Biogenic manganese oxides promote metal(loid) remediation by shaping microbial communities in biological aqua crust.

Biological aqua crust (biogenic aqua crust-BAC) is a potentially sustainable solution for metal(loid) bioremediation in global water using solar energy. However, the key geochemical factors and underlying mechanisms shaping microbial communities in BAC remain poorly understood. The current study aimed at determining the in situ metal(loid) distribution and the key geochemical factors related to microbial community structure and metal(loid)-related genes in BAC of a representative Pb/Zn tailing pond. Here we showed that abundant metal(loid)s (e.g. Pb, As) were co-distributed with Mn/Fe-rich minerals (e.g. biogenic Mn oxide, FeOOH) in BAC. Biogenic Mn oxide (i.e. Mn) was the most dominant factor in shaping microbial community structure in BAC and source tailings. Along with the fact that keystone species (e.g. Burkholderiales, Haliscomenobacter) have the potential to promote Mn ion oxidization and particle agglomeration, as well as Mn is highly associated with metal(loid)-related genes, especially genes related to As redox (e.g. arsC, aoxA), and Cd transport (e.g. zipB), biogenic Mn oxides thus effectively enhance metal(loid) remediation by accelerating the formation of organo-mineral aggregates in biofilm-rich BAC system. Our study indicated that biogenic Mn oxides may play essential roles in facilitating in situ metal(loid) bioremediation in BAC of mine drainage.

Efficient Genome Editing in Most Staphylococcus aureus by Using the Restriction-Modification System Silent CRISPR-Cas9 Toolkit.

Staphylococcus aureus is a clinically important pathogen that threatens human health due to its strong pathogenicity and drug resistance, leading to meningitis, endocarditis, and skin and soft tissue infections. Genetic manipulation in S. aureus is a powerful approach for characterizing the molecular mechanisms of bacterial drug resistance, pathogenicity, and virulence. However, a strong restriction barrier presents a major obstacle to the extensive utilization of genetic manipulation tools in clinical isolates of S. aureus. Here, we constructed a restriction-modification (RM) system silent CRISPR-Cas9 toolkit that synonymously eliminated the type I RM targets of S. aureus from plasmids, downsized plasmids using minicircle technology, and combined with a plasmid artificial modification (PAM) method to circumvent the type II RM system. The RM-silent CRISPR-Cas9 toolkit enables a significant improvement in transformation (105-106 transformants per microgram plasmid in strains we tested) and high-success efficiency editing for gene deletion (knockout strain obtained in one-round electroporation) in a wide range of S. aureus species including clinical isolates of unknown genetic background. The RM-silent CRISPR-Cas9 toolkits could expedite the process of mutant construction in most S. aureus strains, and this approach could be applied to the design of other genetic toolkit plasmids for utilization in a wider range of S. aureus strains.

New Insights into the Accumulation, Transport, and Distribution Mechanisms of Hexafluoropropylene Oxide Homologues, Important Alternatives to Perfluorooctanoic Acid, in Lettuce (Lactuca sativa L.).

Hexafluoropropylene oxide (HFPO) homologues, which are important alternatives to perfluorooctanoic acid, have been frequently identified in crops. Although exposure to HFPO homologues via crops may pose non-negligible threats to humans, their impact on crops is still unknown. In this study, the accumulation, transport, and distribution mechanisms of three HFPO homologues in lettuce were investigated at the plant, tissue, and cell levels. More specifically, HFPO trimer acid and HFPO tetramer acid were primarily fixed in roots and hardly transported to shoots (TF, 0.06-0.63). Conversely, HFPO dimer acid (HFPO-DA) tended to accumulate in lettuce shoots 2-264 times more than the other two homologues, thus resulting in higher estimated daily intake values. Furthermore, the dissolved organic matter derived from root exudate enhanced HFPO-DA uptake by increasing its desorption fractions in the rhizosphere. The transmembrane uptake of HFPO homologues was controlled by means of a transporter-mediated active process involving anion channels, with the uptake of HFPO-DA being additionally facilitated by aquaporins. The higher accumulation of HFPO-DA in shoots was attributed to the larger proportions of HFPO-DA in the soluble fraction (55-74%) and its higher abundance in both vascular tissues and xylem sap. Our findings expand the understanding of the fate of HFPO homologues in soil-crop systems and reveal the underlying mechanisms of the potential exposure risk to HFPO-DA.

Mechanism of arsenic immobilization and biotransformation in the biological aqua crust of mine drainage.

Biological aqua crust (BAC), as a novel biological crust with high arsenic (As) immobilization capacity, might be an ideal nature-based solution for As removal in mine drainage. This study examined the As speciation, binding fraction and biotransformation genes in the BACs to find out the underlying mechanism of As immobilization and biotransformation. Results showed that the BACs could immobilize As from mine drainage up to 55.8 g/kg, and their As immobilization concentrations were 1.3-6.9 times higher than that of sediments. Extremely high As immobilization capacity was attributed to the processes of bioadsorption/absorption and biomineralization driven by Cyanobacteria. The high abundance of As(III) oxidation genes (27.0 %) enhanced microbial As(III) oxidation, resulting in >90.0 % of As(V) with low toxicity and mobility in the BACs. The increase in abundances of aioB, arsP, acr3, arsB, arsC and arsI with As was the key process for microbiota in the BACs for resistance to the As toxicity. In conclusion, our findings innovatively confirmed the potential mechanism of As immobilization and biotransformation mediated by the microbiota in the BACs and highlighted the important role of BACs for As remediation in mine drainage.

Selenium-enriched Bifidobacterium longum DD98 relieves irritable bowel syndrome induced by chronic unpredictable mild stress in mice.

Irritable bowel syndrome (IBS) is a functional intestinal disorder without clear pathological mechanisms. Classical treatments for IBS are not always effective and are usually accompanied by side effects. Selenium-enriched Bifidobacterium longum DD98 (Se-B. longum DD98) is a selenized probiotic strain which has shown many beneficial effects on the gastrointestinal tract, but its effects on IBS and the underlying mechanism are unclear. This study aims to investigate the relieving effects of Se-B. longum DD98 on chronic unpredictable mild stress (CUMS)-induced IBS in mice. The model mice were treated with saline, B. longum DD98, or Se-B. longum DD98 while receiving CUMS. The results suggest that Se-B. longum DD98 significantly relieved the intestinal symptoms of IBS mice and reduced intestinal permeability and inflammation. The depression and anxiety-like behaviors of IBS mice were also improved by Se-B. longum DD98. In addition, the expression of serotonin (5-HT), γ-aminobutyric acid (GABA), neuropeptide Y (NPY), and brain-derived neurotrophic factor (BDNF), which are indicators closely related to mood and brain-gut axis, were up-regulated in mice treated with Se-B. longum DD98. Furthermore, the 16S rRNA sequencing study showed that Se-B. longum DD98 effectively restored the relative abundance of intestinal microbes (e.g., Lactobacillus, Desulfovibrio, Akkermansia) and regulated the impaired diversity of gut microbiota in IBS mice. These results suggest that Se-B. longum DD98 positively acts on the brain-gut axis by improving intestinal functions and regulating mood-associated behaviors and indicators of IBS mice. Therefore, this Se-enriched probiotic strain could be considered a promising candidate for the alleviation of CUMS-induced IBS.

Novel biological aqua crust enhances in situ metal(loid) bioremediation driven by phototrophic/diazotrophic biofilm.

BACKGROUND: Understanding the ecological and environmental functions of phototrophic biofilms in the biological crust is crucial for improving metal(loid) (e.g. Cd, As) bioremediation in mining ecosystems. In this study, in combination with metal(loid) monitoring and metagenomic analysis, we systematically evaluated the effect of biofilm in a novel biological aqua crust (biogenic aqua crust-BAC) on in situ metal(loid) bioremediation of a representative Pb/Zn tailing pond. RESULTS: We observed strong accumulation of potentially bioavailable metal(loid)s and visible phototrophic biofilms in the BAC. Furthermore, dominating taxa Leptolyngbyaceae (10.2-10.4%, Cyanobacteria) and Cytophagales (12.3-22.1%, Bacteroidota) were enriched in biofilm. Along with predominant heterotrophs (e.g. Cytophagales sp.) as well as diazotrophs (e.g. Hyphomonadaceae sp.), autotrophs/diazotrophs (e.g. Leptolyngbyaceae sp.) in phototrophic biofilm enriched the genes encoding extracellular peptidase (e.g. family S9, S1), CAZymes (e.g. CBM50, GT2) and biofilm formation (e.g. OmpR, CRP and LuxS), thus enhancing the capacity of nutrient accumulation and metal(loid) bioremediation in BAC system. CONCLUSIONS: Our study demonstrated that a phototrophic/diazotrophic biofilm constitutes the structured communities containing specific autotrophs (e.g. Leptolyngbyaceae sp.) and heterotrophs (e.g. Cytophagales sp.), which effectively control metal(loid) and nutrient input using solar energy in aquatic environments. Elucidation of the mechanisms of biofilm formation coupled with metal(loid) immobilization in BAC expands the fundamental understanding of the geochemical fate of metal(loid)s, which may be harnessed to enhance in situ metal(loid) bioremediation in the aquatic ecosystem of the mining area. Video Abstract.

The interplay between microalgae and toxic metal(loid)s: mechanisms and implications in AMD phycoremediation coupled with Fe/Mn mineralization.

Acid mine drainage (AMD) is low-pH with high concentration of sulfates and toxic metal(loid)s (e.g. As, Cd, Pb, Cu, Zn), thereby posing a global environmental problem. For decades, microalgae have been used to remediate metal(loid)s in AMD, as they have various adaptive mechanisms for tolerating extreme environmental stress. Their main phycoremediation mechanisms are biosorption, bioaccumulation, coupling with sulfate-reducing bacteria, alkalization, biotransformation, and Fe/Mn mineral formation. This review summarizes how microalgae cope with metal(loid) stress and their specific mechanisms of phycoremediation in AMD. Based on the universal physiological characteristics of microalgae and the properties of their secretions, several Fe/Mn mineralization mechanisms induced by photosynthesis, free radicals, microalgal-bacterial reciprocity, and algal organic matter are proposed. Notably, microalgae can also reduce Fe(III) and inhibit mineralization, which is environmentally unfavorable. Therefore, the comprehensive environmental effects of microalgal co-occurring and cyclical opposing processes must be carefully considered. Using chemical and biological perspectives, this review innovatively proposes several specific processes and mechanisms of Fe/Mn mineralization that are mediated by microalgae, providing a theoretical basis for the geochemistry of metal(loid)s and natural attenuation of pollutants in AMD.

Phenotyping of Methicillin-Resistant Staphylococcus aureus Using a Ratiometric Sensor Array.

Chemical tools capable of classifying multidrug-resistant bacteria (superbugs) can facilitate early-stage disease diagnosis and help guide precision therapy. Here, we report a sensor array that permits the facile phenotyping of methicillin-resistant Staphylococcus aureus (MRSA), a clinically common superbug. The array consists of a panel of eight separate ratiometric fluorescent probes that provide characteristic vibration-induced emission (VIE) profiles. These probes bear a pair of quaternary ammonium salts in different substitution positions around a known VIEgen core. The differences in the substituents result in varying interactions with the negatively charged cell walls of bacteria. This, in turn, dictates the molecular conformation of the probes and affects their blue-to-red fluorescence intensity ratios (ratiometric changes). Within the sensor array, the differences in the ratiometric changes for the probes result in "fingerprints" for MRSA of different genotypes. This allows them to be identified using principal component analysis (PCA) without the need for cell lysis and nucleic acid isolation. The results obtained with the present sensor array agree well with those obtained using polymerase chain reaction (PCR) analysis.

Highly sensitive liquid chromatographic method combined with online ion suppression to remove interfering anions and mass spectrometry for impurity profiling of paromomycin sulfate.

A previously developed high-performance liquid chromatography method combined with pulsed amperometric detection allowed to separate many impurities of paromomycin. However, due to the presence of ion pairing agents and sodium hydroxide in the mobile phase, direct coupling to mass spectrometry for the identification of the chemical structures of the impurities was not an option. Indeed, ion suppression was encountered by trifluoroacetic acid and pentafluoroproponic acid in the mobile phase. A cation self-regenerating suppressor, which was originally designed for increasing analyte conductivity of ammonia and amines analysis in ion chromatography, was coupled between the liquid chromatography and ion trap-time of flight-mass spectrometry and almost all trifluoroacetic acid and pentafluoroproponic acid in the mobile phase was removed. The limit of detection of paromomycin in this integrated system improved significantly to 20 ng/ml (0.4 ng). The chemical structures of 19 impurities were elucidated and seven impurities were reported for the first time.

Targeted photothermal release of antibiotics by a graphene nanoribbon-based supramolecular glycomaterial.

Here, we report the simple construction of a supramolecular glycomaterial for the targeted delivery of antibiotics to P. aeruginosa in a photothermally-controlled manner. A galactose-pyrene conjugate (Gal-pyr) was developed to self-assemble with graphene nanoribbon-based nanowires via π-π stacking to produce a supramolecular glycomaterial, which exhibits a 1250-fold enhanced binding avidity toward a galactose-selective lectin when compared to Gal-pyr. The as-prepared glycomaterial when loaded with an antibiotic that acts as an inhibitor of the bacterial folic acid biosynthetic pathway eradicated P. aeruginosa-derived biofilms under near-infrared light irradiation due to the strong photothermal effect of the nanowires accelerating antibiotic release.

Staphylococcal virulence factor HlgB targets the endoplasmic-reticulum-resident E3 ubiquitin ligase AMFR to promote pneumonia.

Staphylococcus aureus invades cells and persists intracellularly, causing persistent inflammation that is notoriously difficult to treat. Here we investigated host-pathogen interactions underlying intracellular S. aureus infection in macrophages and discovered that the endoplasmic reticulum (ER) is an important cellular compartment for intracellular S. aureus infection. Using CRISPR-Cas9 guide RNA library screening, we determined that the autocrine motility factor receptor (AMFR), an ER-resident E3 ubiquitin ligase, played an essential role in mediating intracellular S. aureus-induced inflammation. AMFR directly interacted with TAK1-binding protein 3 (TAB3) in the ER, inducing K27-linked polyubiquitination of TAB3 on lysine 649 and promoting TAK1 activation. Moreover, the virulence factor γ-haemolysin B (HIgB) of S. aureus bound to the AMFR and regulated TAB3. Our findings highlight an unknown role of AMFR in intracellular S. aureus infection-induced pneumonia and suggest that pharmacological interruption of AMFR-mediated TAB3 signalling cascades and HIgB targeting may prevent invasive staphylococci-mediated pneumonia.

Effects of the fermentation process on the selenite metabolism and selenium incorporation and speciation in a probiotic Bifidobacterium longum.

The influence of the fermentation process on selenite metabolism by a probiotic Bifidobacterium longum DD98 and its consequent enrichment in selenium (Se) were studied. The effects of sodium selenite (Na2SeO3) concentration (18-400 µg/ml), feeding time (12, 16, and 24 h), and fermentation stage (secondary and tertiary fermentation) were evaluated by measuring (i) the total Se content and its distribution between the water-soluble metabolome fraction and the water-insoluble fraction; (ii) the total concentrations of the two principal Se compounds produced: selenomethionine (SeMet) and γ-glutamyl-selenomethionine (γ-Glu-SeMet), and (iii) the speciation of Se in the metabolite fraction. The results revealed that the fermentation process notably changed the Se incorporation into metabolites (γ-Glu-SeMet and free SeMet) and proteins (bound-SeMet) in B. longum DD98. In particular, the production of SeMet was negatively correlated to that of γ-Glu-SeMet when no red precipitate was seen in the bacteria. The study offers a tool for the control of the optimization of the fermentation process towards the desired molecular speciation of the incorporated Se and hence contributes to the production of Se-enriched probiotics with good qualities and bioactivities.

Disturbances of the Gut Microbiota and Microbiota-Derived Metabolites in Inflammatory Bowel Disease.

Inflammatory bowel disease (IBD), comprising Crohn's disease (CD) and ulcerative colitis (UC), is characterized as a chronic and recurrent inflammatory disease whose pathogenesis is still elusive. The gut microbiota exerts important and diverse effects on host physiology through maintaining immune balance and generating health-benefiting metabolites. Many studies have demonstrated that IBD is associated with disturbances in the composition and function of the gut microbiota. Both the abundance and diversity of gut microbiota are dramatically decreased in IBD patients. Furthermore, some particular classes of microbiota-derived metabolites, principally short-chain fatty acids, tryptophan, and its metabolites, and bile acids have also been implicated in the pathogenesis of IBD. In this review, we aim to define the disturbance of gut microbiota and the key classes of microbiota-derived metabolites in IBD pathogenesis. In addition, we also focus on scientific evidence on probiotics, not only on the molecular mechanisms underlying the beneficial effects of probiotics on IBD but also the challenges it faces in safe and appropriate application.

Analysis of impurity profiling of arbekacin sulfate by ion-pair liquid chromatography coupled with pulsed electrochemical detection and online ion suppressor-ion trap-time off light mass spectrometry.

Ion-pair liquid chromatography with pulsed electrochemical detection (LC-PED) was established for the analysis of impurities in arbekacin (ABK) sulfate. APursuit pentafluorophenylpropyl (PFP) column was used as stationary phase. This novel method showed greater separation and sensitivity ability. In a representative ABK sample, 24 impurity peaks were detected in LC-PED, where of only 9 were monitored by a post-column derivatization method prescribed by the Japanese Pharmacopoeia (JP). For identification of the chemical structures of the impurities detected by LC-PED, LC-Mass Spectrometry (MS) was used. Two challenges had to be overcome in this work. The first was the transfer of the MS incompatible mobile phase to an MS compatibleone while maintaining the elution order of the peaks in the chromatograms. Previously reported approaches such as two-dimensional (2D)LC were hardly applicable in this case due to the lack of ultraviolet (UV) absorbing chromophores in ABK and its impurities. The sodium hydroxide solution was replaced by aqueous ammonia to adjust the pH of the mobile phase used in LC-PED. The other challenge encountered was the ion suppression effect caused by trifluoroacetic acid (TFA) and pentafluoroproponic acid (PFPA) in the mobile phase. Some strategies such as "TFA-fixed" and its modifications were tried, but they were inconvenient and severe contamination of the MS was observed. A cationself-regenerating suppressor (CSRS), which was originally designed for increasing analyte conductivityof ammonia and amines analysis in ion chromatography (IC), was coupled between the LC and Ion Trap-Time of Flight (IT-TOF)-MS and almost all TFA and PFPA in the mobile phase were removed. The limit of detection (LOD) of ABK in this integrated system improved significantly to 20 ng/mL. The chemical structures of the 28 impurities were elucidated and 15 impurities were reported for the first time.

Selenium-enriched Bifidobacterium longum DD98 effectively ameliorates dextran sulfate sodium-induced ulcerative colitis in mice.

The pathogenesis of ulcerative colitis (UC) is complicated with impaired intestinal epithelial barrier and imbalanced gut microbiota. Both selenium and probiotics have shown effects in regulating intestinal flora and ameliorating UC. The objective of this study is to investigate the alleviating effects of Selenium-enriched Bifidobacterium longum DD98 (Se-B. longum DD98) on dextran sulfate sodium (DSS)-induced colitis in mice and explore the underlying mechanism. After treatment of B. longum DD98, Se-B. longum DD98, and sulfasalazine for 3 weeks, the disease severity of UC mice was decreased, with colon lengthened and pathological phenotype improved. The expression of pro-inflammatory cytokines and oxidative stress parameters were also decreased. Thus, Se-B. longum DD98 showed a stronger effect on relieving the aforementioned symptoms caused by DSS-induced colitis. Exploration of the potential mechanism demonstrated that Se-B. longum DD98 showed higher activities to suppress the inflammatory response by inhibiting the activation of the toll-like receptor 4 (TLR4), compared to B. longum DD98 and sulfasalazine. Se-B. longum DD98 also significantly improved the intestinal barrier integrity by increasing the expression of tight junction proteins including ZO-1 and occludin. 16S rDNA sequencing analyses showed that Se-B. longum DD98 improved the diversity of the intestinal flora and promoted the abundance of health-benefiting taxa including Lachnospiraceae, Lactobacillaceae, and Prevotellaceae in family level. In conclusion, compared to B. longum DD98 and sulfasalazine, Se-B. longum DD98 showed stronger therapeutic effects on DSS-induced colitis in mice and might be a promising candidate for the treatment of UC.

Anti-bacterial monoclonal antibodies: next generation therapy against superbugs.

Prior to the nineteenth century, infectious disease was one of the leading causes of death. Human life expectancy has roughly doubled over the past century as a result of the development of antibiotics and vaccines. However, the emergence of antibiotic-resistant superbugs brings new challenges. The side effects of broad-spectrum antibiotics, such as causing antimicrobial resistance and destroying the normal flora, often limit their applications. Furthermore, the development of new antibiotics has lagged far behind the emergence and spread of antibiotic resistance. On the other hand, the genome complexity of bacteria makes it difficult to create effective vaccines. Therefore, novel therapeutic agents in supplement to antibiotics and vaccines are urgently needed to improve the treatment of infections. In recent years, monoclonal antibodies (mAbs) have achieved remarkable clinical success in a variety of fields. In the treatment of infectious diseases, mAbs can play functions through multiple mechanisms, including toxins neutralization, virulence factors inhibition, complement-mediated killing activity, and opsonic phagocytosis. Toxins and bacterial surface components are good targets to generate antibodies against. The U.S. FDA has approved three monoclonal antibody drugs, and there are numerous candidates in the preclinical or clinical trial stages. This article reviews recent advances in the research and development of anti-bacterial monoclonal antibody drugs in order to provide a valuable reference for future studies in this area. KEY POINTS: • Novel drugs against antibiotic-resistant superbugs are urgently required • Monoclonal antibodies can treat bacterial infections through multiple mechanisms • There are many anti-bacterial monoclonal antibodies developed in recent years and some candidates have entered the preclinical or clinical stages of development.

Identification of γ-Glutamyl-Selenomethionine as the Principal Selenium Metabolite in a Selenium-Enriched Probiotic, Bifidobacterium longum, by Two-Dimensional HPLC-ICP MS and HPLC-ESI Orbitrap MS.

Selenium (Se)-enriched probiotics are potential sources of organic Se in the human diet, but their application in food is debated because most selenized probiotics and their metabolites are not well-characterized. We analyzed a Se-enriched probiotic, Bifidobacterium longum DD98, to unveil its Se metabolite profiles by two-dimensional high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP MS) and HPLC-electrospray ionization Orbitrap MS. A major Se metabolite was identified as gamma-glutamyl-selenomethionine (γ-Glu-SeMet), which accounted for 42.5 ± 3.4% of water-soluble Se. Most of the remaining Se was present as SeMet (35.2 ± 0.6%) in a free or protein-bound form. In addition, 11 minor Se metabolites were identified, eight of which had not been reported before in probiotics. Six of the identified compounds contained γ-Glu-SeMet as the core structure, constituting a γ-Glu-SeMet family. This study demonstrates the presence of γ-Glu-SeMet in a probiotic, showing a different selenite metabolite pathway from that of Se-enriched yeast, and it offers an alternative and potentially attractive source of organic Se for food and feed supplementation.

Selenium-enriched Bifidobacterium longum DD98 attenuates irinotecan-induced intestinal and hepatic toxicity in vitro and in vivo.

Irinotecan (CPT-11) is a camptothecin chemotherapy drug largely used in treating cancers. However, its strong adverse effects, such as gastrointestinal and hepatic toxicities, tend to reduce the patients' life qualities and to limit the clinical use of CPT-11. The protective roles of selenium (Se) and probiotics against CPT-11-induced toxicity have been widely reported. However, the application of Se-enriched probiotics in the adjuvant therapy of CPT-11 has not been well explored. The purpose of this study is to evaluate the in-vitro and in-vivo effects of Se-enriched Bifidobacterium longum DD98 (Se-B. longum DD98) as a chemotherapy preventive agent on alleviating intestinal and hepatic toxicities induced by CPT-11 chemotherapy. The results showed that Se-B. longum DD98 positively regulated the aberrant cell viability and oxidative stress induced by CPT-11 both in human normal liver (L-02) and rat small intestinal epithelial (IEC-6) cell lines. In vivo experiment revealed that Se-B. longum DD98 significantly attenuated intestinal and hepatic toxicities by ameliorating symptoms such as body weight loss and diarrhea, and by improving the biochemical indicators of hepatotoxicity and oxidative stress. Furthermore, we discovered that the protective effects of Se-B. longum DD98 based largely upon decreasing the pro-inflammatory cytokines IL-1ß and IL-18 and enhancing the expression of tight-junction proteins occludin and ZO-1, as well as restoring the composition and diversity of gut microbiota. Results suggested that Se-B. longum DD98 effectively protected livers and intestines against the CPT-11-induced damages, and therefore, could be considered as a promising adjuvant therapeutic agent with CPT-11 for the cancer treatment.

Directed Expression of Tracheal Antimicrobial Peptide as a Treatment for Bovine-Associated Staphylococcus Aureus-Induced Mastitis in Mice.

Bovine mastitis is perplexing the dairy industry since the initiation of intensive dairy farming, which has caused a reduction in the productivity of cows and an escalation in costs. The use of antibiotics causes a series of problems, especially the formation of bacterial antimicrobial resistance. However, there are limited antibiotic-free therapeutic strategies that can effectively relieve bacterial infection of bovine mammary glands. Hence, in this study, we constructed a mammary gland tissue-specific expression vector carrying the antimicrobial peptide of bovine-derived tracheal antimicrobial peptide (TAP) and evaluated it in both primary bovine mammary epithelial cells (pBMECs) and mice. The results showed that the vector driven by the ß-lactoglobulin gene (BLG) promoter could efficiently direct the expression of TAP in pBMECs and the mammary gland tissue of mice. In addition, significant antibacterial effects were observed in both in vitro and in vivo experiments when introducing this vector to bovine-associated Staphylococcus aureus-treated pBMECs and mice, respectively. This study demonstrated that the mammary gland tissue-specific expression vector could be used to introduce antimicrobial peptide both in in vitro and in vivo and will provide a new therapeutic strategy in the treatment of bovine mastitis.

A novel drug delivery system -- Drug crystallization encapsulated liquid crystal emulsion.

Liquid crystals (LCs) are widely used for drug delivery due to their controlled and sustained drug release properties. In this paper, drug crystallization encapsulated liquid crystal emulsion, a novel drug delivery system, was proposed. The lamellar liquid crystals formed by hydrogenated lecithin, which are similar to the skin stratum corneum lipid structure, are adopted as the drug carrier to encapsulate non-steroidal anti-inflammatory drugs (NSAIDs). As the model drug, ketoprofen exists in the hydrophobic core of emulsion as a drug crystal when squalane is used as the oil phase. The microstructure, sustained drug release behaviors, physicochemical property and biocompatibility of the system were examined by polarized light microscopy, rheological measurements, differential scanning calorimetry, X-ray diffraction, small-angle X-ray scattering, in vitro release study, and in vitro cellular cytotoxicity assay. The results have shown that the novel system lowers the drug crystal melting point and improves the thermal stability of liquid crystal structure. Besides, the excellent biocompatibility and sustained release property through the additional dissolution step of drug crystal show its application potentials in the topical cosmeceuticals. The results will also be helpful for in-depth understanding of the physical state of encapsulated drug in the liquid crystal carrier systems.