Remodeling of the Intra-Conduit Inflammatory Microenvironment to Improve Peripheral Nerve Regeneration with a Neuromechanical Matching Protein-Based Conduit

Peripheral nerve injury (PNI) remains a challenging area in regenerative medicine. Nerve guide conduit (NGC) transplantation is a common treatment for PNI, but the prognosis of NGC treatment is unsatisfactory due to 1) neuromechanical unmatching and 2) the intra-conduit inflammatory microenvironment (IME) resulting from Schwann cell pyroptosis and inflammatory-polarized macrophages. A neuromechanically matched NGC composed of regenerated silk fibroin (RSF) loaded with poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (P:P) and dimethyl fumarate (DMF) are designed, which exhibits a matched elastic modulus (25.1 ± 3.5 MPa) for the peripheral nerve and the highest 80% elongation at break, better than most protein-based conduits. Moreover, the NGC can gradually regulate the intra-conduit IME by releasing DMF and monitoring sciatic nerve movements via piezoresistive sensing. The combination of NGC and electrical stimulation modulates the IME to support PNI regeneration by synergistically inhibiting Schwann cell pyroptosis and reducing inflammatory factor release, shifting macrophage polarization from the inflammatory M1 phenotype to the tissue regenerative M2 phenotype and resulting in functional recovery of neurons. In a rat sciatic nerve crush model, NGC promoted remyelination and functional and structural regeneration. Generally, the DMF/RSF/P:P conduit provides a new potential therapeutic approach to promote nerve repair in future clinical treatments.

Biomimetic Structural Protein Based Magnetic Responsive Scaffold for Enhancing Bone Regeneration by Physical Stimulation on Intracellular Calcium Homeostasis

The bone matrix has distinct architecture and biochemistry which present a barrier to synthesizing bone-mimetic regenerative scaffolds. To mimic the natural structures and components of bone, biomimetic structural decellularized extracellular matrix (ECM)/regenerated silk fibroin (RSF) scaffolds incorporated with magnetic nanoparticles (MNP) are prepared using a facile synthetic methodology. The ECM/RSF/MNP scaffold is a hierarchically organized and interconnected porous structure with silk fibroin twined on the collagen nanofibers. The scaffold demonstrates saturation magnetization due to the presence of MNP, along with good cytocompatibility. Moreover, the β-sheet crystalline domain of RSF and the chelated MNP could mimic the deposition of hydroxyapatite and enhance compressive modulus of the scaffold by ≈20%. The results indicate that an external static magnetic field (SMF) with a magnetic responsive scaffold effectively promotes cell migration, osteogenic differentiation, neogenesis of endotheliocytes in vitro, and new bone formation in a critical-size femur defect rat model. RNA sequencing reveals that the molecular mechanisms underlying this osteogenic effect involve calsequestrin-2-mediated Ca2+ release from the endoplasmic reticulum to activate Ca2+ /calmodulin/calmodulin-dependent kinase II signaling axis. Collectively, bionic magnetic scaffolds with SMF stimulation provide a potent strategy for bone regeneration through internal structural cues, biochemical composition, and external physical stimulation on intracellular Ca2+ homeostasis.

[Analysis of management efficacy in patients with heavy menstrual bleeding associated with antithrombotic therapy]

Objective: To evaluate different methods' efficacy of controlling acute bleeding and managing long-term menstruation in patients with heavy menstrual bleeding (HMB) associated with antithrombotic therapy. Methods: The clinical data of 22 cases with HMB associated with antithrombotic therapy admitted to Peking University People's Hospital from January 2010 to August 2022 were analyzed, aged 39 years old (26-46 years). Changes in menstrual volume, hemoglobin (Hb), and quality of life were collected after control of acute bleeding and long-term menstrual management. Menstrual volume was assessed by pictorial blood assessment chart (PBAC), and quality of life was assessed by menorrhagia multi-attribute scale (MMAS). Results: (1) Treatment of acute bleeding: of the 22 cases with HMB associated with antithrombotic therapy, 16 cases were treated in our hospital and 6 in other hospital for emergency bleeding; of the 16 cases treated in our hospital, 3 underwent emergency intrauterine Foley catheter balloon compression due to severe bleeding (Hb decreased by 20 to 40 g/L within 12 hours). Of the 22 cases with antithrombotic therapy-related HMB, 15 (including 2 cases with severe bleeding) underwent emergency aspiration or endometrial resection, and intraoperative placement of levonorgestrel-releasing intrauterine system (LNG-IUS) followed by a significant reduction in bleeding volume; 3 cases had controlled acute bleeding after rivaroxaban dose reduction and continued observation; 2 cases were given gonadotropin-releasing hormone agonists to control acute bleeding in other hospital, of which 1 case was temporarily treated with periodic blood transfusion, and the other one patient underwent total hysterectomy; and 2 cases had temporary amenorrhea with oral mifepristone after intrauterine balloon compression or oral norethindrone. (2) Long-term menstrual management: of the 22 cases with antithrombotic therapy-related HMB, 15 had LNG-IUS placement and 12 had LNG-IUS placement for 6 months, and menstrual volume was significantly reduced [PBAC scores were 365.0 (272.5-460.0) vs 25.0 (12.5-37.5), respectively; Z=4.593, P<0.001], Hb was significantly increased [91.5 g/L (71.8-108.2 g/L) vs 128.5 g/L (121.2-142.5 g/L); Z=4.695, P<0.001], and quality of life was significantly improved [MMAS scores were 415.0 (327.5-472.5) vs 580.0 (570.0-580.0), respectively; Z=-3.062, P=0.002] before placement compared with 6 months after placement. Three rivaroxaban dose reduction patients' PBAC scores decreased by 20 to 35 but remained >100, and perceived quality of life did not change significantly. Two cases with temporary amenorrhea treated with oral mifepristone felt significantly improved quality of life, and the MMAS scores increased by 220 and 180, respectively. Conclusion: Intrauterine Foley catheter balloon compression, aspiration or endometrial ablation could be used to control acute bleeding in patients with antithrombotic therapy-related HMB, and LNG-IUS for long-term management could reduce menstrual volume, increase hemoglobin, and improve the quality of life of patients.

Piezoresistive MXene/Silk fibroin nanocomposite hydrogel for accelerating bone regeneration by Re-establishing electrical microenvironment

The electrical microenvironment plays an important role in bone repair. However, the underlying mechanism by which electrical stimulation (ES) promotes bone regeneration remains unclear, limiting the design of bone microenvironment–specific electroactive materials. Herein, by simple co-incubation in aqueous suspensions at physiological temperatures, biocompatible regenerated silk fibroin (RSF) is found to assemble into nanofibrils with a β-sheet structure on MXene nanosheets, which has been reported to inhibit the restacking and oxidation of MXene. An electroactive hydrogel based on RSF and bioencapsulated MXene is thus prepared to promote efficient bone regeneration. This MXene/RSF hydrogel also acts as a piezoresistive pressure transducer, which can potentially be utilized to monitor the electrophysiological microenvironment. RNA sequencing is performed to explore the underlying mechanisms, which can activate Ca²⁺/CALM signaling in favor of the direct osteogenesis process. ES is found to facilitate indirect osteogenesis by promoting the polarization of M2 macrophages, as well as stimulating the neogenesis and migration of endotheliocytes. Consistent improvements in bone regeneration and angiogenesis are observed with MXene/RSF hydrogels under ES in vivo. Collectively, the MXene/RSF hydrogel provides a distinctive and promising strategy for promoting direct osteogenesis, regulating immune microenvironment and neovascularization under ES, leading to re-establish electrical microenvironment for bone regeneration.

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MXene nanosheets could direct the selective growth of silk nanofibrils.

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Prepared MXene/RSF hydrogel exhibited good conductivity and sensing ability.

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The electroactive hydrogel could promote osteogenic differentiation of BMSCs by activating the Ca²⁺/CALM signaling pathway.

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The conductive system created an osteoblast–macrophage–endotheliocyte virtuous circle for bone microenvironment.

Injectable Mussel-Inspired highly adhesive hydrogel with exosomes for endogenous cell recruitment and cartilage defect regeneration

In the early stage of osteoarthritis (OA), cartilage degradation in the surface region leads to superficial cartilage defect. However, enhancing the regeneration of cartilage defect remains a great challenge for existing hydrogel technology because of the weak adhesion to wet tissue. In the present study, an injectable mussel-inspired highly adhesive hydrogel with exosomes was investigated for endogenous cell recruitment and cartilage defect regeneration. The hydrogel with high bonding strength to the wet surface was prepared using a crosslinked network of alginate-dopamine, chondroitin sulfate, and regenerated silk fibroin (AD/CS/RSF). Compared with commercial enbucrilate tissue adhesive, the AD/CS/RSF hydrogel provided a comparative lap shear strength of 120 kPa, with a similar gelation time and a higher capacity for maintaining adhesive strength. The AD/CS/RSF/EXO hydrogel with encapsulated exosomes recruited BMSCs migration and inflation, promoted BMSCs proliferation and differentiation. Most importantly, the AD/CS/RSF/EXO hydrogel accelerated cartilage defect regeneration in situ, and extracellular matrix remodeling after injection in rat patellar grooves. The exosomes released by the hydrogels could recruit BMSCs into the hydrogel and neo-cartilage via the chemokine signaling pathway. Our findings reveal an injectable and adhesive hydrogel for superficial cartilage regeneration, which is a promising approach for minimally treating cartilage defect with arthroscopic assistance.

[Analysis of pathogen spectrum and antimicrobial resistance of pathogens associated with hospital-acquired infections collected from 11 teaching hospitals in 2018]

Objective: To investigate the spectrum and antimicrobial resistance of major pathogens causing nosocomial infections in China, 2018. Methods: Non-duplicated nosocomial cases as well as pathogens causing bloodstream infections (BSI), hospital-acquired pneumonia (HAP) and intra-abdominal infections (IAI) from 11 teaching hospitals across China were collected. The minimum inhibitory concentrations (MICs) of clinically significant strains were determined by agar dilution method or broth microdilution method. The Clinical and Laboratory Standards Institute (CLSI) M100-S29 criteria were used for interpretation, and the WHONET-5.6 software was used in data analysis. Results: A total of 1 590 cases were collected, including 831 cases from BSI, 450 cases from HAP and 309 cases from IAI. The most prevalent pathogens causing BSI were Escherichia coli (29.2%, 243/831), Klebsiella pneumoniae (16.2%, 135/831) and Staphylococcus aureus (10.1%, 84/831); the most prevalent pathogens causing IAI were E. coli (26.2%, 81/309), Enterococcus faecium (15.5%, 48/309) and K. pneumoniae (13.3%, 41/309); while Acinetobacter baumanii (24.7%, 111/450), Pseudomonas aeruginosa (20.7%, 93/450) and K. pneumoniae (16.2%, 73/450) were dominated in HAP. All S. aureus were susceptible to tigecycline, linezolid, daptomycin and glycopeptides; 77.8% (105/135) of S. aureus strains were susceptible to ceftaroline. Methicillin-resistant S. aureus (MRSA) accounted for 29.6% (40/135) of all the S. aureus, and was lower than the accounted rate of methicillin-resistant coagulase-negative Staphylococcus (MRCNS) (83.7%, 41/49). One E. faecium strain (1.1%, 1/95) resistant to vacomycin and teicoplanin and one E. faecalis strain (2.3%, 1/43) resistant to linezolid was found. The prevalence of extended-spectrum β-lactamase (ESBL) was 56.1% (193/344) in E. coli and 22.1% (55/249) in K. pneumonia; the rate of carbapenem resistant E. coli and K. pneumonia was 4.1% (14/344) and 22.9% (57/249), respectively; the percentage of ceftazidime/avibactam resistant E. coli and K. pneumonia was 2.3% (8/344) and 2.0% (5/249), respectively; the percentage of colistin resistant E. coli and K. pneumonia was 1.5% (5/344) and 7.6% (19/249), respectively; no E. coli and K. pneumonia strains were found resistant to tigecycline. The rate of carbapenem resistant A. baumanii and P. aeruginosa were 78.9% (146/185) and 36.7% (66/180), respectively. A. baumanii showed low susceptibility to the antimicrobial agents except colistin (99.5%, 184/185) and tigecycline (91.4%, 169/185). Colistin, amikacin and ceftazidime/avibactam demonstrated high antibacterial activity against P. aeruginosa with susceptility rate of 100% (180/180), 93.3% (168/180) and 85.6% (154/180), respectively. Conclusions: Nosocomial Gram-negative pathogens show high susceptibilities to tigecycline, colistin and ceftazidime/avibactam in vitro. Antimicrobial resistance in A. baumannii is a serious problem. The prevalence of carbapenem-resistant Enterobacteriaceae has increased, which should be monitored continuously in China.

Virulence and potential pathogenicity of coccoid Helicobacter pylori induced by antibiotics

AIM: To explore the virulence and the potential pathogenicity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to antibiotic.

METHODS: Three strains of H. pylori, isolated from gastric biopsy specimens of confirmed peptic ulcer, were converted from spiral into coccoid from by exposure to metronidazole. Both spiral and coccoid form of H. pylori were tested for the urease activity, the adherence to Hep 2 cells and the vacuolating cytotoxicity to Hela cells, and the differences of the protein were analysed by SDS-PAGE and Western blot. The mutation of the genes including ureA, ureB, hpaA, vacA and cagA, related with virulence, was detected by means of PCR and PCR-SSCP.

RESULTS: In the coccoid H. pylori, the urease activity, the adherence to Hep 2 cells and the vacuolating cytotoxicity to Hela cells alldecreased. In strain F₄₄, the rate and index of adherence reduced from 70.0% ± 5.3% to 33% ± 5.1% and from 2.6 ± 0.4 to 0.96 ± 0.3 (P < 0. 01), respectively. The invasion of coccoid H. pylori into Hep 2 cell could be seen under electronmicroscope. SDS-PAGE showed that the content of the protein with the molecular weight over Mr 74000 decreased, and the hybriditional signal in band Mr 125000 weakened, while the band M_r 110000 and Mr 63000 strengthened in coccoid H.pylori as shown in Western blot. The results of PCR were all positive, and PCR-SSCP indicated that there may exist the point mutation in gene hpaA or vacA.

CONCLUSION: The virulence and the proteins with molecular weight over Mr 74000 in coccoid H.pylori decrease, but no deletion exists in amplification fragments from ureA, ureB, hpaA, vacA and cagA genes, suggesting that coccoid H.pylori may have potential pathogenicity.

Diabetic retinopathy and serum lipids

The association between serum lipid levels and diabetic retinopathy has been investigated in many studies. Some studies show a positive relationship between serum cholesterol and low-density lipoprotein levels and retinal hard exudation. Other studies show serum triglyceride levels as being important in the progression of retinopathy. Certain other studies show no relationship between serum lipid levels and diabetic retinopathy. We review the literature on this subject and illustrate this report with an example of a diabetic with severe diabetic maculopathy and high serum lipid levels.

Results of revision total knee arthroplasty

BACKGROUND/AIM OF STUDY

The results of primary total knee arthroplasties have improved over the years but some still fail, requiring revision. Revision total knee arthroplasty is technically more difficult and has not enjoyed the same success rates as the index operation. The aim of this retrospective study was to review the results of revision total knee arthroplasties carried out at our centre. This is the first study in Singapore on revision total knee arthroplasty.

METHODS

A retrospective study where 17 patients (18 knees) had been followed up since their revision operations were clinically assessed. Based on the Knee Society Clinical Scoring System, they were assigned separate knee and function scores (each having a maximum possible 100).

RESULTS

The mean knee score was 76 (range 35-93), which rates as good. Of the 18 knees, 67% had excellent or good knee scores. By comparison, the mean function score was 56 (range 0-90) which rates as poor and 33% had excellent or good function scores.

CONCLUSION

Revision total knee arthroplasty achieves good and excellent results in spite of technical difficulties often associated with the revision operation. The difference in mean knee and function scores emphasises that many other factors such as physical strength and stamina affect function. Nevertheless, 15 patients were able to walk out of their house and around their neighbourhood for varying distances. This satisfied their expectations and the poor mean function score may reflect different expectations of patients overseas from whence this scoring system originated.

Screening for hypercholesterolaemia in patients with other risk factors for coronary heart disease

OBJECTIVE

To determine the prevalence of hypercholesterolaemia in individuals with other major risk factors of coronary heart disease and markers of hypercholesterolaemia.

METHODS

A community-based cross-sectional study on a random sample of 261 persons aged between 35 and 69 years residing in the flatted housing estate of West Coast, Singapore, was conducted in 1997. A questionnaire, together with a medical examination and investigation involving the use of Reflotron machine, were used to collect the information required.

RESULTS

43.2% of the population had at least 1 major risk factor, with 18.1% being smokers, 18.1% with hypertension, 6.5% with diabetes mellitus, 5.1% being obese, and 5.0% with a family history of coronary heart disease. Higher percentages of individuals with hypercholesterolaemia were found when each risk factor was present. 9.5% had 2 or more risk factors, of which, 21.1% had high cholesterol levels. A high prevalence of hypercholesterolaemia that was statistically significant was found amongst subjects with corneal arcus below the age of 60.

CONCLUSIONS

The risk factors of coronary heart disease remain prevalent in our population. We recommend screening for serum cholesterol only in those with at least 2 major risk factors of coronary heart disease in the general population between 35 and 69 years of age.

Intestinal epithelia (T84) possess basolateral ligands for CD11b/CD18-mediated neutrophil adherence

The process of active intestinal inflammation can be modeled by the migration of neutrophils [polymorphonuclear leukocytes (PMN)] across monolayers of the human intestinal cell line T84. We now evaluate the polarity of early adhesive events occurring between human PMN and ligands on intact T84 monolayers. Transient Ca2+ depletion (tr-Ca-depl) of confluent monolayers grown on permeable supports (2 mM EDTA, 12 min, 37 degrees C) resulted in disruption of tight junctions separating apical and basolateral domains (resistance fell from 973 +/- 35 to 57.4 +/- 3.8 omega.cm2 after 12 min). The columnar T84 phenotype was not grossly altered by tr-Ca-depl. Access to basolateral membrane proteins from the apical surface after tr-Ca-depl was confirmed by enzyme-linked immunosorbant assay and immunofluorescence, using antibodies to the basolateral proteins E-Cadherin and beta 1-integrin. The effects of tr-Ca-depl on early events in PMN adhesion were next assessed. Neutrophils (2 x 10(6)) were applied to the apical surface of monolayers followed by stimulation with the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (100 nM, 5 min, 37 degrees C) and quantitation. In comparison with control monolayers, tr-Ca-depl increased subsequent PMN adhesion (1.7 +/- 0.24 vs. 3.1 +/- 0.28 x 10(4) adherent PMN/monolayer; P < 0.005), which was inhibited 80% by anti-CD11b/CD18 antibodies. These experiments suggest that PMN adhere to subjunctional ligands on T84 cells in a CD11b/CD18-dependent fashion.