miR-887-3p Inhibits the Progression of Colorectal Cancer via Downregulating DNMT1 Expression and Regulating P53 Expression

Colorectal cancer (CRC) is the third most diagnosed cancer worldwide and the second leading cause of cancer-related deaths. Many researchers have reported that abnormal microRNAs (miRs) were expressed in CRC and participated in the occurrence and progression of CRC. However, there are few reports of miR-887-3p regulating CRC development. In the current study, we investigated the abnormal expression of miR-887-3p and also demonstrated its regulatory role and detailed molecular mechanism in CRC. Initially, miRNA expression data were obtained from TCGA-COAD that consisted of 453 CRC samples and 8 normal tissue samples. These were downloaded and analyzed to compare the expression level of miR-887-3p in CRC tissues to that in normal tissues. Moreover, 32 pairs of surgically resected CRC tumors and para-cancer tissues from our hospital were collected. Quantitative real-time PCR (qRT-PCR) was performed to detect miR-887-3p expression levels in CRC tissues, para-cancer tissues, several CRC cell lines, and an intestinal epithelial cell line. Following miR-887-3p mimic transfection in colon cancer SW480 cell line, the regulatory roles of miR-887-3p on cell proliferation, apoptosis, invasion, migration, and epithelial-mesenchymal transition (EMT) were detected through CCK-8, flow cytometry, transwell assay, and Western blot. After potential targeting protein was predicted by bioinformatic websites, the luciferase reporter assay and Western blot were used to confirm the target of miR-887-3p. The targeting protein expressions were detected by Western blot and qRT-PCR. The relationship between miR-887-3p level and the effect of miR-887-3p on P53 expression was evaluated by Western blot and qRT-PCR. The effects of miR-887-3p on CRC cell growth in vivo by xenograft tumor experiments were investigated, and Ki-67 in tumor tissue was determined by immunohistochemistry. Results. The COAD data demonstrated that the expression levels of miR-887-3p in CRC clinical sample tissues and cell line cultures were remarkably lower than para-cancer normal tissues and NCM460 cells (normal colonic epithelial cell line). Functional experiments demonstrated that overexpression of miR-887-3p in SW480 cells significantly reduced proliferation, migration, invasion, and EMT, and promoted cancer cell apoptosis. Additionally, Western blot, qRT-PCR, and luciferase reporter assays confirmed that DNMT1 was a downstream target of miR-887-3p. Moreover, the blocking of DNMT1 by miR-887-3p mimics also promoted P53 expression. Finally, overexpression of DNMT1 in SW480 cells could partially reverse the regulatory effect of miR-887-3p mimics on CRC cell development. From in vivo experiments, overexpression of miR-887-3p could inhibit tumor growth in CRC xenograft mice and reduce the Ki-67 level. Conclusion. The microRNA miR-887-3p is a potential biomarker of CRC. It inhibited CRC cell proliferation, invasion, and EMT, and promoted cell apoptosis through targeting and downregulating DNMT1 and promoting P53 expression. Therefore, miR-887-3p may be a good biomarker and therapeutic target for CRC treatment.

Pharmacokinetics and Pharmacodynamics of Fungal Defensin NZX Against Staphylococcus aureus-Induced Mouse Peritonitis Model

Staphylococcus aureus (S. aureus) is one of the most common pathogenic bacteria responsible for causing a life-threatening peritonitis disease. NZX, as a variant of fungal defensin plectasin, displayed potent antibacterial activity against S. aureus. In this study, the antibacterial and resistance characteristics, pharmacokinetics, and pharmacodynamics of NZX against the S. aureus E48 and S. aureus E48-induced mouse peritonitis model were studied, respectively. NZX exhibited a more rapid killing activity to S. aureus (minimal inhibitory concentration, 1 μg/ml) compared with linezolid, ampicillin and daptomycin, and serial passaging of S. aureus E48 for 30 days at 1/2 × MIC, NZX had a lower risk of resistance compared with ampicillin and daptomycin. Also, it displayed a high biocompatibility and tolerance to physiological salt, serum environment, and phagolysosome proteinase environment, except for acid environment in phagolysosome. The murine serum protein-binding rate of NZX was 89.25% measured by ultrafiltration method. Based on the free NZX concentration in serum after tail vein administration, the main pharmacokinetic parameters for T_1/2, C_max, V_d, MRT, and AUC ranged from 0.32 to 0.45 h, 2.85 to 20.55 μg/ml, 1469.10 to 2073.90 ml/kg, 0.32 to 0.56 h, and 1.11 to 8.89 μg.h/ml, respectively. Additionally, the in vivo pharmacodynamics against S. aureus demonstrated that NZX administrated two times by tail vein at 20 mg/kg could rescue all infected mice in the lethal mouse peritonitis model. And NZX treatment (20 mg/kg) significantly reduced CFU counts in the liver, lung, and spleen, especially for intracellular bacteria in the peritoneal fluid, which were similar or superior to those of daptomycin. In vivo efficacies of NZX against total bacteria and intracellular bacteria were significantly correlated with three PK/PD indices of ƒAUC/MIC, ƒC_max/MIC, and ƒT% > MIC analyzed by a sigmoid maximum-effect model. These results showed that NZX may be a potential candidate for treating peritonitis disease caused by intracellular S. aureus.

Sodium-Based Cylindrical Plasmonic Waveguides in the Near-Infrared

Subwavelength optical field confinement and low-loss propagation are of great significance for compact photonic integration. However, the field confinement capability of plasmonic devices is always accompanied by the inherent Ohmic loss. Although recent studies have shown that sodium (Na) exhibits lower loss than noble metals in the near-infrared band, the field confinement ability has not been adequately assessed. Meanwhile, the high chemical reactivity of Na should be regulated for practical application. Two dielectric-coated Na nanowires, consisting of cylindrical Na nanowires with one or two dielectric layers as claddings, are proposed and investigated in this paper. Based on finite element calculations, we thoroughly study the modal fields and low-loss propagation properties of dielectric-coated Na nanowires. The results demonstrate that Na exhibits lower loss and stronger field confinement than the typical plasmonic material silver. These findings indicate the performance of plasmonic devices can be considerably improved by employing the metal Na compared with devices using noble metals, which may promote the applications in subwavelength photonic devices.

Probiotics and synbiotics for preventing postoperative infectious complications in colorectal cancer patients: a systematic review and meta-analysis

BACKGROUND

The health benefits of probiotics and synbiotics in healthy adults are well established, but their role in preventing infectious complications after surgery for colorectal cancer remains controversial. The aim of this meta-analysis was to assess the impact of probiotics/synbiotics on the incidence of infectious complications in patients who had surgery for colorectal cancer.

METHODS

A comprehensive literature search of all randomized control trials (RCTs) was conducted using PubMed, Embase, World Health Organization (WHO) Global Index Medicus, WHO clinical trial registry, and Clinicaltrials.gov. Inclusion criteria included RCTs comparing the use of any strain or dose of a specified probiotic/synbiotic with placebo or a "standard care" control group. The incidence of postoperative infectious complications was analyzed.

RESULTS

Fourteen RCTs involving 1566 patients (502 receiving probiotics, 273 receiving synbiotics, and 791 receiving placebo) were analyzed. Overall, probiotic or synbiotic administration significantly reduced the risk of developing postoperative infectious complications by 37% (relative risk (RR) = 0.63, 95% confidence interval (CI) 0.54-0.74, p < 0.001). Furthermore, when considering the six different types of postoperative infectious complications (septicemia, incision infection, central line infection, pneumonia infection, urinary infection, and incidence of diarrhea), probiotic or synbiotic administration was beneficial in reducing the incidence of each one of them. The quality of evidence was listed below: incidence of diarrhea (high), septicemia (moderate), incision infection (moderate), pneumonia infection (moderate), urinary infection (moderate), and central line infection (low). However, for the main outcome of infectious complications, we found evidence of possible publication bias, although estimates still showed a reduction following trim-and-fill analysis (RR = 0.72, 95% CI 0.62-0.84, p < 0.001).

CONCLUSIONS

The use of probiotic/synbiotic supplementation is associated with a significant reduction in the risk of developing postoperative infectious complications in patients who had surgery for colorectal cancer. Additional studies are needed to confirm the findings due to publication bias and low quality of evidence.

C-terminal mini-PEGylation of a marine peptide N6 had potent antibacterial and anti-inflammatory properties against Escherichia coli and Salmonella strains in vitro and in vivo

Background

Enteropathogenic Escherichia coli and Salmonella pullorum are two important groups of zoonotic pathogens. At present, the treatment of intestinal pathogenic bacteria infection mainly relies on antibiotics, which directly inhibit or kill the pathogenic bacteria. However, due to long-term irrational, excessive use or abuse, bacteria have developed different degrees of drug resistance. N6, an arenicin-3 derivative isolated from the lugworm, has potent antibacterial activity and is poorly resistant to enzymatic hydrolysis and distribution in vivo. Polyethylene glycol (PEG) is an extensively studied polymer and commonly used in protein or peptide drugs to improve their therapeutic potential. Here, we modified the N-/C-terminal or Cys residue of N6 with liner PEGn of different lengths (n = 2, 6,12, and 24), and the effects of PEGylation of N6 on the stability, toxicity, bactericidal mechanism, distribution and efficacy were investigated in vitro and in vivo.

Results

The antimicrobial activity of the peptide showed that PEGylated N6 at the C-terminus (n = 2, N6-COOH-miniPEG) had potent activity against Gram-negative bacteria; PEGylated N6 at the N-terminus and Cys residues showed low or no activity with increasing lengths of PEG. N6-COOH-miniPEG has higher stability in trypsin than the parent peptide-N6. N6-COOH-miniPEG significantly regulated cytokine expression in lipopolysaccharides (LPS)-induced RAW 264.7 cells, and the levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and IL-1β were reduced by 31.21%, 65.62% and 44.12%, respectively, lower than those of N6 (-0.06%, -12.36% and -12.73%); N6-COOH-miniPEG increased the level of IL-10 (37.83%), higher than N6 (-10.21%). The data indicated that N6-COOH-miniPEG has more potent anti-inflammatory and immune-regulatory effect than N6 in LPS-stimulated RAW 264.7 cells. N6-COOH-miniPEG exhibited a much wider biodistribution in mice and prolonged in vivo half-time. FITC-labeled N6-COOH-miniPEG was distributed throughout the body of mice in the range of 0.75 – 2 h after injection, while FITC-labeled N6 only concentrated in the abdominal cavity of mice after injection, and the distribution range was narrow. N6-COOH-miniPEG improved the survival rates of mice challenged with E. coli or S. pullorum, downregulated the levels of TNF-α, IL-6, IL-1β and IL-10 in the serum of LPS-infected mice, and alleviated multiple-organ injuries (the liver, spleen, kidney, and lung), superior to antibiotics, but slightly inferior to N6.

Conclusions

The antibacterial activity, bactericidal mechanism and cytotoxicity of N6-COOH-miniPEG and N6 were similar. N6-COOH-miniPEG has a higher resistance to trysin than N6. The distribution of N6-COOH-miniPEG in mice was superior to that of N6. In exploring the modulatory effects of antimicrobial peptides on cytokines, N6-COOH-miniPEG had stronger anti-inflammatory and immunomodulatory effects than N6. The results suggested that C-terminal PEGylated N6 may provide an opportunity for the development of effective anti-inflammatory and antibacterial peptides.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-022-02534-w.

Antibacterial peptide NZ2114-loaded hydrogel accelerates Staphylococcus aureus-infected wound healing

Wound infection caused by Staphylococcus aureus (S. aureus) is a great challenge which has caused significant burden and economic loss to the medical system. NZ2114, a plectasin-derived peptide, is an antibacterial agent for preventing and treating S. aureus infection, especially for methicillin-resistant S. aureus (MRSA) infection. Here, three-dimensional reticulated antimicrobial peptide (AMP) NZ2114 hydrogels were developed based on hydroxypropyl cellulose (HPC) and sodium alginate (SA); they displayed sustained and stable release properties (97.88 ± 1.79% and 91.1 ± 10.52% release rate in 72 h, respectively) and good short-term cytocompatibility and hemocompatibility. But the HPC-NZ2114 hydrogel had a smaller pore size (diameter 0.832 ± 0.420 μm vs. 3.912 ± 2.881 μm) and better mechanical properties than that of the SA-NZ2114 hydrogel. HPC/SA-NZ2114 hydrogels possess efficient antimicrobial activity in vitro and in vivo. In a full-thickness skin defect model, the wound closure of the 1.024 mg/g HPC-NZ2114 hydrogel group was superior to those of the SA-NZ2114 hydrogel and antibiotic groups on day 7. The HPC-NZ2114 hydrogel accelerated wound healing by reducing inflammation and promoting the production of vascular endothelial growth factor (VEGF), endothelial growth factor (EGF) and angiogenesis (CD31) through histological and immunohistochemistry evaluation. These data indicated that the HPC-NZ2114 hydrogel is an excellent candidate for S. aureus infection wound dressing. KEY POINTS: •NZ2114 hydrogels showed potential in vitro bactericidal activity against S. aureus •NZ2114 hydrogels could release continuously for 72 h and had good biocompatibility •NZ2114 hydrogels could effectively promote S. aureus-infected wound healing.

In Vitro Pharmacodynamics and Bactericidal Mechanism of Fungal Defensin-Derived Peptides NZX and P2 against Streptococcus agalactiae

(1) Background: Based on the hazard of Streptococcus agalactiae to human and animal health and the increasing drug resistance, it is urgent to develop new antimicrobial agents with high bactericidal activity and low drug resistance against S. agalactiae. This study aims to investigate in vitro pharmacodynamics and bactericidal mechanism of fungal defensin-derived peptides NZX and P2 against S. agalactiae. (2) Methods: Minimum inhibitory concentration (MIC) and mutant prevention concentration (MPC) were determined by broth dilution method and AGAR plate dilution method. Cell membrane integrity was determined by flow cytometer. Cell morphological changes were observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). (3) Results: MIC values (NZX: 0.11 μM, P2: 0.91 μM) and MPC (NZX: 1.82 μM) showed their higher antibacterial activity and stronger inhibition ability of drug resistance mutation. The bactericidal mechanism was elucidated that P2 caused S. agalactiae ACCC 61733 cells to deform, bound to the cell wall, and perturbed cell membrane, resulting in K⁺ leakage, membrane hyperpolarization, ATP release, and reduced cell contents. Compared with P2, NZX focuses on the cell wall, and it bound to the cell wall causing cells boundary disappearance. (4) Conclusion: NZX and P2 are promising antimicrobial agents for streptococcicosis treatment.

Experimental Investigation into Flue Gas Water and Waste Heat Recovery Using a Purge Gas Ceramic Membrane Condenser

The direct discharge of wet saturated flue gas from a coal-fired power plant boiler causes a lot of water and waste heat loss. An inorganic ceramic membrane condenser recovers water and waste heat from the flue gas, which has great significance to improve energy utilization efficiency and reduce water consumption. However, the flue gas temperature is relatively low; thus, it is difficult to effectively utilize waste heat. In this paper, it is attempted to use the boiler secondary air as the cooling medium of the ceramic membrane condenser to realize the flue gas waste heat reuse. Based on the above ideas, a purge gas ceramic membrane condenser experimental platform was built for the water and waste heat recovery from the flue gas, and the water and waste heat recovery characteristics and the purge gas outlet parameters were discussed. Simultaneously, the heat transfer resistance and water recovery power consumption are also analyzed. The experimental results show that the water and waste heat recovery characteristics are enhanced with the purge gas flow increases. Increasing the flue gas temperature will increase the water recovery rate and heat recovery power. The ceramic membrane transmission efficiency is a key factor in restricting the actual water recovery efficiency. The purge gas absorbs the water and waste heat from the flue gas, the purge gas temperature and moisture content are significantly increased, and the purge gas relative humidity is also close to saturation. The Biot number of the ceramic membrane condenser is about 3.2 × 10^-3 to 1.9 × 10^-2; thus, the ceramic membrane tube wall thermal resistance can be neglected. There is a temperature difference between the flue gas and the purge gas, and the entropy production value of the ceramic membrane condenser increases with the flue gas temperature increases by the irreversible process.

Fascaplysin derivatives binding to DNA via unique cationic five-ring coplanar backbone showed potent antimicrobial/antibiofilm activity against MRSA in vitro and in vivo

Methicillin-resistant Staphylococcus aureus (MRSA) is considered as one of the most dangerous clinical pathogens. Biofilms forming ability of MRSA is also a major cause of drug resistance. Hence, it is in urgent need to develop novel antibacterial/antibiofilm drugs. Fascaplysin with a unique cationic five-ring coplanar backbone is emerging as a potential antibacterial compound. In this study, aiming at developing novel and more effective agents, a series of fascaplysin derivatives and their corresponding β-carboline precursors have been synthesized. Then their antibacterial/antibiofilm activity and mechanisms against MRSA were investigated for the first time. The results showed that most fascaplysins rather than β-carboline precursors exhibit superior antimicrobial activity against MRSA ATCC43300, demonstrating the important role of cationic five-ring coplanar backbone playing in antibacterial activity. Among them, 14 and 18 are the most potent compounds with MIC value of 0.098 μg/ml (10-fold lower than vancomycin), and 18 featuring the lowest toxicity. Subsequent mechanisms exploration indicates that 18 has relatively stronger ability to destroy bacterial cell wall and membrane, higher binding affinity to bacterial genomic DNA. Molecular docking study revealed that besides the key role of cationic five-ring coplanar backbone, introduction of N-aryl amide at 9-position of fascaplysin promoted the combination of compound 18 and DNA via additional π-π stacking and hydrogen bonding of the naphthyl group. Moreover, fascaplysins could inhibit MRSA biofilm formation in vitro and bacterial infection in vivo. All these results illustrate that fascaplysin derivative 18 is a strong and safe multi-target antibacterial agent, which makes it an attractive candidate for the treatment of MRSA and its biofilm infections.

Resistance response to Arenicin derivatives in Escherichia coli

The rising prevalence of antibiotic resistance poses the greatest health threats. Antimicrobial peptides (AMPs) are regarded as the potentially effective therapy. To avoid current crisis of antibiotic resistance, a comprehensive understanding of AMP resistance is necessary before clinical application. In this study, the development of resistance to the anti-Gram-negative bacteria peptide N6NH₂ (21 residues, β-sheet) was characterized in E. coli ATCC25922. Three N6NH₂-resistant E. coli mutants with 32-fold increase in MIC were isolated by serially passaging bacterial lineages in progressively increasing concentrations of N6NH₂ and we mainly focus on the phenotype of N6NH₂-resistant bacteria different from sensitive bacteria. The results showed that the resistance mechanism was attributed to synergy effect of multiple mechanisms: (i) increase biofilm formation capacity (3 ~ 4-fold); (ii) weaken the affinity of lipopolysaccharide (LPS) with N6NH₂ (3 ~ 8-fold); and (iii) change the cell membrane permeability and potential. Interestingly, a chimeric peptide-G6, also a N6NH₂ analog, which keep the same antibacterial activity to both wild-type and resistant clones (MIC value: 16 μg/mL), could curb N6NH₂-resistant mutants by stronger inhibition of biofilm formation, stronger affinity with LPS, and stronger membrane permeability and depolarization than that of N6NH₂.

Parameter Optimization of a Potted Seedling Tray Prepared from a Mixture of Rice Straw and Fermented Cow Manure Using the Response Surface Methodology

Biomass is generally regarded as a significant renewable resource, which can be used as the raw material for bioproducts. In the study, a mixture of rice straw and fermented cow manure was utilized to produce potted seedling trays, which are biodegradable and environmentally friendly. The effects of process parameters on the quality of final products were assessed by measuring damage resistance (DR) and expansion ratio (ER). Single-factor experiments and the response surface methodology (RSM) were used to optimize process parameters, including moisture content, forming pressure, mass percentage of straw (the ratio of rice straw to the mixture), and forming temperature as variables, and DR and ER of potted seedling trays as responses. The results showed that moisture content had the largest effect on DR and ER, followed by forming pressure, forming temperature, and mass percentage of straw. The optimal conditions were identified as a moisture content of 13%, forming pressure of 124 kN, mass percentage of straw equal to 8%, and forming temperature of 132 °C. There was a good agreement between the experimental data and the predicted results, indicating the reliability of the optimization process. Under the optimal conditions, the effectiveness of the regression model was further validated by the desirability of 0.97. Our findings shed new light on the perfect utilization of straws and animal manure and provided a reliable reference for the preparation of potted seedling trays from other types of biomass produced by agriculture.

Fatty acid modified-antimicrobial peptide analogues with potent antimicrobial activity and topical therapeutic efficacy against Staphylococcus hyicus

There is an urgent need to explore new antimicrobial agents due to the looming threat of bacteria resistance. Bovine lactoferricin (LfcinB), as a multifunctional peptide, has the potential to be a new active drug in the future. In this study, it aims to investigate the effect of fatty acid conjugation on antimicrobial peptide activity and topical therapeutic efficacy in a mouse model infected with Staphylococcus hyicus. Both Lfcin4 and Lfcin5 were conjugated with the unsaturated fatty acid linoleic acid (18-C) at their N-terminus and modified by acylation at the C-terminus. The derived peptides of Lin-Lf4NH2 and Lin-Lf5NH2 showed better antibacterial activity (MICs of 3.27 to 6.64 μM) than their parent peptides (MICs of 1.83 to 59.57 μM). Lin-Lf4NH2 (63.2%, 5 min) and Lin-Lf5NH2 (35.8%, 5 min) could more rapidly penetrate bacterial membrane than Lf4NH2 (2.34%, 5 min) and Lf5NH2 (1.94%, 5 min), which further confirmed by the laser scanning confocal microscopy (LSCM). Electron microscopy observations showed Lin-Lf4NH2 and Lin-Lf5NH2 disrupted S. hyicus cell membranes and led to the leakage of contents. Furthermore, after treatment with Lin-Lf4NH2 and Lin-Lf5NH2, the abscess symptoms of mice were significantly alleviated; the recovery rate of abscesses scope of Lin-Lf4NH2 (73.25%) and Lin-Lf5NH2 (71.71%) were 38.8 and 37.9-fold higher than that of untreated group (1.89%), respectively, and superior to Lf4NH2 (46.87%) and Lf5NH2 (58.75%). They significantly reduced the bacterial load and the levels of the pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) and chemokine (MCP-1) in S. hyicus skin lesions. This study provides evidence that conjugation of a fatty acid to antimicrobial peptides can improve the activity and have potential for topical therapeutic of S. hyicus skin infections. KEY POINTS: • Lin-Lfcin4NH2/Lfcin5NH2 showed stronger antimicrobial activity than parent peptides. • Lin-Lfcin4NH2/Lfcin5NH2 had a more effective ability to destroy bacterial membranes. • Lin-Lfcin4NH2/Lfcin5NH2 showed a topically higher efficacy than parent peptides.

Analysis of risk factors and prognosis of 253 lymph node metastasis in colorectal cancer patients

Background

This study aimed to explore potential risk factors for 253 lymph node metastasis, and to identify the prognostic impact of 253 lymph node metastasis in colorectal cancer patients.

Methods

A retrospective study was conducted of 391 colorectal cancer patients who underwent surgical treatments that included 253 lymph node dissection. Clinicopathological features, molecular indexes and 1-year overall survival rates were analyzed.

Results

Univariate analyses revealed the following risk factors for 253 lymph node metastasis: high preoperative levels of CEA, large tumour max diameters, and numbers of harvested lymph nodes, presence of vessel carcinoma emboli, low level of MSH6 and MLH1 immunohistochemical staining intensity. Multivariate analysis showed that elevated MLH1 immunohistochemical staining intensity was an independent protective factor for 253 lymph node metastasis (OR: 0.969, 95% CI 0.945, 0.994, P = 0.015). A significant difference was found in 1-year overall survival rate between 253 lymph node-positive and lymph node-negative colorectal cancer patients (88.9% vs.75.0%, P < 0.001).

Conclusions

253 lymph node-positive colorectal cancer patients had a worse prognosis than the 253 lymph node-negative patients. 253 lymph node dissection may improve the prognosis of colorectal cancer patients with high risk factors for 253 lymph node metastasis.

Design and Pharmacodynamics of Recombinant Fungus Defensin NZL with Improved Activity against Staphylococcus hyicus In Vitro and In Vivo

Staphylococcus hyicus is recognized as a leading pathogen of exudative epidermitis in modern swine industry. Antimicrobial peptides are attractive candidates for development as potential therapeutics to combat the serious threats of the resistance of S. hyicus. In this study, a series of derivatives were designed based on the NZ2114 template with the aim of obtaining peptides with more potent antimicrobial activity through changing net positive charge or hydrophobicity. Among them, a variant designated as NZL was highly expressed in Pichia pastoris (P. pastoris) with total secreted protein of 1505 mg/L in a 5-L fermenter and exhibited enhanced antimicrobial activity relative to parent peptide NZ2114. Additionally, NZL could kill over 99% of S. hyicus NCTC10350 in vitro within 8 h and in Hacat cells. The results of membrane permeabilization assay, morphological observations, peptide localization assay showed that NZL had potent activity against S. hyicus, which maybe kill S. hyicus through action on the cell wall. NZL also showed an effective therapy in a mouse peritonitis model caused by S. hyicus, superior to NZ2114 or ceftriaxone. Overall, these findings can contribute to explore a novel potential candidate against S. hyicus infections.

The Pharmacodynamics Study of Insect Defensin DLP4 Against Toxigenic Staphylococcus hyicus ACCC 61734 in Vitro and Vivo

Staphylococcus hyicus (S. hyicus), as the main pathogen of exudative epidermitis (EE) in piglet, can cause a wide variety of diseases, ranging from bovine mastitis, chicken arthritis and even human sepsis, which has brought serious threats to animals and human. The potential threat of S. hyicus infection to both public and animal health has aroused great concern. The aim of our study was to explore the efficacy of insect defensin DLP4 against S. hyicus ACCC 61734 in vitro and in vivo. The in vitro efficacies of DLP4 against S. hyicus ACCC 61734 showed high antibacterial activity (0.92 μM), a long postantibiotic effect (9.54 h), a synergistic effect with ceftriaxone, penicillin and amoxicillin, a stable bacteriostatic effect, and intracellular bacteriostatic activity against S. hyicus ACCC 61734 in HaCaT cells. Besides, the antibacterial mechanism of DLP4 against S. hyicus ACCC 61734 was explored for the first time, which indicated that the antibacterial effect of DLP4 was related to its ability to destroy cell wall and generate membrane vesicles. The in vivo therapeutic effect of DLP4 was evaluated through mouse abscess model, and the results showed that DLP4 could effectively alleviate the mouse skin abscess by inhibiting bacterial proliferation and regulating cytokines. This study first demonstrated that DLP4 may be a promising therapeutic agent against S. hyicus ACCC 61734 infection.

Design and High Expression of Non-glycosylated Lysostaphins in Pichia pastoris and Their Pharmacodynamic Study

Lysostaphin is an effective antimicrobial agent to Staphylococcus, especially for the methicillin-resistant Staphylococcus aureus (MRSA) and multidrug-resistant Staphylococcus aureus (MDRSA). In this study, the seven lysostaphin derived mutants (rLys) were designed to overcome the barrier of glycosylation during expression in Pichia pastoris. Among them, 127A and 127A232Q had highest antimicrobial activity (MIC values 0.07–0.3 μM) to S. aureus than others and the commercial lysostaphins (1–15.8 times). There was no glycosylation during the expression in 5-L fermenter level, with the high yield of 1315 mg/L (127A) and 1141 mg/L (127A232Q), respectively. Meanwhile, 127A and 127A232Q effectively killed 99.9% of S. aureus at low concentration (1 × MIC) within 30 min, without the regrowth of pathogen. They also showed low toxicity, high pH and temperature stability. The results of in vivo therapeutic effect of 127A and 127A232Q against high virulent S. aureus CVCC546 showed that 127A and 127A232Q increased the survival rate of infected mice up to 100% at the dose of 10 mg/kg than the untreated group, reduced the bacterial translocation by 5-7 log CFU (over 99%) in organs compared to the untreated group and alleviated multiple-organ injuries (liver, kidney and spleen). These data indicated that the non-glycosylated lysostaphin 127A and 127A232Q may be a promising therapeutic agent against MDR staphylococcal infections.

The effect of different inferior mesenteric artery ligation levels and different lymph node dissection areas on the short- and long-term outcomes of rectal cancer

Background

Surgery is the most effective treatment for rectal cancer patients, but its key steps, including selection of the level of inferior mesenteric artery ligation and removal of 253 lymph nodes, are still inconclusive. This study aimed to analyze the effects of different surgical methods, including levels of ligation (low vs. high) and lymph node dissection areas (D2 vs. D3) on the short-term and long-term outcomes.

Methods

Between March 2014 and August 2018, 253 rectal cancer patients were retrospectively analyzed; 113 patients underwent low ligation D2 lymph node dissection (LLD2), 75 patients underwent low ligation D3 lymph node dissection (LLD3), and 65 patients underwent high ligation (HL). We compared the short-term and long-term outcomes among the different groups.

Results

There were no significant differences among the groups in terms of the intraoperative variables, including operative time, blood transfusion, and conversion from laparoscopic to open surgery. The median blood loss was significantly lower in LLD3 (50 mL) than in LLD2 (100 mL) and HL (100 mL), but it was not significantly different between LLD2 and HL. There were no significant differences among the LLD2, LLD3, and HL groups in the incidence of postoperative complications (9.7% vs. 12.0% vs. 10.8%, respectively) and hospital stay (14 vs. 15 vs. 14, respectively). The anastomotic leakage Clavien-Dindo grade was significantly lower with LLD2 and LLD3 than with HL, but it was the same between LLD2 and LLD3. The total number of lymph nodes harvested in the LLD3 group (n=14) was higher than that in the LLD2 group (n=12), but it was not significantly different than that in the HL group (n=13). There were no significant differences among the groups in terms of 3-year overall survival rate and disease-free survival rate.

Conclusions

Low ligation was similar to HL in terms of major intraoperative and postoperative parameters, but it can reduce the severity of anastomotic leakage to a certain extent. D3 lymph node dissection can increase the total number of lymph nodes harvested, but it did not improve long-term prognosis.

Marine Peptide-N6NH2 and Its Derivative-GUON6NH2 Have Potent Antimicrobial Activity Against Intracellular Edwardsiella tarda in vitro and in vivo

Edwardsiella tarda is a facultative intracellular pathogen in humans and animals. There is no effective way except vaccine candidates to eradicate intracellular E. tarda. In this study, four derivatives of marine peptide-N6NH2 were designed by an introduction of unnatural residues or substitution of natural ones, and their intracellular activities against E. tarda were evaluated in macrophages and in mice, respectively. The minimum inhibitory concentration (MIC) value of N6NH2 and GUON6NH2 against E. tarda was 8 μg/mL. GUON6NH2 showed higher stability to trypsin, lower toxicity (<1%) and longer post-antibiotic effect (PAE) than N6NH2 and other derivatives. Antibacterial mechanism results showed that GUON6NH2 could bind to LPS and destroyed outer/inner cell membranes of E. tarda, superior to N6NH2 and norfloxacin. Both N6NH2 and GUON6NH2 were internalized into macrophages mainly via lipid rafts, micropinocytosis, and microtubule polymerization, respectively, and distributed in the cytoplasm. The intracellular inhibition rate of GUON6NH2 against E. tarda was 97.05–100%, higher than that in case of N6NH2 (96.82–100%). In the E. tarda-induced peritonitis mouse model, after treatment with of 1 μmol/kg N6NH2 and GUON6NH2, intracellular bacterial numbers were reduced by 1.54- and 1.97-Log₁₀ CFU, respectively, higher than norfloxacin (0.35-Log₁₀ CFU). These results suggest that GUON6NH2 may be an excellent candidate for novel antimicrobial agents to treat infectious diseases caused by intracellular E. tarda.

A recombinant fungal defensin-like peptide-P2 combats Streptococcus dysgalactiae and biofilms

Streptococcus dysgalactiae, considered one of the main pathogens that causes bovine mastitis, is a serious threat to humans and animals. However, the excessive use of antibiotics and the characteristic of S. dysgalactiae forming biofilms in mastitic teat canal have serious clinical implications. In this study, in vivo and in vitro multiple mechanisms of action of P2, a mutant of fungal defensin plectasin, against S. dysgalactiae were systematically and comprehensively investigated for the first time. P2 showed potent antibacterial activity against S. dysgalactiae (minimum inhibitory concentration, MIC = 0.23-0.46 μM) and rapid bactericidal action by 3.0 lg units reduction in 2-4 h. No resistant mutants appeared after 30-d serial passage of S. dysgalactiae in the presence of P2. The results of electron microscopy and flow cytometer showed that P2 induced membrane damage of S. dysgalactiae, causing the leakage of cellular content and eventually cell death. Besides, P2 effectively inhibited early biofilm formation, eradicated mature biofilms, and killed 99.9% persisters which were resistant to 100 × MIC vancomycin; and confocal laser scanning microscopy (CLSM) also revealed the potent antibacterial and antibiofilm activity of P2 (the thickness of biofilm reduced from 18.82 to 7.94 μm). The in vivo therapeutic effect of P2 in mouse mastitis model showed that it decreased the number of mammary bacteria and alleviated breast inflammation by regulating cytokines and inhibiting bacterial proliferation, which were superior to vancomycin. These data indicated that P2 maybe a potential candidate peptide for mastitis treatment of S. dysgalactiae infections. KEY POINTS: •P2 showed potential in vitro antibacterial characteristics towards S. dysgalactiae. •P2 eradicated biofilms, killed persisters, and induced cell death of S. dysgalactiae. •P2 could effectively protect mice from S. dysgalactiae infection in gland.

A prospective on multiple biological activities of lactoferrin contributing to piglet welfare

Piglets, especially weaning piglets, show a lower level of immunity and higher morbidity and mortality, owing to their rapid growth, physiological immaturity, and gradual reduction of maternal antibodies, which seriously affects their growth and thus, value. It is important that piglets adapt to nutrient digestion and absorption and develop sound intestinal function and colonization with gut microbiota as soon as possible during their early life stage. Lactoferrin is a natural glycoprotein polypeptide that is part of the transferrin family. It is widely found in mucosal secretions such as saliva and tears, and most highly in milk and colostrum. As a multifunctional bioactive protein and a recommended food additive, lactoferrin is a potential alternative therapy to antibiotics and health promoting additive for piglet nutrition and development. It is expected that lactoferrin, as a natural food additive, could play an important role in maintaining pig health and development. This review examines the following known beneficial effects of lactoferrin: improves the digestion and capacity for absorption in the intestinal tract; promotes the absorption of iron and reduces the incidence of iron deficiency anemia; regulates intestinal function and helps to balance the microbial biota; and enhances the resistance to disease of the piglets via modulating and enhancing the immune system.

Theoretical Analysis of Terahertz Dielectric-Loaded Graphene Waveguide

The waveguiding of terahertz surface plasmons by a GaAs strip-loaded graphene waveguide is investigated based on the effective-index method and the finite element method. Modal properties of the effective mode index, modal loss, and cut-off characteristics of higher order modes are investigated. By modulating the Fermi level, the modal properties of the fundamental mode could be adjusted. The accuracy of the effective-index method is verified by a comparison between the analytical results and numerical simulations. Besides the modal properties, the crosstalk between the adjacent waveguides, which determines the device integration density, is studied. The findings show that the effective-index method is highly valid for analyzing dielectric-loaded graphene plasmon waveguides in the terahertz region and may have potential applications in subwavelength tunable integrated photonic devices.

The effect of strain on water dissociation on reduced rutile TiO2(110) surface

The effect of external uniaxial strain on water dissociation on a reduced rutile TiO₂(110) surface has been theoretically studied using first-principles calculations. We find that when the tensile strain along [11̄0] is applied, the energy barrier of water dissociation substantially decreases with the increase of strain. In particular, water almost automatically dissociates when the strain is larger than 3%. Besides, the water dissociation mechanism changes from indirect to direct dissociation when the compressive strain is larger than 1.3% along [11̄0] or 3% along [001]. The results strongly suggest that it is feasible to engineer the water dissociation on the reduced rutile TiO₂(110) surface using external strain.

The tensile strain along [11̄0] on the reduced TiO₂(110) surface can greatly promote the dissociation of water, the compressive strain along [001] and [11̄0] can change the dissociation mechanisms.