Polylactic Glycolic Acid-Mediated Delivery of Plectasin Derivative NZ2114 in Staphylococcus epidermidis Biofilms.

Antimicrobial peptides (AMPs) are antibiotic candidates; however, their instability and protease susceptibility limit clinical applications. In this study, the polylactic acid-glycolic acid (PLGA)-polyvinyl alcohol (PVA) drug delivery system was screened by orthogonal design using the double emulsion-solvent evaporation method. NZ2114 nanoparticles (NZ2114-NPs) displayed favorable physicochemical properties with a particle size of 178.11 ± 5.23 nm, polydispersity index (PDI) of 0.108 ± 0.10, ζ potential of 4.78 ± 0.67 mV, actual drug-loading rate of 4.07 ± 0.37%, encapsulation rate of 81.46 ± 7.42% and cumulative release rate of 67.75% (120 h) in PBS. The results showed that PLGA encapsulation increased HaCaT cell viability by 20%, peptide retention in 50% serum by 24.12%, and trypsin tolerance by 4.24-fold. Meanwhile, in vitro antimicrobial assays showed that NZ2114-NPs had high inhibitory activity against Staphylococcus epidermidis (S. epidermidis) (4-8 µg/mL). Colony counting and confocal laser scanning microscopy (CLSM) confirmed that NZ2114-NPs were effective in reducing the biofilm thickness and bacterial population of S. epidermidis G4 with a 99% bactericidal rate of persister bacteria, which was significantly better than that of free NZ2114. In conclusion, the results demonstrated that PLGA nanoparticles can be used as a reliable NZ2114 delivery system for the treatment of biofilm infections caused by S. epidermidis.

Development and validation of the Convalescence Symptom Assessment Scale for EsophageCtomy patients.

AIM: A specific, valid and reliable measure is much needed to dynamically assess the recovery of symptoms in oesophagectomy patients. This study describes developing and validating the Convalescent Symptom Assessment Scale for oesophagectomy patients (CSAS_EC). DESIGN: An instrument development and cross-sectional validation study was conducted. METHODS: This study consists of two components: instrument development and psychometric tests. In instrument development, the literature review, qualitative interviews, Delphi method expert consultation and face validation were used to develop and refine scale content. In psychometric tests, the clinical test version scale was used to conduct a cross-sectional in the thoracic surgery department from 17 June to 20 November 2022. The Classical Test Theory and Multidimensional Item Response Theory (MIRT) analyses examined psychometric properties. RESULTS: In instrument development, literature review (n = 20), qualitative interviews (n = 21), expert consultation (n = 12) and pre-survey (n = 15) led to the development of the clinical test version scale. In psychometric tests, a total of 331 participants were enrolled. Confirmatory factor analysis and MIRT analysis verified that a model with 28 items in four dimensions was good. The four dimensions were early recovery symptoms, late recovery symptoms, persistent present symptoms and psychosocial symptoms. The Cronbach's α is 0.827. The validity and reliability were demonstrated to be acceptable. CONCLUSIONS: The CSAS_EC scale can be used as a tool to evaluate the recovery status of oesophagectomy patients.

A latent class analysis of resilience and its association with patient-reported symptoms in patients with esophageal cancer after esophagectomy.

Purpose: To identify the latent classes of resilience in patients with esophageal cancer after esophagectomy and develop a deeper understanding of the association between these classes and patient-reported symptoms. Background: China accounts for more than half of the global burden of esophageal cancer, and patients with esophageal cancer experience numerous symptoms that affect their quality of life and prognosis. Given that resilience is a key element that alleviates the progression of symptoms, it may represent a potential means of to enhancing cancer patients' physical and psychological well-being. Methods: The study was implemented in the thoracic surgery departments of three tertiary hospitals in eastern China. The participants were patients who were still hospitalized after esophagectomy. Data were gathered by self-report questionnaires, and a latent class analysis was utilized to identify different categories of resilience among the patients. Results: A total of 226 patients were recruited. The three classes of resilience identified included high strength and striving (53.5%), medium resilience but weak self-recovery (35.9%), and minimal tenacity and external support (10.6%). Patients with low income (OR = 12.540, p = 0.004) were more likely to be in the minimal tenacity and external support class. Patients without comorbidities (OR = 2.413, p = 0.013) and aged 66-70 years (OR = 4.272, p < 0.001) were more likely to be in the high strength and striving class. The patient-reported symptoms and symptom-related interference of patients after esophagectomy varied considerably among the three categories of resilience. Conclusion: Accurate interventions should be devised and executed according to the features of each type of resilience in patients after esophagectomy to maximize intervention efficacy. These findings highlight the important role of precision nursing.

Enhanced biological activities of coumarin-functionalized polysaccharide derivatives: Chemical modification and activity assessment.

Natural polysaccharides are abundant and renewable resource, but their applications are hampered by limited biological activity. Chemical modification can overcome these drawbacks by altering their structure. Three series of polysaccharide derivatives with coumarins were synthesized to obtain polysaccharide derivatives with enhanced biological activity. The biological activities were tested, including antioxidant property, antifungal property, and antibacterial property. Based on the results, the inhibitory properties of the coumarin-polysaccharide derivatives were significantly improved over the raw polysaccharide. The IC50 of the inhibition of DPPH, ABTS•+, and superoxide (O2•-) radical-scavenging was 0.06-0.15 mg/mL, 2.3-15.9 µg/mL, and 0.03-0.25 mg/mL, respectively. Compared with the raw polysaccharides, coumarin- polysaccharide derivatives exhibited higher efficacy in inhibiting the growth of tested phytopathogens, showing inhibitory indices of 60.0-93.6 % at 1.0 mg/mL. Chitosan derivatives with methyl and chlorine (Compound 10B and 10C) exhibited significant antibacterial activity against S. aureus (MIC = 31.2 µg/mL), E. coli (MIC = 7.8 µg/mL), and V. harveyi (MIC = 15.6 µg/mL), respectively. The results of the cytotoxicity assay showed no observed cytotoxicity when the RAW 264.7 cells were incubated with the synthesized polysaccharide derivatives at the tested concentrations.

Perspective: A proposal on solutions of modern supply chain construction for lactoferrin.

Lactoferrin is an iron-binding glycoprotein of the transferrin family that is found in most bodily fluids of mammals and has a variety of biological and beneficial functions, with great importance in health enhancement as a supplement for humans and other animals. More than 300 t of lactoferrin were produced in 2021, and this number is expected to grow yearly by 10% to 12%, to over 580 t in 2030. With new and important functions of lactoferrin being revealed and studied, focus on its industrial production and application is increasing accordingly. However, lactoferrin is mainly sourced from cheese whey or skim milk by cation-exchange column chromatography, which is a costly and low-quality method. A potential solution for lactoferrin global supply chain construction is proposed in this article as a complement to traditional routes of purification from whey or skim milk. The large-scale production of lactoferrin, mainly by recombinant yeast, mammal, and grain systems, as well as the market niche and product design, are discussed.

Synthesis and biological evaluation of novel 5-substituted/unsubstituted triazolothiadiazines as tubulin depolymerizing and vascular disrupting agents with promising antitumor activity.

A novel series of 5-substituted/unsubstituted [1,2,4]triazolo[3,4-b][1,3,4] thiadiazine compounds has been achieved successfully through chemoselective reduction of the C = N bond, based on our prior work. Initial biological evaluation illustrated that the most active derivative 7j exhibited significant cell growth inhibitory activity toward MCF-7, A549, HCT116, and A2780 with the IC50 values of 0.75, 0.94, 2.90, and 4.15 µM, respectively. Most importantly, all the representative analogs did not demonstrate obvious cytotoxic activity against the non-tumoural cell line HEK-293 (IC50 > 100 µM). The mechanism study revealed that 7j caused the G2 /M phase arrest, induced cell apoptosis in HeLa cells in a concentration-dependent manner, and also showed potent tubulin polymerization inhibitory effect. Meanwhile, 7j exerted significant antivascular activity in the wound-healing and tube formation assays. These observations indicate that 5-unsubstituted 6,7-dihydro-5H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine scaffold might be considered as a potential lead for antitubulin inhibitors to develop highly efficient anticancer agents with potent selectivity over normal human cells.

A randomised controlled trial to improve the resilience of oesophageal cancer survivors in rural China: A study protocol.

AIM: To design a protocol based on the experiences of long-term survivors to facilitate resilience for oesophageal cancer patients in rural China. BACKGROUND: According to the latest Global Cancer Statistics Report, 604,000 new cases of oesophageal cancer were reported, of which over 60% of the disease burden is distributed in China. The incidence of oesophageal cancer in rural China (15.95/100,000) is twice as high as those in urban areas (7.59/100,000). To be sure, resilience can help patients better adapt to post-cancer life. But universal interventions involving improving the resilience of oesophageal cancer patients have much less been explored, especially for rural patients. METHODS: The two-arm, parallel design, non-blinded, randomised controlled trial will be implemented in 86 adults diagnosed with oesophageal cancer and will be randomly assigned to the control group or the intervention group via the blocked randomisation. The intervention group will undergo an intervention with one-on-one guidance from a nurse while viewing a CD of the experiences of long-term survivors with oesophageal cancer in rural areas. Every 2 weeks, a theme session will be introduced, and the entire intervention will continue for 12 weeks. Psychosocial variables (resilience, self-efficacy, coping mode and family support) will be surveyed at baseline, post-intervention and 3 months after the intervention. The paper complies with the Standard Protocol Items: Recommendations for Intervention Trials 2013 and Consolidated Standards of Reporting Trials guidelines for study protocols adapted for designing and reporting parallel group randomised trials. CONCLUSION: The intervention programme transitions from hospitalisation to discharge, which includes one-on-one interventions by medical personnel and a portable CD describing the experiences of long-term survivors with rural oesophageal cancer. Once the intervention's effectiveness is proven, this protocol will provide psychological support for massive oesophageal cancer patients. RELEVANCE TO CLINICAL PRACTICE: The intervention programme may be used as an auxiliary therapy to promote patients' postoperative psychological rehabilitation. This programme has the advantages of being cost-effective, flexible, accessible, and convenient and can be implemented without the limitation of time, place and clinical medical staff. TRIAL REGISTRATION: The Chinese Clinical Trial Registration number is ChiCTR2100050047. Registered on 16 August 2021.

Medical students' academic satisfaction: Social cognitive factors matter.

PURPOSE: Academic satisfaction (AS)-the extent to which people enjoy their role or experiences as medical students-has important implications for well-being and career development. This study explores the relationships between social cognitive factors and AS in a Chinese medical education context. METHOD: The social cognitive model of academic satisfaction (SCMAS) was adopted as the theoretical framework. Within this model, AS is assumed to be related to social cognitive factors-environmental supports, outcome expectations, perceived goal progress and self-efficacy. Demographic variables, financial pressure, college entrance examination scores and social cognitive constructs in SCMAS were collected. To explore the relationships between medical students' social cognitive factors and AS, hierarchical multiple regression analyses were performed. RESULTS: The final sampled data consisted of 127 042 medical students from 119 medical institutions. Demographic variables, financial pressure and college entrance examination scores were first entered in Model 1, explaining 4% of the variance in AS. Social cognitive factors were entered in Model 2, explaining an additional 39% of the variance. Medical students would report higher levels of AS when they (a) held strong confidence in their skills needed for success in studying medicine (ß = 0.20, p < 0.05), (b) had optimistic beliefs about the outcome of studying medicine (ß = 0.40, p < 0.05), (c) felt that they were making good progress in studying medicine (ß = 0.06, p < 0.05) and (d) believed that they received adequate environmental support (ß = 0.25, p < 0.05). The outcome expectations showed the strongest correlation with AS, and each 1-point increase was associated with 0.39 points on the AS score, controlling for all other factors in the model. CONCLUSIONS: Social cognitive factors play an important role in medical students' AS. Intervention programmes or courses aiming to improve medical students' AS are advised to consider social cognitive factors.

Survival experience of patients undergoing oesophagectomy during the recovery period: A meta-synthesis of qualitative studies.

AIMS AND OBJECTIVE: To systematically review and synthesise existing qualitative research evidence describing the survival experience of patients undergoing oesophagectomy during recovery. BACKGROUND: Patients with oesophageal cancer undergoing surgical treatment have severe physical and psychological burdens during the recovery period. Qualitative studies on the survival experience of patients undergoing oesophagectomy are increasing annually, but there is no integration of qualitative evidence. DESIGN: A systematic review and synthesis of qualitative studies were conducted following the ENTREQ. METHODS: Five English (CINAHL, Embase, PubMed, Web of Science and Cochrane Library) and three Chinese (Wanfang, CNKI and VIP) databases were searched for literature on the survival of patients undergoing oesophagectomy during the recovery period from its establishment in April 2022. The quality of the literature was evaluated by the 'Qualitative Research Quality Evaluation Criteria for the JBI Evidence-Based Health Care Centre in Australia', and the data were synthesised by the thematic synthesis method of Thomas and Harden. RESULTS: A total of 18 studies were included, and four themes were identified: physical and mental dual challenges, impaired social functioning, efforts to return to normal life, lack of knowledge and skills in post-discharge care, and thirst for external support. CONCLUSIONS: Future research should focus on the problem of reduced social interaction during the recovery of patients with oesophageal cancer, formulating individualised exercise intervention programs and establishing a sound social support system. RELEVANCE TO CLINICAL PRACTICE: The results of this study provide evidence-based support for nurses to carry out targeted interventions and reference methods for patients with oesophageal cancer to rebuild their lives. NO PATIENT OR PUBLIC CONTRIBUTION: The report was a systematic review and did not involve a population study.

Effects of dietary supplementation of bovine lactoferrin on growth performance, immune function and intestinal health in weaning piglets.

Weaning is a crucial period in the pig's life cycle, which is frequently followed by gastrointestinal (GI) infections, diarrhea and even death. This study focused on the impact of bovine lactoferrin (bLF) supplementation on the intestinal health of weaning piglets. Weaning piglets (Duroc × Landrace × Yorkshire, 23 days) were randomly allocated into four groups, which included negative control group (CON): basic diet; positive control group (ANT): basic diet + 20 mg/kg flavomycin + 100 mg/kg aureomycin; treatment group bLF-A: basic diet + 1 g/kg bLF; treatment group bLF-B: basic diet + 3 g/kg bLF. The result showed that dietary supplementation of bLF can improve growth performance and reduce diarrhea, which exhibits dose-dependency (P < 0.05). Compared with CON group, supplementation with bLF significantly improved immunity, and increased villus height and ratio of villus height/crypt depth at the small intestinal mucosa (P < 0.05). The mRNA expression of claudin-1, occludin and ZO-1 was greatly increased in the ileum of bLF group on days 7 and 14 (P < 0.05). Furthermore, the supplementation of bLF increased the abundance of Lactobacillus and Bifidobacterium and decreased the abundance of Escherichia coli in the cecum on day 7 (P < 0.05). The dietary supplementation of bLF enhanced the growth performance, reduced diarrhea rate in weaning piglets by improving intestinal immunity, morphology and barrier function, balancing intestinal microbiota. And bLF can be a promising feed additive in relieving stress situation of weaning piglets.

Effect of NZ2114 against Streptococcus dysgalactiae biofilms and its application in murine mastitis model.

Bovine mastitis caused by Streptococcus dysgalactiae (S. dysgalactiae) is usually treated with antibiotics, which may potentially increase drug resistance as the abuse. NZ2114, a variant of fungal defensin plectasin, displayed a potent antibacterial activity against S. dysgalactiae. The inhibition/eradication effect of the antimicrobial peptide NZ2114 on the early/mature biofilm of S. dysgalactiae CVCC 3938 was evaluated, as well as the elimination of bacteria in mature biofilms. In this study, NZ2114 displayed potent antibacterial activity against S. dysgalactiae CVCC 3938 and three clinical isolated S. dysgalactiae strains (0.11-0.45 µM). The early biofilm inhibition of S. dysgalactiae CVCC 3938 was 55.5-85.9% after treatment with NZ2114 at concentrations of 1-16 × MIC, which was better than that of vancomycin at the same concentration. The mature biofilm eradication rate was up to 92.7-97.6% with the increasing concentration (2-16 × MIC) of NZ2114, and the eradication rate did not change significantly with further increase of NZ2114 concentration, while the biofilm eradication rate of vancomycin-treated group at the same concentration remained at 92.5%. NZ2114 reduced the number of persister bacteria in biofilm. Scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM) further demonstrated that NZ2114 could effectively reduce the biofilm thickness and bacterial number of S. dysgalactiae CVCC 3938. In vivo therapeutic effect of NZ2114 on murine mastitis model showed that NZ2114 was better than vancomycin in alleviating mammary gland inflammation by regulating cytokines production, inhibiting bacterial proliferation, and reducing the number of mammary gland bacteria. These data suggested that NZ2114 is a potential peptide candidate for the treatment of mastitis.

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.

Combination of Soxhlet extraction and catalytic hydrodebromination for remediation of tetrabromobisphenol A contaminated soil.

As a widely used brominated flame retardants (BFRs), tetrabromobisphenol A (TBBPA) has been detected in various environmental matrices and is known to cause negative effects on both the environment and human health. In this study, a combined method was developed for the abatement of TBBPA contaminated soil based on successive steps of solvent extraction (SE) and catalytic hydrodebromination (HDB) over Pd/C. The results showed that TBBPA could be efficiently extracted from the TBBPA contaminated soil with polar solvents. Subsequently, TBBPA could be completely hydrodebrominated over Pd/C in ethanol, via multistep ultimately yielding bisphenol A. Moreover, NaOH, NH3H2O, and Et3N were more favorable to promote the HDB of 4-TBBPA over Pd/C, and 100% bromide atom removal ratio of TBBPA was achieved within 40 min when [NaOH]0/[organic-Br]0 was more than 1.10 in ethanol. However, the catalytic activity of Pd/C decreased with the repeated use in ethanol. To study the mechanism for this phenomenon, fresh and used catalysts were analyzed by characterization techniques including scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectrometer (EDS). It was found that the deactivation of Pd/C catalyst caused by the gradual accumulation of NaBr could be recovered by washing with water. On the basis of these studies, an effective and practical system for the combined method of SE and catalytic HDB over Pd/C was developed to dispose BFRs contaminated soils.

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-1ß) 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.

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.

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.

Influence of crystallization temperature on fluorescence of n-diamond quantum dots.

Nanodiamonds are popular biological labels because of their superior mechanical and optical properties. Their surfaces bridging the core and surrounding medium play a key role in determining their bio-linkage and photophysical properties. n-diamond is a mysterious carbon allotrope whose crystal structure remains debated. We study the influence of the crystallization temperature on the fluorescence properties of the colloidal n-diamond quantum dots (n-DQDs) with sizes of several nanometers. They exhibit multiband fluorescence across the whole visible region which depends sensitively on the crystallization temperature. Their surfaces turn from hydrophobic ones rich of sp2-bonded carbon into hydrophilic ones rich of carboxyl derivatives and hydroxyl groups as the crystallization temperature increases. The different surface states correlated with the surface structures account for the distinct fluorescence properties of the n-DQDs crystallized at different temperatures. These high-purity ultrasmall n-DQDs with tunable surface chemistry and fluorescence properties are promising multicolor biomarkers and lighting sources.