BACKGROUND: Systemic administrations are widely used in preventing or curing bone infections, however, it accompanied by great adverse reactions and limited local blood drug levels. Therefore, local administration becomes a research focus, which aimed to explore a carrier possess good biocompatibility and slow-release antibiotics. OBJECTIVE: To explore the effect of calcium alginate gel compound vancomycin on prevention of bone infection, simultaneously, single drug was injected or implanted into models to compare the results.METHODS: A total of 60 healthy adult New Zealand white rabbits were prepared for osteomyelitis models by injecting Staphylococcus auraus to right tibiae medullaris, and randomly divided into systemic treatment, tricalcium phosphate and calcium alginate gel groups. After model preparation, rabbits in the systemic treatment group were intramuscular injected vancomycin (0.03 g, twice per day, for 4 successive days); in the triceicium phosphate group, 1 g tricalcium phosphate combined with 0.1 g vancomycin.was filled in the defects, sealed with bone wax. In the calcium alginate gel group, calcium alginate gel combined with vancomycin was implanted. Gross observation, radiological image and histological analysis were performed at weeks 4 and 8 after operation.RESULTS AND CONCLUSION: Local swelling and partial sinus were found in the systemic treatment and tricalcium phosphate groups after operation. The pathological slice showed that there were a large number of lymphocytes and some sequestrum in the systemic treatment and tricelcium phosphate groups. However, there was no manifestation of osteomyelitis in the calcium alginate gel group. The results suggested that calcium alginate gel compound vancomycin exhibit superior therapeutic effect on prevention of bone infection to local administration of calcium alginate gel combined with vancomycin or systemic application of vancomycin.

OBJECTIVETo detect the expression of cytokines by acute promyelocytic leukemia (APL) cells before and after exposure to arsenic trioxide.

METHODSDiagnoses were performed according to the FAB cytological classification criteria and cytogenetic criteria. Bone marrow or blood samples from APL patients were collected in heparinized tubes, then primary APL cells were separated by traditional Ficoll-Hypaque density centrifugation and purified after adherence to plastic surfaces. IL-1(beta), IL-6, IL-8, TNF alpha and G-CSF levels in the leukemia cell culture supernatants were detected by ELISA. At the same time, nitro blue tetrazolium (NBT) reduction test was used to detect the differentiation of APL cells.

RESULTSAfter 96 hours exposure to arsenic trioxide, 10 - 6 mol/L in vitro or 10 mg/d in vivo, APL cells showed a significant increase of IL-1(beta) (P < 0.05) and G-CSF (P < 0.05) production, and a significant decrease of IL-6 (P < 0.05) and IL-8 (P < 0.05). However, there was no obvious variation of TNF alpha when compared with APL cells without exposure to arsenic trioxide. On the other hand, the proliferation ratio of APL cells in vitro was statistically correlated to the IL-1(beta) secretion ratio or G-CSF secretion ratio. The cell number ratio in patients with detectable IL-1(beta) or G-CSF was higher than that without detectable IL-1(beta) or G-CSF.

CONCLUSIONIL-1(beta) and G-CSF secretion may play an important role in the proliferation of APL cells after exposure to arsenic trioxide.

Arsenicals ; pharmacology ; Cells, Cultured ; Cytokines ; secretion ; Granulocyte Colony-Stimulating Factor ; secretion ; Humans ; Interleukin-1 ; secretion ; Interleukin-6 ; secretion ; Interleukin-8 ; secretion ; Leukemia, Promyelocytic, Acute ; metabolism ; Oxides ; pharmacology ; Tumor Necrosis Factor-alpha ; secretion

BACKGROUNDInjectable three-dimensional (3D) scaffolds have the advantages of fluidity and moldability to fill irregular-shaped defects, simple incorporation of bioactive factors, and limited surgical invasiveness. Adipose-derived stem cells (ADSCs) are multipotent and can be differentiated toward nucleus pulposus (NP)-like cells. A hypoxic environment may be important for differentiation to NP-like cells because the intervertebral disc is an avascular tissue. Hence, we investigated the induction effects of hypoxia and an injectable 3D chitosan-alginate (C/A) gel scaffold on ADSCs.

METHODSThe C/A gel scaffold consisted of medical-grade chitosan and alginate. Gel porosity was calculated by liquid displacement method. Pore microstructure was analyzed by light and scanning electron microscopy. ADSCs were isolated and cultured by conventional methods. Passage 2 BrdU-labeled ADSCs were co-cultured with the C/A gel. ADSCs were divided into three groups (control, normoxia-induced, and hypoxia-induced groups). In the control group, cells were cultured in 10% FBS/DMEM. Hypoxia-induced and normoxia-induced groups were induced by adding transforming growth factor-β1, dexamethasone, vitamin C, sodium pyruvate, proline, bone morphogenetic protein-7, and 1% ITS-plus to the culture medium and maintaining in 2% and 20% O2, respectively. Histological and morphological changes were observed by light and electron microscopy. ADSCs were characterized by flow cytometry. Cell viability was investigated by BrdU incorporation. Proteoglycan and type II collagen were measured by safranin O staining and the Sircol method, respectively. mRNA expression of hypoxia-inducing factor-1α (HIF-1α), aggrecan, and Type II collagen was determined by reverse transcription-polymerase chain reaction.

RESULTSC/A gels had porous exterior surfaces with 80.57% porosity and 50-200 üm pore size. Flow cytometric analysis of passage 2 rabbit ADSCs showed high CD90 expression, while CD45 expression was very low. The morphology of induced ADSCs resembled that of NP cells. BrdU immunofluorescence showed that most ADSCs survived and proliferated in the C/A gel scaffold. Scanning electron microscopy showed that ADSCs grew well in the C/A gel scaffold. ADSCs in the C/A gel scaffold were positive for safranin O staining. Hypoxia-induced and normoxia-induced groups produced more proteoglycan and Type II collagen than the control group (P < 0.05). Proteoglycan and Type II collagen levels in the hypoxia-induced group were higher than those in the normoxia-induced group (P < 0.05). Compared with the control group, higher mRNA expression of HIF-1α, aggrecan, and Type II collagen was detected in hypoxia-induced and normoxiainduced groups (P < 0.05). Expression of these genes in the hypoxia-induced group was significantly higher than that in the normoxia-induced group (P < 0.05).

CONCLUSIONADSCs grow well in C/A gel scaffolds and differentiate toward NP-like cells that produce the same extracellular matrix as that of NP cells under certain induction conditions, which is promoted in a hypoxic state.

Adipose Tissue ; cytology ; Alginates ; chemistry ; Animals ; Cell Differentiation ; physiology ; Cells, Cultured ; Chitosan ; chemistry ; Glucuronic Acid ; chemistry ; Hexuronic Acids ; chemistry ; Rabbits ; Stem Cells ; cytology ; physiology ; Tissue Engineering ; methods ; Tissue Scaffolds ; chemistry

Objective:To report the results of national surveillance on the distribution and antimicrobial resistance profile of clinical Gram-negative bacteria isolates from bloodstream infections in China in 2022.Methods:The clinical isolates of Gram-negative bacteria from blood cultures in member hospitals of national bloodstream infection Bacterial Resistant Investigation Collaborative System（BRICS）were collected during January 2022 to December 2022. Antibiotic susceptibility tests were conducted by agar dilution or broth dilution methods recommended by Clinical and Laboratory Standards Institute（CLSI）. WHONET 5.6 and SPSS 25.0 software were used to analyze the data.Results:During the study period，9 035 strains of Gram-negative bacteria were collected from 51 hospitals，of which 7 895（87.4%）were Enterobacteriaceae and 1 140（12.6%）were non-fermenting bacteria. The top 5 bacterial species were Escherichia coli（ n=4 510，49.9%）， Klebsiella pneumoniae（ n=2 340，25.9%）， Pseudomonas aeruginosa（ n=534，5.9%）， Acinetobacter baumannii complex（ n=405，4.5%）and Enterobacter cloacae（ n=327，3.6%）. The ESBLs-producing rates in Escherichia coli， Klebsiella pneumoniae and Proteus spp. were 47.1%（2 095/4 452），21.0%（427/2 033）and 41.1%（58/141），respectively. The prevalence of carbapenem-resistant Escherichia coli（CREC）and carbapenem-resistant Klebsiella pneumoniae（CRKP）were 1.3%（58/4 510）and 13.1%（307/2 340）；62.1%（36/58）and 9.8%（30/307）of CREC and CRKP were resistant to ceftazidime/avibactam combination，respectively. The prevalence of carbapenem-resistant Acinetobacter baumannii（CRAB）complex was 59.5%（241/405），while less than 5% of Acinetobacter baumannii complex was resistant to tigecycline and polymyxin B. The prevalence of carbapenem-resistant Pseudomonas aeruginosa（CRPA）was 18.4%（98/534）. There were differences in the composition ratio of Gram-negative bacteria in bloodstream infections and the prevalence of main Gram-negative bacteria resistance among different regions，with statistically significant differences in the prevalence of CRKP and CRPA（ χ2=20.489 and 20.252， P<0.001）. The prevalence of CREC，CRKP，CRPA，CRAB，ESBLs-producing Escherichia coli and Klebsiella pneumoniae were higher in provinicial hospitals than those in municipal hospitals（ χ2=11.953，81.183，10.404，5.915，12.415 and 6.459， P<0.01 or <0.05），while the prevalence of CRPA was higher in economically developed regions（per capita GDP ≥ 92 059 Yuan）than that in economically less-developed regions（per capita GDP <92 059 Yuan）（ χ2=6.240， P=0.012）. Conclusions:The proportion of Gram-negative bacteria in bloodstream infections shows an increasing trend，and Escherichia coli is ranked in the top，while the trend of CRKP decreases continuously with time. Decreasing trends are noted in ESBLs-producing Escherichia coli and Klebsiella pneumoniae. Low prevalence of carbapenem resistance in Escherichia coli and high prevalence in CRAB complex have been observed. The composition ratio and antibacterial spectrum of bloodstream infections in different regions of China are slightly different，and the proportion of main drug resistant bacteria in provincial hospitals is higher than those in municipal hospitals.