoride/l, NaF), the low-fluoride group (whose drinking water was supplemented with 10 mg fluoride/l) and the high-fluoride group (50 mg fluoride/l). After 6 months of exposure, the expression of mitofusin-1 (Mfn1), fission-1 (Fis1), and dynamin-related protein-1 (Drp1) at both the protein and mRNA levels were detected by Western blotting, immunohistochemistry, and real-time PCR, respectively. Moreover, mitochondrial morphology and distribution in neurons were observed by transmission electron or fluorescence microscopy. In the cortices of the brains of rats with chronic fluorosis, the level of Mfn1 protein was clearly reduced, whereas the levels of Fis1 and Drp1 were elevated. The alternations of expression of the mRNAs encoding all three of these proteins were almost the same as the corresponding changes at the protein levels. The mitochondria were fragmented and the redistributed away from the axons of the cortical neurons. These findings indicate that chronic fluorosis induces abnormal mitochondrial dynamics, which might in turn result in a high level of oxidative stress.

A Novel Strategy for Liposomal Drug Separation in Plasma by TiO2 Microspheres and Application in Pharmacokinetics.

Purpose: Liposomes are nano-scale materials with a biofilm-like structure. They have excellent biocompatibility and are increasingly useful in drug delivery systems. However, the in vivo fate of liposomal drugs is still unclear because existing bioanalytical methods for quantitation of total and liposomal-encapsulated drugs have limits. A novel strategy for liposomal-encapsulated drug separation from plasma was developed via the specific coordinate binding interaction of TiO2 microspheres with the phosphate groups of liposomes. Methods: Liposomal-encapsulated docetaxel was separated from plasma by TiO2 microspheres and analyzed by the UPLC-MS/MS method. The amount of TiO2, pH of the dilutions, plasma dilution factors and incubation time were optimized to improve extraction recovery. The characterization of the adsorption of liposome-encapsulated drugs by TiO2 microspheres was observed by electron microscopy. For understanding the mechanism, pseudo-first and the pseudo-second order equations were proposed for the adsorption process. The study fully validated the method for quantitation of liposomal-encapsulated in plasma and the method was applied to the pharmacokinetic study of docetaxel liposomes. Results: The encapsulated docetaxel had a concentration range of 15-4000 ng/mL from the plasma sample using a TiO2 extraction method. Successful method validation proved the method was sensitive, selective and stable, and was suitable for quantitation of docetaxel liposomes in plasma samples. Extraction recovery of this method was higher than that of SPE method. As shown in electron microscopy, the liposomes adsorbed on TiO2 microspheres were intact and there was no drug leakage. The study proposed pseudo-first and the pseudo-second order equations to facilitate the adsorption of liposomal drugs with TiO2 microspheres. The proposed strategy supports the pharmacokinetic study of docetaxel liposomes in rats. Conclusion: TiO2 extraction method was stable, reproducible, and reliable for quantitation of encapsulated docetaxel. Because of versatility of lipids, it is expected to a universal bioanalysis method for the pharmacokinetic study of liposomes.

Microarray with micro- and nano-topographies enables identification of the optimal topography for directing the differentiation of primary murine neural progenitor cells.

During development and tissue repair, progenitor cells are guided by both biochemical and biophysical cues of their microenvironment, including topographical signals. The topographical cues have been shown to play an important role in controlling the fate of cells. Systematic investigation of topographical structures with different geometries and sizes under the identical experimental conditions on the same chip will enhance the understanding of the role of shape and size in cell-topography interactions. A simple customizable multi-architecture chip (MARC) array is therefore developed to incorporate, on a single chip, distinct topographies of various architectural complexities, including both isotropic and anisotropic features, in nano- to micrometer dimensions, with different aspect ratios and hierarchical structures. Polydimethylsiloxane (PDMS) replicas of MARC are used to investigate the influence of different geometries and sizes in neural differentiation of primary murine neural progenitor cells (mNPCs). Anisotropic gratings (2 µm gratings, 250 nm gratings) and isotropic 1 µm pillars significantly promote differentiation of mNPCs into neurons, as indicated by expression of ß-III-tubulin (59%, 58%, and 58%, respectively, compared to 30% on the control). In contrast, glial differentiation is enhanced on isotropic 2 µm holes and 1 µm pillars. These results illustrate that anisotropic topographies enhance neuronal differentiation while isotropic topographies enhance glial differentiation on the same chip under the same conditions. MARC enables simultaneous cost-effective investigation of multiple topographies, allowing efficient optimization of topographical and biochemical cues to modulate cell differentiation.

In vivo visualisation of nanoparticle entry into central nervous system tissue.

Because the potential neurotoxicity of nanoparticles is a significant issue, characterisation of nanoparticle entry into the brain is essential. Here, we describe an in vivo confocal neuroimaging method (ICON) of visualising the entry of fluorescent particles into the parenchyma of the central nervous system (CNS) in live animals using the retina as a model. Rats received intravenous injections of fluorescence-labelled polybutyl cyanoacrylate nanoparticles that had been synthesised by a standard miniemulsion polymerisation process. We performed live recording with ICON from before and up to 9 days after particle injection and took photomicrographs of the retina. In addition, selective retrograde labelling of the retinal ganglion cells was achieved by stereotaxic injection of a fluorescent dye into the superior colliculus. Using ICON, we observed vascular kinetics of nanoparticles (wash-in within seconds), their passage to the retina parenchyma (within minutes) and their distribution (mainly cellular) under in vivo conditions. For the detection of cell loss--which is important for the evaluation of toxic effects--in another experiment, we semi-quantitatively analysed the selectively labelled retinal neurons. Our results suggest that the dye per se does not lead to neuronal death. With ICON, it is possible to study nanoparticle kinetics in the retina as a model of the blood-brain barrier. Imaging data can be acquired within seconds after the injection, and the long-term fate of cellular uptake can be followed for many days to study the cellular/extracellular distribution of the nanoparticles. ICON is thus an effective and meaningful tool to investigate nanoparticle/CNS interactions.

Effect of electric current intensity on performance of polycaprolactone/FeS2-based mixotrophic biofilm-electrode reactor.

In this study, a bioelectrochemical system consisting of pyrite-based autotrophic denitrification (PAD) and heterotrophic denitrification (HD) was established to polish nitrate wastewater. The loading of electric current (EC) could stimulate the dissolution of pyrite. Appropriate EC (I ≤ 30 mA) was conducive to nitrate removal, too high EC (I = 40 mA) would inhibit nitrate removal and lead to an obvious accumulation of NO2--N and NH4+-N. Microbial analysis revealed that the increase of EC could inhibit the diversity of heterotrophic microbes, but appropriate EC (I = 10 mA) could increase the diversity of autotrophic microbes. The EC loading was conducive to the enrichment of iron autotrophic denitrifiers (Ferritrophicum), pyrite-oxidizing bacteria (Thiobacillus, Sulfurimonas), and sulfur autotrophic denitrifiers (Dechloromonas, Thiobacillus, and Arenimonas). The EC loading enlarged the contribution of PAD, making PAD a dominant pathway in denitrification.

Effects of SNPs in SOD2 and SOD3 interacted with fluoride exposure on the susceptibility of dental fluorosis.

A total of 649 children aged 7-13 years of age were recruited in a cross-sectional study in Tongxu County, China (2017) to assess the effects of interaction between single nucleotide polymorphisms (SNPs) in SOD2 and SOD3 gene and fluoride exposure on dental fluorosis (DF) status. Associations between biomarkers and DF status were evaluated. Logistic regression suggested that the risk of DF in children with rs10370 GG genotype and rs5746136 TT genotype was 1.89-fold and 1.72-fold than that in children with TT/CC genotype, respectively. Increased T-SOD activity was associated with a lower risk of DF (OR = 0.99). The rs2855262*rs10370*UF model was regarded as the optimal interaction model in generalized multifactor dimensionality reduction analyses. Our findings suggested that rs4880 and rs10370 might be useful genetic markers for DF, and there might be interactions among rs10370 in SOD2, rs2855262 in SOD3, and fluoride exposure on DF status.

Directional spread of surface-associated retroviruses regulated by differential virus-cell interactions.

The spread of viral infections involves the directional progression of virus particles from infected cells to uninfected target cells. Prior to entry, the binding of virus particles to specific cell surface receptors can trigger virus surfing, an actin-dependent lateral transport of viruses toward the cell body (M. J. Lehmann et al., J. Cell Biol. 170:317-325, 2005; M. Schelhaas, et al., PLoS Pathog. 4:e1000148, 2008; J. L. Smith, D. S. Lidke, and M. A. Ozbun, Virology 381:16-21, 2008). Here, we have used live-cell imaging to demonstrate that for cells chronically infected with the gammaretrovirus murine leukemia virus in which receptor has been downregulated, a significant portion of completely assembled virus particles are not immediately released into the supernatant but retain long-term association with the cell surface. Retention can be attributed, at least in part, to nonspecific particle attachment to cell surface glycosylaminoglycans. In contrast to virus surfing, viruses retained at the surface of infected cells undergo a lateral motility that is random and actin independent. This diffusive motility can be abruptly halted and converted into inward surfing after treatment with Polybrene, a soluble cation that increases virus-cell adsorption. In the absence of Polybrene, particle diffusion allows for an outward flow of viruses to the infected cell periphery. Peripheral particles are readily captured by and transmitted to neighboring uninfected target cells in a directional fashion. These data demonstrate a surface-based mechanism for the directional spread of viruses regulated by differential virus-cell interactions.