New Suggested Enhancing Safe Apneic Time in Edentulous Elderly: A Comparison of Transnasal Humidified Rapid-Insufflation Ventilatory Exchange and Facemask.

BACKGROUND Edentulous elderly patients often face challenges in airway management and are susceptible to hypoxemia. Transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) provides high-flow nasal oxygenation, potentially extending safe apneic time (SAT). This study compared the efficacy of THRIVE versus facemask ventilation in improving oxygenation and extending SAT in edentulous elderly patients. MATERIAL AND METHODS Patients with more than 10 missing teeth and who were over 65 years old were randomly assigned to the facemask group (Group M, n=25) or the THRIVE group (Group T, n=25). Patients in Group M were pre-oxygenated with a facemask (6 L/min, FiO2 100%), while patients in Group T were pre-oxygenated with their mouths closed via THRIVE (30 L/min, FiO2 100%). After anesthesia induction, patients in Group M were ventilated with pressure-controlled ventilation. In Group T, the patient's mouth was kept closed, and the flow rate was adjusted to 70 L/min. Four min after cisatracurium administration, ventilation was stopped in Group M while Group T continued to receive oxygen (70 L/min, FiO2 100%).The primary outcome was SAT, which was attained at 4 min after injection of cisatracurium and ended when SpO2 decreased to 95% or when apneic time reached 480 s. A secondary outcome was the reoxygenation time, defined as the time from the beginning of mechanical ventilation to the time when SpO2 98% was reached. RESULTS An SAT of 480 s was reached by all patients in Group T, but by only 6 patients in Group M (P<0.05). Compared with Group M, the reoxygenation time in Group T was significantly shorter (P<0.05). CONCLUSIONS As compared to facemask, THRIVE can extend the SAT, improve oxygenation, and reduce reoxygenation time.

A self-assembled leucine polymer sensitizes leukemic stem cells to chemotherapy by inhibiting autophagy in acute myeloid leukemia.

Chemotherapy is the primary treatment option for acute myeloid leukemia (AML), but leukemic stem cells (LSC) can survive chemotherapy for disease recurrence and refractory. Here, we found that AML cells obtained from relapsed patients had increased autophagy levels than de novo AML cells. Furthermore, doxorubicin (DOX) treatment stimulated autophagy in LSC by repressing the mTOR pathway, and pharmaceutical inhibition of autophagy rendered chemoresistant LSC sensitive to DOX treatment in MLL-AF9 induced murine AML. Moreover, we developed a self-assembled leucine polymer, which activated mTOR to inhibit autophagy in AML cells by releasing leucine. The leucine polymer loaded DOX (Leu-DOX) induced much less autophagy but more robust apoptosis in AML cells than the DOX treatment. Notably, the leucine polymer and Leu-DOX were specifically taken up by AML cells and LSC but not by normal hematopoietic cells and hematopoietic stem/progenitor cells in the bone marrow. Consequently, Leu-DOX efficiently reduced LSC and prolonged the survival of AML mice, with more limited myeloablation and tissue damage side effects than DOX treatment. Overall, we proposed that the newly developed Leu-DOX is an effective autophagy inhibitor and an ideal drug to efficiently eliminate LSC, thus serving as a revolutionary strategy to enhance the chemotherapy efficacy in AML.

The effect of varying inhaled oxygen concentrations of high-flow nasal cannula oxygen therapy during gastroscopy with propofol sedation in elderly patients: a randomized controlled study.

BACKGROUND: Despite evidence that high-flow nasal cannula oxygen therapy (HFNC) promotes oxygenation, its application in sedated gastroscopy in elderly patients has received little attention. This study investigated the effect of different inhaled oxygen concentrations (FiO2) of HFNC during sedated gastroscopy in elderly patients. METHODS: In a prospective randomized single-blinded study, 369 outpatients undergoing regular gastroscopy with propofol sedation delivered by an anesthesiologist were randomly divided into three groups (n = 123): nasal cannula oxygen group (Group C), 100% FiO2 of HFNC group (Group H100), and 50% FiO2 of HFNC (Group H50). The primary endpoint in this study was the incidence of hypoxia events with pulse oxygen saturation (SpO2) ≤ 92%. The secondary endpoints included the incidence of other varying degrees of hypoxia and adverse events associated with ventilation and hypoxia. RESULTS: The incidence of hypoxia, paradoxical response, choking, jaw lift, and mask ventilation was lower in both Group H100 and Group H50 than in Group C (P < 0.05). Compared with Group H100, Group H50 showed no significant differences in the incidence of hypoxia, jaw lift and mask ventilation, paradoxical response, or choking (P > 0.05). No patients were mechanically ventilated with endotracheal intubation or found to have complications from HFNC. CONCLUSION: HFNC prevented hypoxia during gastroscopy with propofol in elderly patients, and there was no significant difference in the incidence of hypoxia when FiO2 was 50% or 100%. TRIAL REGISTRATION: This single-blind, prospective, randomized controlled trial was approved by the Ethics Committee of Nanjing First Hospital (KY20201102-04) and registered in the China Clinical Trial Center (20/10/2021, ChiCTR2100052144) before patients enrollment. All patients signed an informed consent form.

The Accuracy of a Patient-Specific Three-Dimensional Digital Ostectomy Template for Mandibular Angle Ostectomy.

BACKGROUND: Although three-dimensional (3D)-printed digital ostectomy templates (DOTs) can help surgeons perform mandibular angle ostectomy (MAO) more precisely and safely, the clinical application of such templates is problematic. OBJECTIVES: The aim of this study was to evaluate the accuracy of a novel DOT and improve the precision of MAO. METHODS: A total of 20 patients with a prominent mandibular angle (PMA) were allocated into 2 groups (10 patients per group). A conventional DOT and a novel DOT were applied to guide MAO in Groups A and B, respectively. The mean time taken for curved osteotomy and the volume of postoperative drainage on 1 side within 24 hours were recorded. The deviations between the simulated and postoperative lower border of the mandible were measured on both sides. RESULTS: All the patients were satisfied with the cosmetic outcomes. Statistical results showed that the mean time taken for curved osteotomy was shorter in Group B than in Group A, and that the volume of postoperative drainage on 1 side within 24 hours was similar between the 2 groups. The deviations at the anterior and posterior parts of the inferior border showed that the accuracy of osteotomy was higher in Group B than in Group A, and that there was no significant difference between the 2 groups in the middle part. CONCLUSIONS: The novel DOT is easy to locate and fix tightly, which reduced the operating time and increased the safety and precision of the procedures.

Identification of bacteria associated with periapical abscesses of primary teeth by sequence analysis of 16S rDNA clone libraries.

OBJECTIVE: This study aims to detect the predominant bacteria in acute periapical abscesses of primary teeth using culture-independent molecular methods based on 16S ribosomal DNA cloning. METHODS: Purulent material was collected from nine children diagnosed with abscesses of endodontic origin. DNA was extracted and the 16S rRNA gene amplified with universal primer pairs 27F and 1492R. Amplified genes were cloned, sequenced by Applied Biosystems, and identified by comparison with known 16S rRNA gene sequences. RESULTS: Bacterial DNA was present in all nine purulence samples. A total of 681 clones were classified into 8 phyla, 78 genera, and 125 species/phylotypes. The phyla were Firmicutes, Proteobacteria, Fusobacteria, Bacteroidetes, Actinobacteria, Tenericutes, Deinococcus-Thermus, and Spirochaetes. The most dominant genera were Streptococcus (13.3%), Fusobacterium (11.8%), Parvimonas (7.8%), Prevotella (6.7%), Sphingomonas (5.8%), and Hafnia (5.2%). Fusobacterium nucleatum (11.5%), Parvimonas micra (7.8%), Streptococcus intermedius (6.6%), Sphingomonas echinoides (5.3%), Hafnia alvei (5.2%), and Citrobacter freundii (4.9%) were the most common species/phylotypes. Among these species/phylotypes, F.nucleatum was the most prevalent (7/9). C. freundii, Carnobacterium maltaromaticum, and H. alvei were seldom detected species in acute periapical abscesses but had relatively high abundance and prevalence. CONCLUSION: Acute periapical abscesses are polymicrobial with certain prevalent bacteria, especially anaerobic bacterium. The most predominant and prevalent bacteria of acute periapical abscesses in children was F. nucleatum.

Cephalometric Analysis of Modifications of the Mandible Due to Reduction Mandibuloplasty in Patients With Prominent Mandibular Angle.

Cephalometry has been used to measure hard and soft facial tissues as well as to conduct the ostectomy to determine the characteristics of the prominent mandibular angles (PMA). The changes produced on the mandibles by reduction mandibuloplasty are not known. The objective of the present study was to identify by cephalometric analysis the anatomical changes of the mandibles that occur in patients with PMA after reduction mandibuloplasty. Forty-two patients with PMA were submitted to cephalometric analysis before, 1 week and 6 months after surgery to evaluate the changes of the mandibles produced by reduction mandibuloplasty. Cephalometry was standardized to obtain descriptive measurements of the dimensions of the mandibles. The modifications of the mandibles due to reduction mandibuloplasty showed a significant change obtained by cephalometry. At 1 week after surgery, the average distance between the gonions decreased 17.70 ±â€Š8.46 mm, the average length of the mandibular ramus reduced 5.84 ±â€Š3.26 mm, the average mandibular body length increased 4.61 ±â€Š2.74 mm, the average gonial angle increased 14.78 ±â€Š6.65°, the average mandibular plane angle increased 10.29 ±â€Š3.82°. At 6 months postoperatively, the first 3 linear measurements increased 3.68 ±â€Š2.91, 1.66 ±â€Š2.51, and 2.10 ±â€Š2.37 mm respectively; however, the last 2 angular measurements reduced 2.86 ±â€Š3.02° and 1.77 ±â€Š2.62° respectively. The results demonstrated that reduction mandibuloplasty can modificate mandibular contouring three-dimensionally. The data of 6 months postoperatively compare to those of the beauty people reported in the literature, there were statistically differences between the linear measurements, but no statistically differences between the angular measurements. Despite bone regeneration result in linear or angular measurements change, postoperative angular shape was predominantly maintained, and the preoperative angular prominence did not recur.

Radiotherapy and PGEMOX/GELOX regimen improved prognosis in elderly patients with early-stage extranodal NK/T-cell lymphoma.

The optimal treatment strategy for elderly patients with natural killer/T-cell lymphoma (NKTCL) remains to be established. A total of 63 elderly patients with newly diagnosed NKTCL were retrospectively reviewed. Among the patients with stage I-II disease, 58.3 % received radiotherapy (RT) ± chemotherapy, and 41.7 % received chemotherapy alone. Compared with chemotherapy alone, RT ± chemotherapy elicited a significantly higher overall response rate (ORR) (100 vs. 57.1 %, P < 0.001) and substantially prolonged 5-year overall survival (OS) (55.3 vs. 18.0 %, P < 0.001) in patients with stage I-II disease. Compared with other chemotherapeutic regimens, pegaspargase plus gemcitabine and oxaliplatin (PGEMOX)/L-asparaginase plus gemcitabine and oxaliplatin (GELOX) was associated with a significantly higher ORR (92.9 vs. 51.6 %, P = 0.009) and a significantly improved 5-year OS (78.6 vs. 23.9 %, P = 0.010) in patients with stage I-II disease. Nine patients with stage I-II disease who were treated with PGEMOX/GELOX followed by RT had an encouraging outcome (5-year OS 100 %, 5-year progression-free survival (PFS) 85.7 %), which was superior to that of patients receiving other regimens followed by RT. In conclusion, RT played an important role for elderly patients with early-stage NKTCL, and the PGEMOX/GELOX regimen was superior to other regimens. The combination of them may be a promising treatment option.

Airway management for patients with tracheal stenosis and severe scar contracture of the face and neck via bronchoscopy: a case report.

Both anaesthesiologists and surgeons experience challenges in managing airway stenosis and scar contracture in the face and neck. Herein, we report the case of a 38-year-old woman (BMI 23.1 kg/m2, third-degree burns covering 40% of her body, an American Society of Anaesthesiologists physical status III) with an unusual case of airway constriction. This patient had a predictable difficult airway (mouth opening of 2 cm, bilateral nostril scar hyperplasia, Mallampatti score III, scarring of the head and neck, and severe tracheal stenosis). Tracheal stenosis measuring 5.5 mm in width as observed 8 cm below the glottis, and the bronchoscope could not pass through it. After two failed attempts at laryngeal mask insertion, we decided to instead insert a custom-made tracheal tube under the guidance of a fiberoptic bronchoscope. The operation was successful, and the patient was transferred to the intensive care unit (ICU).

Development and evaluation of a monoclonal antibody-based blocking ELISA to detect antibodies against the E2 protein of bovine viral diarrhea virus-1.

With the rapid development of cattle industry, bovine viral diarrhea virus (BVDV) is becoming widespread in China, which causes serious economic losses to the industry. Effective vaccination and viral surveillance are critical for the prevent and control of BVDV infection. In the present study, the immunogenic domain of E2 protein of BVDV-1 was expressed by prokaryotic pET-28a vector. Monoclonal antibodies (mAbs) against E2 protein were prepared and systemically examined by western blot, immunofluorescence assay, blocking ELISA (bELISA) and virus neutralization test (VNT). The mAb 1E2B3, which showed good reactivity and neutralizing activity to BVDV-1 strains, was selected for ELISA establishment. After a series of screening and optimization, a novel bELISA for highly sensitive and specific detection of BVDV-1 antibodies was established, using HRP-labeled 1E2B3 and recombinant E2 protein. ROC analysis of 91 positive and 84 negative reference bovine serum samples yielded the area under the curve (AUC) of 0.9903. A diagnostic specificity of 96.43 % and a sensitivity of 95.6 % were achieved when the cutoff value was set at 24.31 %. There was no cross reaction to the positive sera of classical swine fever virus (CSFV), BVDV-2, border disease virus (BDV), bovine parainfluenza virus type 3 (BPIV3), infectious bovine rhinotracheitis virus (IBRV), foot-and-mouth disease virus (FMDV), Mycoplasma bovis (M.bovis) and Brucella. The total agreement rate of bELISA with VNT was 93.96 % (249/265). In addition, the result of bELISA was positively correlated with neutralizing antibody titer, and the bELISA could well distinguish the serum samples before and after BVDV vaccination. These results indicate that the established bELISA in this study is specific, sensitive, simple and convenient, which provides technical support for the vaccine efficacy evaluation, prevention and control of BVD in the future.

Effect of supraglottic jet oxygenation and ventilation on hypoxemia in patients undergoing endoscopic surgery with sedation: A meta-analysis of randomized controlled trials.

BACKGROUND: Nasal cannulas and face masks are common oxygenation tools used in conventional oxygen therapy for patients undergoing endoscopic surgery with sedation. However, as a novel supraglottic ventilation technique, the application of supraglottic jet oxygenation and ventilation (SJOV) in endoscopic surgery has not been well established. METHOD: We searched six electronic databases from inception to January 16, 2024, to assess the oxygenation/ventilation efficacy and side effects of the of SJOV in endoscopic surgery. The primary outcome was the incidence of hypoxemia. The secondary outcomes were the incidence of respiratory depression and adverse effects (nasal bleeding, sore throat, and dry mouth). RESULTS: Nine trials involving 2017 patients were included. The results demonstrated that the incidence of hypoxemia was lower in the SJOV group compared with the conventional oxygen therapy (COT) group [9 trails; 2017 patients; risk ratio (RR) = 0.18; 95% confidence interval (CI), (0.11-0.28)]. Subgroup analyses showed that SJOV reduced the incidence of hypoxemia in the high-risk group but had no effect on the low-risk group. The incidence of respiratory depression is lower in SJOV than in COT, but has increased side effects such as dry mouth. There was no statistically significant difference in nose bleeding or sore throat between the two groups. CONCLUSION: Compared with the COT, the SJOV decreased the incidence of hypoxemia in high-risk patients during endoscopic surgery with sedation. There was an increased risk of dry mouth, but not of nose bleeding or sore throat, during endoscopic surgery under sedation.

Exosomes and exosome composite scaffolds in periodontal tissue engineering.

Promoting complete periodontal regeneration of damaged periodontal tissues, including dental cementum, periodontal ligament, and alveolar bone, is one of the challenges in the treatment of periodontitis. Therefore, it is urgent to explore new treatment strategies for periodontitis. Exosomes generated from stem cells are now a promising alternative to stem cell therapy, with therapeutic results comparable to those of their blast cells. It has great potential in regulating immune function, inflammation, microbiota, and tissue regeneration and has shown good effects in periodontal tissue regeneration. In addition, periodontal tissue engineering combines exosomes with biomaterial scaffolds to maximize the therapeutic advantages of exosomes. Therefore, this article reviews the progress, challenges, and prospects of exosome and exosome-loaded composite scaffolds in periodontal regeneration.

Structure regulated 3D flower-like lignin-based anode material for lithium-ion batteries and its storage kinetics.

As a green sustainable material, lignin-derived porous carbon (LPC) exhibits great application potential when used as the anode material in lithium-ion batteries (LIBs), but the applications are limited by the heterogeneity of the lignin precursor. Therefore, it is crucial to reveal the relationship among lignin properties, porous carbon structure and the kinetics of lithium-ion storage. Herein, LPCs from fractionated lignin have been prepared by an eco-friendly and recyclable activator. The structure of the LPCs was regulated by adjusting the molecular weight, linkage abundance and glass transition temperature (Tg) of lignin macromolecules. As the anode material of LIBs, the prepared 3D flower-like LPCE70 could achieve a reversible capacity of 528 mAh g-1 at a current density of 0.2 A g-1 after 200 cycles, 63 % higher than that of commercial graphite. Furthermore, kinetic calculations of lithium-ion storage behavior of LPCs were firstly used to confirm the contribution ratio of diffusion-controlled behavior and capacitive effect. Lignin with a high linkage abundance could yield LPCE70 with the largest interlayer spacing and specific surface area to maximize lithium-ion storage from both diffusion-controlled and capacitive contributions of specific capacities. This work provides a green, facile and effective pathway for value-added utilization of lignin in LIBs.

A Ferroptosis-Inducing and Leukemic Cell-Targeting Drug Nanocarrier Formed by Redox-Responsive Cysteine Polymer for Acute Myeloid Leukemia Therapy.

Ferroptosis is an alternative strategy to overcome chemoresistance, but effective therapeutic approaches to induce ferroptosis for acute myeloid leukemia (AML) treatment are limited. Here, we developed glutathione (GSH)-responsive cysteine polymer-based ferroptosis-inducing nanomedicine (GCFN) as an efficient ferroptosis inducer and chemotherapeutic drug nanocarrier for AML treatment. GCFN depleted intracellular GSH and inhibited glutathione peroxidase 4, a GSH-dependent hydroperoxidase, to cause lipid peroxidation and ferroptosis in AML cells. Furthermore, GCFN-loaded paclitaxel (PTX@GCFN) targeted AML cells and spared normal hematopoietic cells to limit the myeloablation side effects caused by paclitaxel. PTX@GCFN treatment extended the survival of AML mice by specifically releasing paclitaxel and simultaneously inducing ferroptosis in AML cells with restricted myeloablation and tissue damage side effects. Overall, the dual-functional GCFN acts as an effective ferroptosis inducer and a chemotherapeutic drug carrier for AML treatment.

Synthesis and properties of biodegradable poly(ester-urethane)s based on poly(ε-caprolactone) and aliphatic diurethane diisocyanate for long-term implant application: effect of uniform-size hard segment content.

In this article, a series of medical poly(ester-urethane)s (PEUs) with varying uniform-size hard segment content were prepared via one-step chain extension of poly(ε-caprolactone)s with aliphatic urethane diisocyanate, and the corresponding films were obtained by solvent evaporation technique. The chemical structures of polymers were confirmed by 1H NMR, FT-IR and GPC. The effect of uniform-size hard segment content on the physicochemical properties of PEU films, including thermal properties, mechanical properties, crystallization behavior, water-swelling behavior and in vitro degradability, was extensively researched. The PEU films exhibiting similar thermal transition and thermal stability indicated that the uniform-size hard segment content had little effect on the thermal properties. Two obvious glass transition temperatures observed in DSC curves manifested a microphase separation structure, which endowed the PEU films excellent mechanical properties with ultimate stress of 34.6-51.2 MPa and strain at break of 898-1485%. And with the increase of uniform-size hard segment content, the initial modulus and ultimate stress increased, while the strain at break decreased. Due to the compact physical-linking network structure formed by the denser hydrogen bonds, the PEU films exhibited low water-swellability of less than 1.5 wt% and low degradation rate in vitro. The weight loss of the PEU films in degradation test was less than 1 wt% at the first four months and the time of films becoming fragments was more than 15 months. Cytotoxicity test of film extracts was conducted with L929 mouse fibroblasts, and the relative growth rate approached or exceeded 75%, indicating an acceptable cytocompatibility. For the excellent mechanical properties, slow biodegradability, non-toxic degradation products and adequate cytocompatibility, the PEUs containing uniform-size hard segments possess a high potential to be applied as long-term implant biomaterials.

Nanobiopolymers Fabrication and Their Life Cycle Assessments.

Living organisms produced nanopolymers (nanobiopolymers for short), such as nanocellulose, nanochitin, nanosilk, nanostarch, and microbial nanobiopolymers, having received widely scientific and engineering interests in recent years. Compare with petroleum-based polymers, biopolymers are sustainable and biodegradable. The unique structural features that stem from nanosized effects, such as ultrahigh aspect ratio and length-diameter ratio, further endow nanobiopolymers with high transparence and versatile processability. To fabricate these nanobiopolymers, a variety of mechanical, chemical, and synthetic biology techniques have been developed. The applications of the isolated nanobiopolymers have been extended from polymer fillers into wide emerging high-tech fields, such as biomedical devices, bioplastics, display panels, ultrafiltration membranes, energy storage devices, and catalytic supports. Accordingly, in the review, the authors first introduce isolation techniques to fabricate nanocellulose, nanochitin, nanosilk, and nanostarch. Then, the authors summarized the nanobiopolymers produced from biosynthetic pathway, including microbial polyamides, polysaccharides, and polyesters. On the other hand, most of these techniques require high energy consumption and usage of chemical reagents. In this regard, life cycle assessment offered a quantitative route to precisely evaluate and compare environmental benefits of different artificial isolation approaches, which are also summarized in the second section of the review.

Adsorptive performance of coal-based magnetic activated carbon for cyclic volatile methylsiloxanes from landfill leachate.

Bituminous coal-based magnetic activated carbon (MAC) was prepared, characterized, and used successfully for removal of cyclic volatile methylsiloxanes (cVMSs) from treated landfill leachate. Batch adsorption studies were performed at different adsorption dosages and contact times. With adsorptive dosage of 0.75 g/L and contact time of 60 min, the removal efficiencies achieved by MAC for octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) are 100, 82.8, and 71.4%, respectively. The specific magnetization coefficients of MAC before and after adsorption are 4.6 × 10-7 and 5.2 × 10-7 m3/kg, between 1.26 × 10-7 and 3.8 × 10-5 m3/kg, which suggests that MAC can be recycled by the high-intensity magnetic separators.

[Evolution of Extracellular Polymeric Substances of the Activated Sludge with Calcium Ion Addition During Set-up Period of Sequencing Batch Reactors].

Great attention has been paid to accelerate the start-up period and enhance floc properties and structural stability in activated sludge reactors with the aid of inorganic chemical agents such as calcium ion. The laboratory-scale sequencing batch reactors (SBRs) were operated continuously for 35 days to investigate the effect of calcium ion (Ca2+) on the physicochemical properties and evolution of extracellular polymeric substances (EPS) of activated sludge during set-up period. When compared to the control (non-calcium ion addition), the addition of 150 mg·L-1Ca2+ to the influent significantly increased the mixed liquid suspended solids (MLSS) and the mixed liquid volatile suspended solids (MLVSS) by 89.6% and 75.6% on 28 d, respectively, and decreased the sludge volume index (SVI) by 47.9% following SBRs set-up. Compared with the control system, the contents of EPS, polysaccharides (PS) and proteins (PN) were increased by 76.4%, 28.8% and 31.6% under the condition of Ca2+ dosage of 150 mg·L-1. The PS/PN ratio was 68.8 for Ca2+ addition, compared to only 36.6 for the control reactor. Analysis using three-dimensional excitation emission matrix fluorescence spectroscopy and Fourier transform infrared spectrum revealed that Ca2+ addition changed the compositional characteristics of EPS. Results from this study provided a fundamental knowledge basis for the improvement of the settling properties of activated sludge with calcium ion addition.

Enhanced water-solubility, antibacterial activity and biocompatibility upon introducing sulfobetaine and quaternary ammonium to chitosan.

Chitosan (CS) has attracted much attention due to its good antibacterial activity and biocompatibility. However, CS is insoluble in neutral and alkaline aqueous solution, limiting its biomedical application to some extent. To circumvent this drawback, we have synthesized a novel N-quaternary ammonium-O-sulfobetaine-chitosan (Q3BCS) by introducing quaternary ammonium compound (QAC) and sulfobetaine, and its water-solubility, antibacterial activity and biocompatibility were evaluated compare to N-quaternary ammonium chitosan and native CS. The results showed that by introducing QAC, antibacterial activities and water-solubilities increase with degrees of substitution. The largest diameter zone of inhibition (DIZ) was improved from 0 (CS) to 15mm (N-Q3CS). And the water solution became completely transparent from pH 6.5 to pH 11; the maximal waters-solubility was improved from almost 0% (CS) to 113% at pH 7 (N-Q3CS). More importantly, by further introducing sulfobetaine, cell survival rate of Q3BCS increased from 30% (N-Q3CS) to 85% at 2000µg/ml, which is even greater than that of native CS. Furthermore, hemolysis of Q3BCS was dropped sharply from 4.07% (N-Q3CS) to 0.06%, while the water-solution and antibacterial activity were further improved significantly. This work proposes an efficient strategy to prepare CS derivatives with enhanced antibacterial activity, biocompatibility and water-solubility. Additionally, these properties can be finely tailored by changing the feed ratio of CS, glycidyl trimethylammonium chloride and NCO-sulfobetaine.

The simultaneous production of sphingan Ss and poly(R-3-hydroxybutyrate) in Sphingomonas sanxanigenens NX02.

Sphingans and poly(R-3-hydroxybutyrate) (PHB) are both widely used biopolymers produced by bacteria. In the batch fermentation of Sphingomonas sanxanigenens NX02 in a 5L fermenter using glucose as carbon source, ivory colored sphingan Ss production was a growth-associated process with a maximum purified production of 14.88 ± 0.83 g/L, while 6.08 ± 0.23 g/L PHB was simultaneously produced. Sphingan Ss and PHB were separated by a simple dilution, heating and centrifugation or filtration process, and sphingan Ss can be cost-effectively extracted using a small amount of acid rather than multi-fold volumes of alcohols. From ultrathin sections of S. sanxanigenens NX02, we found that the interior space of the cells was filled with PHB granules, and the outside was surrounded by abundant Ss. The purified sphingan Ss can be used as an excellent gelling and emulsifying agent in biotechnology applications such as food, personal care and production processes. Proposed pathways of Ss and PHB biosynthesis from glucose are also presented.