The production of bacterial cellulose in Gluconacetobacter xylinus regulated by luxR overexpression of quorum sensing system.

Quorum sensing is a mechanism that facilitates cell-to-cell communication. Through signal molecular density for signal recognition, which leads to the regulation of some physiological and biochemical functions. Gluconacetobacter xylinus CGMCC 2955, which produces bacterial cellulose (BC), synthesizes the LuxR protein belonging to the LuxI/LuxR type QS system. Here, a luxR overexpression vector was transformed into G. xylinus CGMCC 2955. The overexpression of luxR increased the yield of BC by 15.6% after 16 days static culture and reduced the cell density by 15.5% after 120-h-agitated culture. The glucose was used up by G. xylinus-pMV24-luxR at 72-h-agitated fermentation, which 12 h earlier than the wild-type (WT). The total N-acylhomoserine lactones (AHL) content of the luxR-overexpressing strain and the WT strain attained 1367.9 ± 57.86 mg/L and 842.9 ± 54.22 mg/L, respectively. The C12-HSL and C14-HSL contents of G. xylinus-pMV24-luxR were 202 ± 21.66 mg/L and 409.6 ± 0.91 mg/L, which were significantly lower than that of WT. In contrast, C6-HSL showed opposite results. The difference of AHL content proved that overexpression of luxR improved the binding of AHL and showed preference for some specific AHL. The metabolic results demonstrated that upon glucose exhaustion, the consumption of gluconic acid was promoted by luxR overexpression, and the content of D- ( +)-trehalose, an antiretrograde metabolite, increased significantly. KEY POINTS: • The overexpression of luxR increased the yield of bacterial cellulose • The content of signal molecules was significantly different • Differential metabolites were involved in multiple metabolic pathways.

Tailoring bacterial cellulose structure through CRISPR interference-mediated downregulation of galU in Komagataeibacter xylinus CGMCC 2955.

Diverse applications of bacterial cellulose (BC) have different requirements in terms of its structural characteristics. culturing Komagataeibacter xylinus CGMCC 2955, BC structure changes with alterations in oxygen tension. Here, the K. xylinus CGMCC 2955 transcriptome was analyzed under different oxygen tensions. Transcriptome and genome analysis indicated that BC structure is related to the rate of BC synthesis and cell growth, and galU is an essential gene that controls the carbon metabolic flux between the BC synthesis pathway and the pentose phosphate (PP) pathway. The CRISPR interference (CRISPRi) system was utilized in K. xylinus CGMCC 2955 to control the expression levels of galU. By overexpressing galU and interfering with different sites of galU sequences using CRISPRi, we obtained strains with varying expression levels of galU (3.20-3014.84%). By testing the characteristics of BC, we found that the porosity of BC (range: 62.99-90.66%) was negative with galU expression levels. However, the crystallinity of BC (range: 56.25-85.99%) was positive with galU expression levels; galU expression levels in engineered strains were lower than those in the control strains. Herein, we propose a new method for regulating the structure of BC to provide a theoretical basis for its application in different fields.

Applications of cellulose and chitin/chitosan derivatives and composites as antibacterial materials: current state and perspectives.

The bacterial infections have always a serious problem to public health. Scientists are developing new antibacterial materials to overcome this problem. Polysaccharides are promising biopolymers due to their diverse biological functions, low toxicity, and high biodegradability. Chitin and chitosan have antibacterial properties due to their cationic nature, while cellulose/bacterial cellulose does not possess any antibacterial activity. Moreover, the insolubility of chitin in common solvents, the poor solubility of chitosan in water, and the low mechanical properties of chitosan have restricted their biomedical applications. In order to solve these problems, chemical modifications such as quaternization, carboxymethylation, cationization, or surface modification of these polymers with different antimicrobial agents, including metal and metal oxide nanoparticles, are carried out to obtain new materials with improved physiochemical and biological properties. This mini review describes the recent progress in such derivatives and composites with potential antibacterial applications.

Identification of Quorum-Sensing Molecules of N-Acyl-Homoserine Lactone in Gluconacetobacter Strains by Liquid Chromatography-Tandem Mass Spectrometry.

Many Gram-negative bacteria can regulate gene expression in a cell density-dependent manner via quorum-sensing systems using N-acyl-homoserine lactones (AHLs), which are typical quorum-sensing signaling molecules, and thus modulate physiological characteristics. N-acyl-homoserine lactones are small chemical molecules produced at low concentrations by bacteria and are, therefore, difficult to detect. Here, a biosensor system method and liquid chromatography-tandem mass spectrometry were combined to detect and assay AHL production. As demonstrated by liquid chromatography-tandem mass spectrometry, Gluconacetobacter xylinus CGMCC No. 2955, a Gram-negative acetic acid-producing bacterium and a typical bacterial cellulose (BC) biosynthesis strain, produces six different AHLs, including N-acetyl-homoserine lactone, N-butanoyl-homoserine lactone, N-hexanoyl-homoserine lactone, N-3-oxo-decanoyl-homoserine lactone, N-dodecanoyl-homoserine lactone, and N-tetradecanoyl-homoserine lactone. Gluconacetobacter sp. strain SX-1, another Gram-negative acetic acid-producing bacterium, which can synthesize BC, produces seven different AHLs including N-acetyl-homoserine lactone, N-butanoyl-homoserine lactone, N-hexanoyl-homoserine lactone, N-3-oxo-octanoyl-homoserine lactone, N-decanoyl-homoserine lactone, N-dodecanoyl-homoserine lactone, and N-tetradecanoyl-homoserine lactone. These results lay the foundation for investigating the relationship between BC biosynthesis and quorum-sensing systems.

Prevalence of infection and reinfection among health care workers in a hospital of Northern China between BA.5/BF.7 and XBB.1.5 wave.

BACKGROUND: To analyze the epidemiological characteristics of the SARS-CoV-2 infection and reinfection associated with the emergence of Omicron variant in Healthcare workers (HCWs). METHODS: We enrolled 760 HCWs who received 2-4 vaccination doses of COVID-19 and followed by BA.5/BF.7 and/or XBB.1.5 breakthrough infections between December 2022 and July 2023. Serum sample from each individual were collected approximately 1,3 and 6 months after last exposure. IgM, IgG and Total antibodies against SARS-CoV-2 were measured by chemiluminescent immunoassay. Meanwhile, we created an Enterprise WeChat link for HCWs to self-report SARS-CoV-2 infections, symptoms and post COVID-19 conditions. RESULTS: Our study revealed that the reinfection rate among HCWs reached 26.1%. The main symptoms were fever (91.2% vs 60.1%), cough (78.8% vs 58.0%), and sore throat (75.4% vs 59.6%) during infection and reinfection in Omicron BA.5/BF.7 and XBB.1.5 wave, and the interval for reinfection ranged from 91 to 210 days (median 152). Fatigue (23.6%), memory loss (18.8%) and coughing (18.6%) were the most prevalent long COVID symptoms, with a higher prevalence among female HCWs. CONCLUSIONS: HCWs reinfection with SARS-CoV-2 causes milder symptoms, but high reinfection rate and short intervals. Strengthen infection prevention and control is crucial to mitigating infection risk and improving health services.

[Clinical Characteristics and Prognostic Relevance of Co-Mutated Genes in Acute Myeloid Leukemia Patients with FLT3 Mutations].

OBJECTIVE: To investigate the clinical characteristics and influence of co-mutated gene on acute myeloid leukemia patients (AML) with FMS-like tyrosine kinase-3 (FLT3) mutations. METHODS: A total of 273 FLT3+ AML patients were enrolled, and the co-mutation gene data of the patients were collected to further analyze the prognosis of the patients. FLT3 and other common mutations were quantified by PCR amplification products direct sequencing and second-generation sequencing (NGS). RESULTS: When patients were divided into FLT3- ITD +, FLT3- TKD +, FLT3- ITD ++TKD + and FLT3- ITD -+TKD - group according to the type of FLT3 mutations, it was found that the frequencies of TET2, GATA2, NRAS and ASXL1 mutation were significantly different among the 4 groups (all P < 0.05). When patients were divided into allelic ratio (AR) ≥0.5 and <0.5 group, it was found that the frequencies of FLT3- ITD +, FLT3 -ITD - +TKD -, NPM1, NRAS and C-kit were significantly different between the two groups (all P < 0.05). When patients were divided into normal and abnormal karyotype group, it was found that the frequencies of FLT3- ITD +, FLT3- TKD +, NPM1, GATA2 and C-kit were significantly different between the two groups (all P < 0.05). The median overall survival (OS) of AML patients with FLT3 -TKD + (including FLT3- ITD ++TKD +) was longer than that of patients with FLT3- ITD + alone (P < 0.05). The OS and relapse-free survival (RFS) of AML patients with FLT3++TET2+ were both shorter than those of patients with FLT3++TET2- (both P < 0.05). CONCLUSION: The mutation frequencies of co-mutated genes are correlated with subtypes of FLT3, karyotype and AR. AML patients with FLT3 -TKD + have longer OS than patients with FLT3- ITD + alone, and patients with co-mutation of TET2 have shorter median OS and RFS.

[Clinical Significance of the Levels of Peripheral Blood Tregs and Cytokines IL-35, TGF-ß and IL-10 in Hemophilia A Patients with Fâ § Inhibitor].

OBJECTIVE: To explore the levels of regulatory T cells (Tregs) and cytokines IL-35, TGF-ß and IL-10 in peripheral blood of hemophilia A(HA) patients with FⅧ inhibitor and their clinical significance. METHODS: 43 HA patients admitted to the Hematology Department of the Affiliated Hospital of North China University of Science and Technology from October 2019 to December 2020 were selected, including 6 cases with FⅧ inhibitor and 37 cases without FⅧ inhibitor. In addition, 20 healthy males who underwent physical examinations were selected as healthy controls. Flow cytometry was used to detect the levels of CD4 + CD25 + CD127 - Tregs in peripheral blood of the HA patients and healthy controls, and ELISA assay was used to detect the expression levels of IL-35, TGF-ß and IL-10 in serum, and their differences between different groups were compared. RESULTS: Compared with the healthy control group, the level of Tregs in HA patients was decreased, and the level of Tregs in the FⅧ inhibitor positive group was the lowest, the difference was statistically significant (P <0.05). There was no significant difference in the expression level of Tregs in HA patients of different severity levels. The serum IL-35, TGF-ß, and IL-10 levels in both FⅧ inhibitor negative and positive groups were significantly lower than those in healthy control group, and those in FⅧ inhibitor positive group were significantly lower than those in FⅧ inhibitor negative group (all P <0.05). CONCLUSION: The decrease of Tregs, IL-35, TGF-ß, and IL-10 levels in HA patients may be related to the formation of FⅧ inhibitors.

A system approach to improving guideline-directed therapy for cardio-renal-metabolic conditions: The "beyond diabetes" initiative.

Objective: Despite demonstrating improvements in cardiovascular disease, kidney disease, and survival outcomes, guideline-directed antihyperglycemic medications such as sodium-glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like-peptide-1 receptor agonists (GLP1-RA), are underutilized. Many obstacles constrain their use including lack of systematic provider and patient education, concern for medication side effects, and patient affordability. Methods: We designed a multimodality, systems-based approach to address these challenges with the goal of increasing medication utilization across the largest healthcare system in New York State. This multispecialty collaborative included provider and patient education, an electronic health record-enabled platform to identify eligible patients, and access to pharmacists for medication guidance and addressing insurance coverage barriers. Surveys were administered following grand rounds lectures and knowledge-based questionnaires were given before and after case-based sessions for housestaff, with results analyzed using a two-sided Student's t-test. Rates of first prescriptions of SGLT2i/GLP1-RA in combined and individual analyses were compared between the pre- and post-education periods (6 months prior to 3/31/2021 and 6 months post 8/19/2021), and the change in prescriptions per 100 eligible-visits was assessed using the incidence density approach. Results: Among grand rounds participants, 69.3% of respondents said they would make changes to their clinical practice. Knowledge increased by 14.7% (p-value <0.001) among housestaff following case-based sessions. An increase in SGLT2i/GLP1-RA prescribing was noted for eligible patients among internal medicine, cardiology, nephrology, and endocrinology providers, from 11.9 per 100 eligible visits in the pre-education period to 14.8 in the post-education period (absolute increase 2.9 [24.4%], incidence risk ratio 1.24 [95% CI 1.18-1.31]; p-value <0.001). Increases in prescribing rates were also seen among individual medical specialties. Conclusions: Our "Beyond Diabetes" initiative showed an improvement in provider knowledge-base and was associated with a modest, but statistically significant increase in the use of SGLT2i and GLP1-RA throughout our healthcare system.

Outcomes of Escalating Immunosuppressive Treatments for Recalcitrant Noninfectious Posterior Scleritis.

INTRODUCTION: This article aimed to summarize the outcomes of escalating immunosuppressive treatments for patients with recalcitrant noninfectious posterior scleritis (PS). METHODS: Clinical records of 16 patients diagnosed with recalcitrant noninfectious PS in the Ocular Immunity and Uveitis Department of Zhongshan Ophthalmic Center from September 2016 to December 2021 were reviewed. Patients were treated with escalating immunosuppressive regimen including corticosteroid, immunosuppressants (IMTs), and adalimumab (ADA). Demographic characteristics and clinical findings at each visit were recorded. The doses of prednisone were analyzed. Main outcomes were corticosteroid-sparing effects, control of inflammation, visual acuity, and safety profile. RESULTS: Ocular pain was the most common finding (100%), followed by the T sign on the B scan (93.8%) and associated anterior scleritis (75.0%). The average initial dose of prednisone was 25.0 mg/day, and tapered to 11.3 and 5.0 mg/day at month 1 and 3, respectively, with statistical significance (p < 0.05). The median overall periods of prednisone tapering to 10, 5, and 0 mg/day were 1.0, 3.0, and 3.0 months, respectively. There were 93.8% of patients receiving prednisone ≤ 10 mg/day and 68.8% of patients off prednisone at last visit. There were 80% of patients treated with IMT and ADA off prednisone at last visit, reaching the highest percentage compared with others. A best-corrected visual acuity of 1.0 or better at last visit was achieved in 10 eyes (62.5%). The escalating treatments showed good safety profile. CONCLUSION: Patients of recalcitrant noninfectious PS benefited from escalating immunosuppressive treatments with favorable visual outcome, in which methotrexate, ciclosporin, and ADA were preferred with good safety.

In situ regulation of bacterial cellulose networks by starch from different sources or amylose/amylopectin content during fermentation.

Bacterial cellulose (BC) is a promising biopolymer, but its three-dimensional structure needs to be controllable to be used in multiple fields. BC has some advantages over other types of cellulose, not only in terms of purity and properties but also in terms of modification (in situ modification) during the synthesis process. Here, starches from different sources or with amylose/amylopectin content were added to the growth medium to regulate the structural properties of BC in-situ. The obtained BC membranes were further modified by superhydrophobic treatment for oil-water separation. Starches alter the viscosity of the medium, thus affecting bacterial motility and cellulose synthesis, and adhere to the microfibers, limiting their further polymerization and ultimately altering the membrane porosity, pore size, and mechanical properties perpendicular to the BC fibril layer direction. The average pore diameter of the BC/PS membrane increased by 1.94 times compared to the initial BC membrane. The chemically modified BC/PS membrane exhibited super-hydrophobicity (water contact angle 167°), high oil-water separation flux (dichloromethane, 23,205 Lm-2 h-1 MPa-1), high separation efficiency (>97%). The study provides a foundation for developing methods to regulate the network structure of BC and broaden its application.

Self-assembly of peptide nanofibers with chirality-encoded antimicrobial activity.

The nanostructured antimicrobial agents, self-assembled by the antimicrobial peptides (AMPs), represent an intriguing platform for the treatment of pathogens. Although the structural characteristics significantly influence antimicrobial functionality, the role of chirality is usually ignored and still unclear. Herein, two homochiral AMPs (all L- or all D-amino acids), including C16-LV4LR4 (LL) and C16-DV4DR4 (DD), and a heterochiral AMP with alternating D-/L-amino acids, C16-DV4LR4 (DL), were self-assembled into left-handed, right-handed, and right-handed helical nanofibers, respectively. The valine configuration determined the supramolecular chirality of the nanofibers. However, the DL molecules exhibited a highly aggregated propensity to form more stable helical nanofibers with a lower degree of twist and a larger helical pitch. This characteristic resulted in the optimal antimicrobial activity of the DL nanofibers against both Gram-negative and Gram-positive bacteria. Furthermore, the membrane permeability assay confirmed the higher activity for damaging the cell membrane by the DL nanofibers. These results demonstrated the significance of molecular chirality in directing the self-assembly of the amphiphilic peptides, eventually affecting their antimicrobial activity. This study opens up the possibility to fabricate promising nanostructured antimicrobial materials by controlling the chirality and structure of the materials.

Doxycycline vs Placebo at 12 Weeks in Patients With Mild Thyroid-Associated Ophthalmopathy: A Randomized Clinical Trial.

Importance: Mild thyroid-associated ophthalmopathy (TAO) negatively impacts quality of life, yet no clinical guidelines for its treatment are available. Existing evidence supports the use of doxycycline in treating mild TAO. Objective: To evaluate the short-term (12 weeks) efficacy of doxycycline in treating mild TAO. Design, Setting, and Participants: In this placebo-controlled multicenter randomized double-masked trial, 148 patients were assessed for eligibility. After exclusions (patients who were pregnant or lactating, had an allergy to tetracyclines, or had uncontrolled systematic diseases), 100 patients with mild TAO (orbital soft tissue affected mildly) at 5 centers in China were enrolled from July 2013 to December 2019 and monitored for 12 weeks. Interventions: Participants were randomly assigned 1:1 to receive doxycycline (50 mg) or placebo once daily for 12 weeks. Main Outcomes and Measures: The primary outcome was the rate of improvement at 12 weeks compared with baseline assessed by a composite indicator of eyelid aperture (reduction ≥2 mm), proptosis (reduction ≥2 mm), ocular motility (increase ≥8°), and Graves ophthalmopathy-specific quality-of-life (GO-QOL) scale score (increase ≥6 points). Adverse events were recorded. Results: A total of 50 participants were assigned to doxycycline and 50 to placebo. The mean (SD) age was 36.7 (9.1) years; 75 participants (75.0%) were female and 100 (100.0%) were Asian. Medication compliance was checked during participant interviews and by counting excess tablets. At week 12, the improvement rate was 38.0% (19 of 50) in the doxycycline group and 16.0% (8 of 50) in the placebo group (difference, 22.0%; 95% CI, 5.0-39.0; P = .01) in the intention-to-treat population. The per-protocol sensitivity analysis showed similar results (39.6% [19 of 48] vs 16.0% [8 of 50]; difference, 23.6%; 95% CI, 6.4-40.8; P = .009). No adverse events other than 1 case of mild gastric acid regurgitation was recorded in either group. Conclusions and Relevance: The results of this study indicate that oral doxycycline, 50 mg daily, resulted in greater improvement of TAO-related symptoms at 12 weeks compared with placebo in patients with mild TAO. These findings support the consideration of doxycycline for mild TAO but should be tempered by recognizing the relatively short follow-up and the size of the cohort. Trial Registration: ClinicalTrials.gov Identifier: NCT02203682.

Preparation and characterization of antibacterial bacterial cellulose/chitosan hydrogels impregnated with silver sulfadiazine.

Hydrogels with pH sensitivity and stable mechanical and antibacterial properties have many desirable qualities and broad applications. A hydrogel based on bacterial cellulose and chitosan, impregnated with silver sulfadiazine (<1% w/w), was prepared using glutaraldehyde as the crosslinking agent. The presence of SSd was confirmed by Fourier transform infrared spectroscopy. Micropore size, swelling ratio, pH- sensitivity, and gram positive and negative antibacterial properties were studied by disk diffusion and colony forming unit. X-ray diffraction confirmed the presence of amorphous and crystalline regions in the hydrogel matrix following addition of SSd. The elemental composition, morphology, and mechanical properties of the hydrogels were characterized. Incorporation of SSd into bacterial cellulose-chitosan hydrogels significantly improved their mechanical and antibacterial properties. The antibacterial activity against E. coli and S. aureus was evaluated and SSd-BC/Ch hydrogels are more toxic to S. aureus than to E. coli. We use FESEM to observe bacterial morphology before and after exposure to SSd-BC/Ch hydrogels. The BacLight LIVE/DEAD membrane permeability kit is used to evaluate the membrane permeability of bacteria. These antibacterial hydrogels have many promising applications in food packaging, tissue engineering, drug delivery, clinical, biotechnological, and biomedical fields.

Sustainable, superhydrophobic membranes based on bacterial cellulose for gravity-driven oil/water separation.

Bacterial cellulose (BC) is a substrate material with high purity and robust mechanical strength, but due to its small pore size and relatively expensive price, it is restricted as an oil-/water separation membrane. In this study, cheaper plant cellulose needle-leaf bleached kraft pulp (NBKP) was added to BC to increase the pore size of the composite membrane, and a superhydrophobic/superoleophilic membrane was prepared for oil-/water separation. The modified membrane surface displayed a petal-like micro-structure and a water contact angle (WCA) of 162.3°, while the oil contact angle was decreased to 0°. What's more, the membrane exhibited excellent oil-/water separation under gravity, recyclability, and a separation efficiency (>95 %), and it was both pH and salt resistant. The membrane also remained durably hydrophobic after 10 separation cycles. And the separation methodology is expected to be highly energy-efficient.

[Expression of Adenovirus-mediated Human Clotting Factor IX Gene in Mouse Adipose-derived Stem Cells].

OBJECTIVE: To investigate the adenovirus-mediated expression of human clotting factor IX (hFIX) gene in mouse adipose-derived stem cells(ADSC). METHODS: The mouse ADSC were isolated and cultured in vitro, the morphology of cells was observed and its growth viability was detected by using CCK-8. Cell surface markers CD29,CD90,CD45 were identified by flow cytometry, and its diferentiation ability was identified by adipogenic and osteogenic induction. Morphological changes was observed and the growth curve should be drawn after transfecting ADSC with adenovirus containing hFIX gene. The expression of hFIX gene was detected by RT-PCR. The expression of hFIX protein in ADSC or in culture supernatant was detected by Western blot. hFIX protein in the supernatant was measured by ELISA, and the clotting factor activity of hFIX in culture supernatant was measured by one-stage method. RESULTS: The in vitro cultured mouse ADSC displayed microspherical shape and strong refractive property. Anchoring growth was lasted for 4-6 hours after planting into culture flask. After cultured for 72 hours, the cells showed long spindle-shaped fibrous and swirling arrangement. The overall growth trend of the third generation ADSC cultured in vitro was S-shaped. The formation of lipid droplets could be observed in the induced cells with Oil red O staining by inverted microscope. After alizarin red staining, the orange-red calcified bone nodes were observed in the induced cells under inverted phase contrast microscope. CD29 (99.91%) and CD90 (99.02%) highly expressed in the third generation of ADSC, but CD45 (0.94%) almost not expressed. RT-PCR showed the hFIX gene could expressed in mouse ADSC. Western blot showed that hFIX protein expressed in both ADSC and culture supernatant. FIX:Ag in cell supernatant was 21.33±3.93 ng/(106 cells.24 h) on the first day, 12.63±0.86 ng/(106 cells.24 h) on the third day and 12.63±2.36 ng/(106 cells.24 h) on the ninth day. FIX:C in culture supernatant was 8.5%. CONCLUSION: Adenovirus-carried hFIX gene can effectively transfect ADSC. ADSC modified by hFIX gene can secrete hFIX protein with coagulation activity.

Permeation of Silver Sulfadiazine Into TEMPO-Oxidized Bacterial Cellulose as an Antibacterial Agent.

Surface oxidation of bacterial cellulose (BC) was done with the TEMPO-mediated oxidation mechanism system. After that, TEMPO-oxidized bacterial cellulose (TOBC) was impregnated with silver sulfadiazine (AgSD) to prepare nanocomposite membranes. Fourier transform infrared spectroscopy (FTIR) was carried out to determine the existence of aldehyde groups on BC nanofibers and X-ray diffraction (XRD) demonstrated the degree of crystallinity. FESEM analysis revealed the impregnation of AgSD nanoparticles at TOBC nanocomposites with the average diameter size ranging from 11 nm to 17.5 nm. The sample OBCS3 showed higher antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli by the disc diffusion method. The results showed AgSD content, dependent antibacterial activity against all tested bacteria, and degree of crystallinity increases with TOBC and AgSD. The main advantage of the applications of TEMPO-mediated oxidation to BC nanofibers is that the crystallinity of BC nanofibers is unchanged and increased after the oxidation. Also enhanced the reactivity of BC as it is one of the most promising method for cellulose fabrication and functionalization. We believe that the novel composite membrane could be a potential candidate for biomedical applications like wound dressing, BC scaffold, and tissue engineering.

Structure-Dependent Antibacterial Activity of Amino Acid-Based Supramolecular Hydrogels.

Bacterial infections are currently a major concern to human health. Amino acid-based supramolecular polymer hydrogels, which boast intrinsic antibacterial activity, are an important solution due to their good biocompatibility, cost effectiveness, and tunable structural properties. Herein, we reported three types of transparent supramolecular hydrogel with intrinsic antibacterial activity from self-assembly of commercially available Fmoc-tryptophan (Fmoc-W), Fmoc-methionine (Fmoc-M), and Fmoc-tyrosine (Fmoc-Y). The resulting hydrogels selectively inhibited the growth of Gram-positive bacteria. Moreover, the order of antibacterial activity was Fmoc-W hydrogel > Fmoc-M hydrogel > Fmoc-Y hydrogel. The critical aggregation concentration (CAC) values were found at concentrations of approximately 0.0293, 0.1172, and 0.4688 mM for Fmoc-W, Fmoc-M, and Fmoc-Y, respectively. Transmission electron microscope (TEM) images revealed rigid and aligned nanofibers for Fmoc-W hydrogel, while flexible nanofibers for Fmoc-M hydrogel and Fmoc-Y hydrogel. The results indicated that stronger aggregation capability of the gelator and the synergistic nanostructural morphology with more rigid and aligned nanofibers can lead to higher antibacterial activity of its corresponding hydrogel. In addition, the molecular arrangements of Fmoc-amino acids in the hydrogels may also contribute to their antibacterial activity. These results can guide the rational design, fabrication, and future application of other self-assembled amino acid-based hydrogels with excellent antibacterial activity.

Development and antibacterial activities of bacterial cellulose/graphene oxide-CuO nanocomposite films.

The absence of antibacterial activity of bacterial cellulose (BC) restricts its applications in the biomedical field. To introduce antimicrobial properties into BC, we studied the synthesis, structure, and antimicrobial properties of a novel nanocomposite film comprising BC, graphene oxide (GO), and copper-oxide (CuO) nanosheets. The nanocomposite film was synthesized by incorporating GO-CuO nanohybrids into BC matrix through homogenized blending. The CuO nanosheets, with a length range of 50 nm-200 nm and width range of 20 nm-50 nm, which were uniformly grown on the GO along with even distribution of GO-CuO nanohybrids on the surface of the cellulose fibers. The nanocomposites displayed better antibacterial activity against gram-positive than gram-negative bacteria. BC/GO-CuO nanocomposites showed higher antibacterial activity than BC/CuO. We also elucidated the mechanism of antibacterial activity of the nanocomposites. Further, the nanocomposites exhibited biocompatibility towards mice fibroblast cells. The nanocomposites might serve as an excellent source for development of antibacterial materials.

[Adenovirus-mediated Expression of B-domain-Deleted Human Coagulation Factor â § in ADSC of SD Rats].

OBJECTIVE: To transinfect SD adipose tissue-derived stem cell (ADSC) in vitro with a recombinant adenoviral vector containing human B-domain-deleted FVIII (BDDhFⅧ), so as to lay the foundation for the treatment of hemophilia A by using ADSC combined with BDDhFⅧ gene. METHODS: ADSCs were isolated from the inguinal adipose tissue of SD rats and passed to third passage for identification. Third passage ADSCs were transfected in vitro with recombinant adenovirus vector Ad-BDDhFⅧ-GFP. The experiments were divided into Ad-BDDhFⅧ-GFP-transfected ADSCs group (A), Ad-GFP-transfected ADSC group (B), and untransfected ADSC group (C). CCK-8 method was used to detect the proliferation of transfected cells in three groups, and the expression level of hFⅧ antigen in cell supernatant was detected by ELISA. RT-PCR and Western blot respectively were used to detect the mRNA and protein expression of BDDhFⅧ in the three groups after transfection. RESULTS: The growth curve of third passage cells isolated and cultured showed an inverted "S" shap; the flow cytometry detection showed the positive expression of CD29, CD90, CD44, and the negative expression of CD45 in third passage cells. After the adipogenic and osteogenic induction, the cells could transformed to adipogenic and osteogenic directions. CCK-8 detection showed that the proliferation of cells in 3 groups not was influenced. ELISA showed that the expression of hFⅧAg in group A was significantly higher than that in group B and C (P＜0.05). RT-PCR showed that compared with group A, there was no target band in B and C groups, and BDDhFⅧ gene was not expressed. The results in group A were consistent with the length of amplified fragments, and BDDhFⅧ target gene was expressed. Western blot analysis showed that the expression of hFⅧ protein in group A was significantly higher than that in group B and C. (P＜0.05). CONCLUSION: Recombinant adenovirus Ad-BDDhFⅧ-GFP can effectively transfect rat ADSC in vitro, which lays an experimental foundation for gene therapy of hemophilia A.

Application of double circular suturing technique (DCST) in repair of giant incision hernias.

BACKGROUND: Our study aims to explore the feasibility and safety of a double circular suturing technique (DCST) in the repair of giant incision hernias. METHODS: The clinical data of 221 patients (95 men and 126 women; the average age was 61.6 years) receiving DCST in the repair of giant incision hernia between January 2010 and December 2018 was analyzed retrospectively. One hundred and five primary and 16 recurrent patients underwent herniorrhaphy with anti-adhesion underlay mesh repair using DCST. RESULTS: All the 221 operations were performed successfully. The average preparation time before the operation and hospital stays were 3.7 days (range, 1-6 days) and 7.5 days (range, 2-16 days), respectively. The average diameter of the hernia ring defect observed intraoperatively was 16.4 cm (range, 12-22 cm). The average time of operation was 83.6 min (range, 43-195 min). There were 2 cases of intestinal fistula, 4 cases of wound infection, 2 cases of mesh infection, 7 cases of serum tumescence, 3 cases of pulmonary infection, and 2 cases of wound dehiscence occurred. One hundred and ninety-five patients were followed up for 6.7 years (range, 0.8-9.5 years) postoperatively. Of them, 9 patients recurred; 14 patients had chronic pain whose visual analog scale (VAS) was 2-4 cm (average 2.7 cm). CONCLUSIONS: With limited preparation time before operations, few postoperative complications, and recurrence rate, DCST in the repair of giant incision hernia is safe and possible clinically.