Functional and structural analyses reveal that a dual domain sialidase protects bacteria from complement killing through desialylation of complement factors.

The complement system is the first line of innate immune defense against microbial infections. To survive in humans and cause infections, bacterial pathogens have developed sophisticated mechanisms to subvert the complement-mediated bactericidal activity. There are reports that sialidases, also known as neuraminidases, are implicated in bacterial complement resistance; however, its underlying molecular mechanism remains elusive. Several complement proteins (e.g., C1q, C4, and C5) and regulators (e.g., factor H and C4bp) are modified by various sialoglycans (glycans with terminal sialic acids), which are essential for their functions. This report provides both functional and structural evidence that bacterial sialidases can disarm the complement system via desialylating key complement proteins and regulators. The oral bacterium Porphyromonas gingivalis, a "keystone" pathogen of periodontitis, produces a dual domain sialidase (PG0352). Biochemical analyses reveal that PG0352 can desialylate human serum and complement factors and thus protect bacteria from serum killing. Structural analyses show that PG0352 contains a N-terminal carbohydrate-binding module (CBM) and a C-terminal sialidase domain that exhibits a canonical six-bladed ß-propeller sialidase fold with each blade composed of 3-4 antiparallel ß-strands. Follow-up functional studies show that PG0352 forms monomers and is active in a broad range of pH. While PG0352 can remove both N-acetylneuraminic acid (Neu5Ac) and N-glycolyl-neuraminic acid (Neu5Gc), it has a higher affinity to Neu5Ac, the most abundant sialic acid in humans. Structural and functional analyses further demonstrate that the CBM binds to carbohydrates and serum glycoproteins. The results shown in this report provide new insights into understanding the role of sialidases in bacterial virulence and open a new avenue to investigate the molecular mechanisms of bacterial complement resistance.

Human blood metabolites and risk of sepsis: A Mendelian randomization investigation.

BACKGROUND: Evidence supports the observational correlations between human blood metabolites and sepsis. However, whether these associations represent a causal relationship is unknown. In this study, we applied two-sample Mendelian randomization (MR) analyses to examine causality between genetically proxied 486 blood metabolites and sepsis risk. METHODS: We used summary data from genome-wide association studies (GWAS) on 486 metabolites involving 7824 individuals as exposure and a sepsis GWAS including 11,643 cases and 474,841 controls as the outcome. The inverse-variance weighted (IVW) was the primary method to estimate the causal relationship between exposure and outcome, with MR-Egger and weighted median serving as supplements. Sensitivity analyses were implemented with Cochrane's Q test, MR-Egger intercept, MR-PRESSO and leave-one-out analysis. In addition, we performed replication MR, meta-analysis, Steiger test, linkage disequilibrium score (LDSC) regression and multivariable MR (MVMR) to thoroughly verify the causation. RESULTS: We identified that genetically determined high levels of 1-oleoylglycerophosphoethanolamine (odds ratio (OR) = .52, 95% confidence interval (CI): .31-.87, p = .0122), alpha-glutamyltyrosine (OR = .75, 95% CI: .60-.93, p = .0102), heptanoate (7:0) (OR = .51, 95% CI: .33-.81, p = .0041) and saccharin (OR = .84, 95% CI: .74-.94, p = .0036) were causally associated with a lower risk of sepsis. MVMR analysis demonstrated the independent causal effect of these metabolites on sepsis. CONCLUSIONS: These findings indicated that four blood metabolites have a protective impact on sepsis, thus providing novel perspectives into the metabolite-mediated development mechanism of sepsis by combining genomics and metabolomics.

Association of gut microbiota with COVID-19 susceptibility and severity: A two-sample Mendelian randomization study.

Evidence supports the observational associations of gut microbiota with the risk of COVID-19; however, it is unclear whether these associations reflect a causal relationship. This study investigated the association of gut microbiota with COVID-19 susceptibility and severity. Data were obtained from a large-scale gut microbiota data set (n = 18 340) and the COVID-19 Host Genetics Initiative (n = 2 942 817). Causal effects were estimated with inverse variance weighted (IVW), MR-Egger, and weighted median, and sensitivity analyses were implemented with Cochran's Q test, MR-Egger intercept test, MR-PRESSO, leave-one-out analysis, and funnel plots. For COVID-19 susceptibility, IVW estimates suggested that Gammaproteobacteria (odds ratio [OR] = 0.94, 95% confidence interval [CI], 0.89-0.99, p = 0.0295] and Streptococcaceae (OR = 0.95, 95% CI, 0.92-1.00, p = 0.0287) had a reduced risk, while Negativicutes (OR = 1.05, 95% CI, 1.01-1.10, p = 0.0302), Selenomonadales (OR = 1.05, 95% CI, 1.01-1.10, p = 0.0302), Bacteroides (OR = 1.06, 95% CI, 1.01-1.12, p = 0.0283), and Bacteroidaceae (OR = 1.06, 95% CI, 1.01-1.12, p = 0.0283) were associated with an increased risk (all p < 0.05, nominally significant). For COVID-19 severity, Subdoligranulum (OR = 0.80, 95% CI, 0.69-0.92, p = 0.0018), Cyanobacteria (OR = 0.85, 95% CI, 0.76-0.96, p = 0.0062), Lactobacillales (OR = 0.87, 95% CI, 0.76-0.98, p = 0.0260), Christensenellaceae (OR = 0.87, 95% CI, 0.77-0.99, p = 0.0384), Tyzzerella3 (OR = 0.89, 95% CI, 0.81-0.97, p = 0.0070), and RuminococcaceaeUCG011 (OR = 0.91, 95% CI, 0.83-0.99, p = 0.0247) exhibited negative correlations, while RikenellaceaeRC9 (OR = 1.09, 95% CI, 1.01-1.17, p = 0.0277), LachnospiraceaeUCG008 (OR = 1.12, 95% CI, 1.00-1.26, p = 0.0432), and MollicutesRF9 (OR = 1.14, 95% CI, 1.01-1.29, p = 0.0354) exhibited positive correlations (all p < 0.05, nominally significant). Sensitivity analyses validated the robustness of the above associations. These findings suggest that gut microbiota might influence the susceptibility and severity of COVID-19 in a causal way, thus providing novel insights into the gut microbiota-mediated development mechanism of COVID-19.

Triboelectric Nanogenerators Assembled by Cobalt(II) Coordination Polymer Incorporated Composite Films and their Application for Self-Powered Anticorrosion.

A friction layer with stability and durability is important to promote the practical application of triboelectric nanogenerators (TENGs). In this work, a two-dimensional cobalt coordination polymer (Co-CP) was successfully synthesized using cobalt nitrate, 4,4',4''-tricarboxyltriphenylamine and 2,2'-bipyridine. To clearly clarify the effect of the doping proportions of Co-CP and the types of composite polymers on the output performance of the TENG, Co-CP was combined with two organic polymers having different polarities (polyvinylidene fluoride (PVDF) and ethyl cellulose (EC)) to form a series of composite films, which were used as the friction electrode materials to fabricate TENGs. Electrical characterizations indicated that a high output current and voltage were obtained from the TENG based on 15 wt.% Co-CP incorporated in PVDF (Co-CP@PVDF), which could be further improved by the Co-CP@EC composite film at the same doping ratio. Furthermore, the optimally fabricated TENG was demonstrated to prevent electrochemical corrosion of carbon steel.

Impact of occlusal reconstruction positions on airway dimensions in patients with edentulism and long centric occlusion.

OBJECTIVE: To study the airway changes of edentulous patients with a magnitude of long centric (MLC) ≥ 1.5 mm during occlusal reconstruction at the centric relation position (CRP) and muscular position (MP). METHODS: The CRP and MP were determined by Gothic arch. The cephalometric analysis was taken at the two occlusal positions. The sagittal distance of each part of the upper airway was measured. The differences between two occlusal positions were compared. The difference values were calculated by subtracting the two. The correlation between the MLC and the difference value was analyzed. RESULTS: The sagittal diameters of palatopharynx and glossopharynx airway at MP were statistically larger than those at CRP (P < 0.05). The MLC had a strong correlation with the ANB angle (r = 0.745, P < 0.001). CONCLUSION: Compared with the occlusal position of CRP, occlusion reconstruction at MP can provide better airway condition for edentulous patients with large MLC.

Efficacy and safety of mitoxantrone hydrochloride liposome injection in Chinese patients with advanced breast cancer: a randomized, open-label, active-controlled, single-center, phase II clinical trial.

PURPOSE: This trial aimed to evaluate the efficacy and safety of mitoxantrone hydrochloride liposome injection (Lipo-MIT) in advanced breast cancer (ABC). METHODS: In this randomized, open-label, active-controlled, single-center, phase II clinical trial, eligible patients were randomized in a ratio of 1:1 to receive Lipo-MIT or mitoxantrone hydrochloride injection (MIT) intravenously. The primary endpoint was objective response rate (ORR). The secondary endpoints were disease control rate (DCR), progression-free survival (PFS), and safety outcomes. RESULTS: Sixty patients were randomized to receive Lipo-MIT or MIT. The ORR was 13.3% (95% confidence interval (CI): 3.8-30.7%) for Lipo-MIT and 6.7% (95% CI: 0.8-22.1%) for MIT. The DCR was 50% (95% CI: 31.3-68.7%) with Lipo-MIT vs. 30% (95% CI: 14.7-49.4%) with MIT. The median PFS was 1.92 months (95% CI: 1.75-3.61) for Lipo-MIT and 1.85 months (95% CI: 1.75-2.02) for MIT. The most common toxicity was myelosuppression. Lipo-MIT resulted in an incidence of 86.7% of leukopenia and 80.0% of neutropenia, which was marginally superior to MIT (96.7% and 96.7%, respectively). Lipo-MIT showed a lower incidence of cardiovascular events (13.3% vs. 20.0%) and increased cardiac troponin T (3.3% vs. 36.7%); but higher incidence of anemia (76.7% vs. 46.7%), skin hyperpigmentation (66.7% vs. 3.3%), and fever (23.3% vs. 10.0%) than MIT. Conclusions The clinical benefit parameters of Lipo-MIT and MIT were comparable. Lipo-MIT provided a different toxicity profile, which might be associated with the altered distribution of the drug. Additional study is needed to elucidate the potential benefit of Lipo-MIT in ABC. CLINICAL TRIAL REGISTRATION: This study is registered with ClinicalTrials.gov (No. NCT02596373) on Nov 4, 2015.

mTORC1 promotes mineralization via p53 pathway.

The objectives of our study were to investigate the roles of mTORC1 in odontoblast proliferation and mineralization and to determine the mechanism by which mTORC1 regulates odontoblast mineralization. In vitro, MDPC23 cells were treated with rapamycin (10 nmol/L) and transfected with a lentivirus for short hairpin (shRNA)-mediated silencing of the tuberous sclerosis complex (shTSC1) to inhibit and activate mTORC1, respectively. CCK8 assays, flow cytometry, Alizarin red S staining, ALP staining, qRT-PCR, and western blot analysis were performed. TSC1-conditional knockout (DMP1-Cre+ ; TSC1f/f , hereafter CKO) mice and littermate control (DMP1-Cre- ; TSC1f/f , hereafter WT) mice were generated. H&E staining, immunofluorescence, and micro-CT analysis were performed. Transcriptome sequencing analysis was used to screen the mechanism of this process. mTORC1 inactivation decreased the cell proliferation. The qRT-PCR and western blot results showed that mineralization-related genes and proteins were downregulated in mTORC1-inactivated cells. Moreover, mTORC1 overactivation promoted cell proliferation and mineralization-related gene and protein expression. In vivo, the micro-CT results showed that DV/TV and dentin thickness were higher in CKO mice than in controls and H&E staining showed the same results. Mineralization-related proteins expression was upregulated. Transcriptome sequencing analysis revealed that p53 pathway-associated genes were differentially expressed in TSC1-deficient cells. By inhibiting p53 alone or both mTORC1 and p53 with rapamycin and a p53 inhibitor, we elucidated that p53 acts downstream of mTORC1 and that mTORC1 thereby promotes odontoblast mineralization. Taken together, our findings demonstrate that the role of mTORC1 in odontoblast proliferation and mineralization, and confirm that mTORC1 upregulates odontoblast mineralization via the p53 pathway.

Comparison of the Effects of 3D Printing Bioactive Porous Titanium Alloy Scaffolds and Nano-biology for Direct Treatment of Bone Defects.

This study was to compare the effects of three-dimensional (3D) printed bioactive porous titanium alloy scaffolds (3DP-BPTAS) and rhBMP-2/PLA-loaded sustained-release nanospheres (SRNs) in the treatment of bone defects. In this study, the bioactive porous titanium alloy scaffolds (BPTAS) with different pore sizes were prepared by selective laser melting (SLM) technology. The rhBMP-2/PLA SRNs were prepared by the double emulsion solvent volatilization method. The morphology of the two nanomaterials was observed under a scanning electron microscope (SEM). The encapsulation rate (ER), drug loading (DL), and in vitro release rate of the SRNs were detected by enzyme-linked immunosorbent assay (ELISA); and the effects of different particle sizes of BPTAS and SRNs on the proliferation of BMSCs were measured using the Methyl Thiazolyl Tetrazolium (MTT) method. 42 healthy male rabbits were selected and rolled into a control group (no treatment), a model group (the femoral condyle defect model), an A800 group (model + 800 µm of BPTAS), and an A1000 group (model + 1000 µm of BPTAS), an A1200 group (model + 1200 µm of BPTAS), an A1500 group (model + 1500 µm of BPTAS), and an SNR group (model + rhBMP-2/PLA SRNs). There were 6 rabbits in each group, and they were sacrificed 4, 8, and 12 weeks after the surgery. They were performed with general observation, X-ray photography, and histological and biomechanical examinations. According to the Lane-Sandhu bone defect repair tissue X-ray and histological scoring standard, the effect of bone defect repair was evaluated. It was found that the actual pore structure of the scaffold prepared by the SLM process was consistent with the theoretical design. The observation under TEM showed that rhBMP-2/PLA SRNs were approximately round, with an average particle size of 835 nm, and its encapsulation efficiency and drug loading rate were 89.02 ± 5.14% and 0.033 ± 0.004%, respectively. The rhBMP-2/PLA SRNs and BPTAS had no statistically obvious increase in the number of cells after cell treatment compared with the control group (P> 0.05). At 12 weeks postoperatively, the stent bone tissue growing distance (SBTGD) in the SRN group was longer than that in the A1000 group (P< 0.01), and that in the A1000 group was better in contrast to the A800, A1200, and A1500 groups (P< 0.01). The Lane-Sandhu X-ray score of the SRN group was better than other groups (P< 0.05). It suggested that 3DP-BPTAS and rhBMP-2/PLA SRNs could repair the bone defects, and rhBMP-2/PLA SRNs were more conducive to the formation of new bone tissue.

Recent Advances of Porous Materials Based on Cyclodextrin.

Porous materials have attracted significant attention because of their rising applications in many fields. Cyclodextrins (CDs) are suitable building units in the fabrication of porous materials owing to their intrinsic nanoporous structure, easy modification, and biocompatibility, which may result in the formation of CD-based organic frameworks (including cyclodextrin metal-organic frameworks (CD-MOFs) and cyclodextrin covalent organic frameworks (CD-COFs)), and CD-based polymer hybrid porous materials. This review focuses on the recent progress in the fabrication and applications of CD-based porous materials with novel structures and functionalities.

Effect of gal/GalNAc regioisomerism in galactosylated liposomes on asialoglycoprotein receptor-mediated hepatocyte-selective targeting in vivo.

In this study, we describe a novel synthesis of galactosylated lipids by lipase catalysis. Lactitol (Lac), galactose (Gal), or N-acetyl galactosamine (GalNAc) was coupled with cholesterol (CHS) as target head groups by enzyme-catalyzed regioselective esterification to produce three kinds of lipids: CHS-1-Gal, CHS-6-Gal, or CHS-6-GalNAc1. The biological effects of galactosylated lipids carrying different constitutional isomers of the pendent sugar species were investigated. LP-1-Gal (liposomes containing 5.0 molar% of CHS-1-Gal) showed strong binding to tetrameric lectins of Ricinus communis agglutinin (RCA120) in vitro, while LP-6-Gal (liposomes containing 5.0 molar% of CHS-6-Gal) and LP-6-GalNAc (liposomes containing 5.0 molar% of CHS-6-GalNAc) did not. After intravenous injection, LP-6-GalNAc, LP-1-Gal and LP-6-Gal rapidly disappeared from the blood and accumulated rapidly in liver (up to 74.88 ± 4.11%, 58.67 ± 5.75%, and 47.66 ± 4.56% of injected dose/g organ within 4 h, respectively). This is significantly higher than the uptake of unmodified liposomes (Unmod-LP) (18.67 ± 6.07%). Pre-injection of asialofetuin significantly inhibits liver uptake of Gal-liposomes (P < 0.01), with the degree of inhibition appearing in the following order: LP-6-GalNAc (73.29%) > LP-1-Gal (67.06%) > LP-6-Gal (53.61%). More importantly, LP-6-GalNAc was preferentially taken up by hepatocytes and the uptake ratio by parenchymal cells (PC) and nonparenchymal cells (NPC) (PC/NPC ratio) was 11.03 higher than LP-1-Gal (7.32), LP-6-Gal (5.83) and Unmod-LP (2.39). We suggest that liposomes containing the novel galactosylated lipid CHS-6-GalNAc have potential as drug delivery carriers for hepatocyte-selective targeting.

Distribution and source of microplastics in China's second largest reservoir - Danjiangkou Reservoir.

Fresh water microplastic pollution is of pressing concern globally, but its distribution and sources in reservoirs are poorly documented. Danjiangkou Reservoir is the second largest reservoir in China and is divided into the Han Reservoir and Dan Reservoir. In this work, microplastic abundances and morphological characteristics of the reservoir were investigated. The microplastic abundance of 15 main tributaries of the reservoir was also measured. The vertical distribution (in water column and sediment), horizontal distribution (in Han Reservoir and Dan Reservoir) and source of microplastics were analyzed. Microplastics accumulated in the middle layer of the reservoir, and the size and color of the microplastic particles changed from the surface to the bottom, which implies that surveys of surface water are not enough to determine the microplastic contamination for deep water reservoirs. In the surface water, the microplastic abundance in the Han Reservoir was lower than that in the Dan Reservoir (p < 0.05), but microplastic abundance did not differ significantly in the intermediate and bottom water. Tributaries were one of the main sources of microplastics for Han Reservoir but not for Dan Reservoir. Agricultural cultivation in the hydro-fluctuation belt might be an important source of microplastics in the Dan Reservoir, which should be given additional attention. The results of this study can provide valuable information for developing microplastic sampling strategies in deep water reservoirs. Further studies are recommended to investigate the process through which microplastics in the hydro-fluctuation belt enter the reservoir and the sinking behavior of microplastics in the reservoir.

Nonvascularized Iliac Bone Reconstruction for the Mandible Without Maxillofacial Skin Scarring.

PURPOSE: There are many methods to reconstruct the mandible, but they are often accompanied by trauma, which can lead to scarring of the maxillofacial skin. The purpose of this study was to show the utility of a minimally invasive method for reconstruction of the mandible with nonvascularized iliac bone grafts without a skin scar, as well as to evaluate the success rate and complications. PATIENTS AND METHODS: This was a retrospective case series. We retrospectively analyzed patients who underwent transoral resection of benign mandibular pathologies, followed by nonvascularized iliac bone graft reconstruction. The primary outcome variable was the success rate of the bone grafts. Secondary outcome variables were postoperative complications at the grafted bone recipient and donor sites, the long-term absorptivity of grafted bone, and the type of mandibular defect. We computed descriptive statistics or performed the χ2 test for each variable. RESULTS: Overall, 54 patients were included in the study, including 21 male and 33 female patients, with an age range of 10 to 65 years. The complete survival rate was 87.0% (47 of 54 patients), and the partial survival rate was 98.1% (53 of 54). The average bone absorption rate 3 years after surgery was 1.8 to 30.7%. We propose a new classification method for mandibular defects based on the extent of the tumor, location of the osteotomy, and degree of surgical difficulty. CONCLUSIONS: Intraoral nonvascularized iliac bone grafting is a highly successful minimally invasive method for mandibular reconstruction. It is also one of the best methods for mandibular reconstruction in patients with benign mandibular tumors without soft tissue involvement.

A Novel Method for Reconstruction of the Lower Lip After Lip Cancer Ablation: Double Abbe Flap.

PURPOSE: Repair of large defects caused by lip cancer resection is often a challenge for surgeons. The aim of this study was to explore the treatment and outcomes of lower lip reconstruction with a novel surgical procedure after lip cancer ablation. PATIENTS AND METHODS: We performed a retrospective case-series study involving patients who underwent lower lip cancer resection between January 2014 and December 2017 at the Department of Oral and Maxillofacial Surgery, The Second Xiangya Hospital, Central South University. The shape, volume, and symmetry of the lips were evaluated after the operation. In addition, we classified the large defects of the lower lip and recommended the most appropriate surgical procedures for each type. RESULTS: Seventeen men and two women comprised the study population. The average age of the patients was 63 years (range, 37 to 82 years). All the defects of the lower lip after resection were more than half the lip length. We designed and prepared 2 Abbe flaps located symmetrically at the upper lip to repair the defects of the lower lip, referred to as the "double Abbe flap." The double Abbe flap survived in all patients. The volume, shape, and symmetry of the lips were ideal in most patients, and the degree of mouth opening was acceptable in nearly all patients. CONCLUSIONS: The double Abbe flap is a useful and predictable approach for reconstruction of the lower lip after large-area cancer resection, and it can provide a reference for the repair of lip defects from other causes.

Electromagnetic Wave Absorption Coating Material with Self-Healing Properties.

Electromagnetic wave absorption coatings can effectively minimize electromagnetic radiation and are widely used in the military and civil field. However, even small scratches on the coating can lead to a large decline of absorption ability and bring serious consequences. To enhance the lifetime of electromagnetic wave absorbing coating, a kind of self-healing electromagnetic wave absorbing coating is developed by introducing host-guest interactions between the absorbing fillers and polymer matrix. After being damaged, the cracks on this coating can be healed completely with the aid of small amounts of water. Simultaneously, the electromagnetic absorbing ability of the coating is restored along with the self-healing process.

Semi-IPNs with Moisture-Triggered Shape Memory and Self-Healing Properties.

Moisture or water has the advantages of being green, inexpensive, and moderate. However, it is challenging to endow water-induced shape memory property and self-healing capability to one single polymer because of the conflicting structural requirement of the two types of materials. In this study, this problem is solved through introducing two kinds of supramolecular interactions into semi-interpenetrating polymer networks (semi-IPNs). The hydrogen bonds function as water-sensitive switches, making the materials show moisture-induced shape memory effect. The host-guest interactions (ß-cyclodextrin-adamantane) serve as both permanent phases and self-healing motifs, enabling further increased chain mobility at the cracks and self-healing function. In addition, these polyvinylpyrrolidone/poly(hydroxyethyl methacrylate-co-butyl acrylate) semi-IPNs also show thermosensitive triple-shape memory effect.

A Tri-Stimuli-Responsive Shape-Memory Material Using Host-Guest Interactions as Molecular Switches.

A thermo-, photo- and chemoresponsive shape-memory material is successfully prepared by introducing α-cyclodextrin (αCD) and azobenzene (Azo) into a poly(acrylate acid)/alginate (PAA/Alg) network. The tri-stimuli-responsive formation/dissociation of αCD-Azo acts as molecular switches freezing or increasing the molecular mobility. The resulting film herein can be processed into temporary shapes as needed and recovers its initial shape upon the application of light irradiation, heating, or chemical agent independently. Furthermore, the agar diffusion test suggests that the α-CD-Alg/Azo-PAA has good biocompatibility for L929 fibroblast-like cells.

Longitudinal Contraction Venoplasty in Prevention of Internal Jugular Vein Thrombosis After Free Flap Vascular Anastomosis.

PURPOSE: The vascular anastomosis of free flap with the internal jugular vein stump is susceptible to thrombosis, thus resulting in flap compromise or failure. This study aims to explore the method of longitudinal contraction venoplasty in the prevention of internal jugular vein stump thrombosis after free flap vascular anastomosis and its feasibility. PATIENTS AND METHODS: A retrospective review was performed of 16 patients who underwent internal jugular vein resection because of cancer ablation and longitudinal contraction venoplasty to prevent internal jugular vein stump thrombosis after free flap vascular anastomosis from January 2013 through December 2014 at Second Xiangya Hospital. The methods for longitudinal contraction venoplasty and its efficacy are reported. RESULTS: Venous anastomosis of all flaps was performed with the internal jugular vein stump, and single venous anastomosis was made in all cases. Postoperatively, all flaps survived completely, without vascular compromise. All the patients were followed for approximately 9 to 33 months, and they were satisfied with the esthetic and functional results of the donor and recipient sites after reconstruction. CONCLUSIONS: Longitudinal contraction venoplasty may be an effective new method for prevention of internal jugular vein thrombosis after free flap vascular anastomosis.

[Effect of PEG-6000 Simulation Drought Stress on Physiological Characteristics of Guangfeng Medicinal Yam Plantlets].

Objective: In order to provide the theoretical basis for the Guangfeng medicinal yam( Dioscorea opposita) in field transplanting, the effect of PEG-6000 simulation drought stress on physiological characteristics of Guangfeng medicinal yam plantlets was studied. Methods: Using the method of spectrophotometer,the content of total chlorophyll,soluble total sugar, soluble protein and praline,as well as the activities of SOD,CAT and POD of Guangfeng medicinal yam plantlets were tested under PEG-6000 treatment. Results: Under PEG-6000 simulated drought stress, with the increasing of drought stress and the extension of stress time, the total chlorophyll content of Guangfeng medicinal yam plantlets continued to decline, the content of total soluble sugar, proline and MDA of Guangfeng medicinal yam plantlets significantly increased, the content of soluble protein and the activities of CAT,POD and SOD of Guangfeng medicinal yam plantlets increased at first and then decreased. Conclusion: This study reveals the changes of physiological indices of Guangfeng medicinal yam plantlets under PEG-6000 simulation drought stress, which indicated that Guangfeng medicinal yam plantlets have certain drought tolerance.

Sodium Fluoride Affects DNA Methylation of Imprinted Genes in Mouse Early Embryos.

Fluorine is reported to affect embryonic development, but the underlining mechanism is unclear. The modification of DNA methylation of the H19 and Peg3 genes is important in embryonic development. Therefore, the effect of fluorine on methylation of H19 and Peg3 during early mouse embryos was studied. It was shown that the H19 gene was significantly downmethylated in E2.5, E3.5, and E4.5 embryos from pregnant mice treated with 120 mg/l NaF in drinking water for 48 h. But methylation of both H19 and Peg3 genes was disrupted when the parent male mice were treated with NaF for 35 days. H19 DNA methylation decreased significantly, while Peg3 was almost completely methylated. However, when pregnant mice, mated with NaF-treated male mice, were again treated with NaF for 48 h, either H19 or Peg3 methylation in the embryos decreased significantly. In addition, the mRNA level of H19 considerably increased in E3.5 and E4.5 embryos from NaF-treated pregnant mice. Further, the expression of DNMT1 decreased significantly after NaF treatment. Conclusively, we demonstrated that fluorine may adversely affect early embryonic development by disrupting the methylation of H19 and Peg3 through downregulation of DNMT1.

Preparation of calcium phosphate cement and polymethyl methacrylate for biological composite bone cements.

BACKGROUND: We studied the biological safety, biomechanics, and tissue compatibility of calcium phosphate cement and Polymethyl Methacrylate composite bone cement mixed in different ratios. MATERIAL/METHODS: CPC and PMMA were mixed in different ratios (3:1, 2:1, 1:1, 1:2, 1:5, 1:10, 1:15, and 1:20). PMMA solvent is a general solvent containing a dissolved preparation of the composite bone cement specific to a given specimen to determine biological safety, biomechanics, and tissue compatibility. RESULTS: The CPC/PMMA (33%) group, CPC/PMMA (50%) group, CPC/PMMA (67%) group, and CPC/PMMA (75%) group were more in line with the composite bone cement without cytotoxicity requirements. The compressive strength of the CPC/PMMA (67%) group and CPC/PMMA (75%) group was 20 Mpa-30 Mpa, while that of the CPC/PMMA (4.8%) group, CPC/PMMA (6.25%) group, CPC/PMMA (9.1%) group, CPC/PMMA (16.7%) group, CPC/PMMA (33%) group, and CPC/PMMA (50%) group was 40 Mpa-70 Mpa. Curing time was longer in the CPC group (more than 11 min) and shorter in the PMMA group (less than 2 min). The results of weight loss rate showed that there were no significant differences between the CPC/PMMA group (4.8%, 6.25%, 9.1%, 16.7%, 33%) and PMMA control group (p>0.05). With the decrease of CPC content, the rate of weight loss gradually decreased. CONCLUSIONS: The CPC/PMMA (50%) group, CPC/PMMA (67%) group, and CPC/PMMA (75%) group provide greater variability and selectivity for the composite bone cement in obtaining better application.