Is it safe and effective to extract impacted maxillary tooth adjacent to maxillary sinus via submaxillary sinus membrane space approach?-a randomized controlled trial.

OBJECTIVE: To evaluate the clinical outcomes following extraction of impacted maxillary tooth adjacent to maxillary via submaxillary sinus membrane space approach. MATERIALS AND METHODS: Seventy-two patients were enrolled in our study. The positions of the maxillary impacted tooth were confirmed by cone-beam computed tomography (CBCT). Cases were randomly divided into two groups: the "submaxillary sinus membrane space approach" was applied in the new method (NM) group, and the conventional "avoid maxillary sinus membrane exposure" strategy was executed in the traditional method (TM) group. The clinical and follow-up data were recorded. RESULTS: The duration of the procedure in the TM group was significantly longer than those in the NM group (P < 0.05). Four teeth were accidentally displaced into the maxillary sinus with MSM perforation. The MSM perforation rate was slightly higher in the TM group than in the NM group, however, without significant difference between the two groups (8/36 vs. 3/36, P = 0.19). The maxillary sinus membrane perforation was associated with the displacement of tooth into the maxillary sinus (OR = 16.2, P = 0.026). The root tip exposure of the adjacent tooth was significantly higher in the TM group than in the NM group (10/36 vs. 1/36, P = 0.006). The incidence of reduced pulp vitality of the adjacent tooth was significantly higher in the TM group (10/36 vs. 1/36, P = 0.006), and it was associated with the exposure of the root tip intraoperatively (OR = 456.5, P < 0.001). The incidence of external root resorption was significantly lower in the NM group, and there was no significant association with the root exposure intraoperatively (OR = 3.7, P = 0.47). CONCLUSIONS: Submaxillary sinus membrane space approach is a safe and efficient approach in extraction of impacted maxillary tooth. It is an alternative way for cases which are in close proximity to the maxillary sinus. CLINICAL RELEVANCE: A novel method to extract impacted maxillary tooth adjacent to maxillary sinus.

Fermentation of NaHCO3-treated corn germ meal by Bacillus velezensis CL-4 promotes lignocellulose degradation and nutrient utilization.

Sodium bicarbonate pretreatment and solid-state fermentation (SSF) were used to maximize the nutritional value of corn germ meal (CGM) by inoculating it with Bacillus velezensis CL-4 (isolated from chicken cecal contents and capable of degrading lignocellulose). Based on genome sequencing, B. velezensis CL-4 has a 4,063,558 bp ring chromosome and 46.27% GC content. Furthermore, genes associated with degradation of lignocellulose degradation were detected. Pretreatment of CGM (PCGM) with sodium bicarbonate (optimized to 0.06 g/mL) neutralized low pH. Fermented and pretreated CGM (FPCGM) contained more crude protein (CP), soluble protein of trichloroacetic acid (TCA-SP), and total amino acids (aa) than CGM and PCGM. Degradation rates of cellulose and hemicellulose were reduced by 21.33 and 71.35%, respectively, after 48 h fermentation. Based on electron microscopy, FPCGM destroys the surface structure and adds small debris of the CGM substrate, due to lignocellulose breakdown. Furthermore, 2-oxoadipic acid and dimethyl sulfone were the most important metabolites during pretreatment. Concentrations of adenosine, cytidine, guanosine, S-methyl-5'-thioadenosine, and adenine decreased significantly after 48 h fermentation, whereas concentrations of probiotics, enzymes, and fatty acids (including palmitic, 16-hydroxypalmitic, and linoleic acids) were significantly improved after fermentation. In conclusion, the novel pretreatment of CGM provided a proof of concept for using B. velezensis CL-4 to degrade lignocellulose components, improve nutritional characteristics of CGM, and expand CGM lignocellulosic biological feed production. KEY POINTS: • Sodium bicarbonate (baking soda) can be used as an economical and green additive to pretreat corn germ meal; • Fermentation with B. velezensis degrades the cellulose and hemicellulose component of corn germ meal and improves its feed quality; • As a novel qualified presumption of safety (QPS) strain, B. velezensis should have broad potential applications in food and feed industries.

[Efficacy Evaluation of Three Endoscopic Therapies of Isolated Gastric Varices with Modified Tissue Adhesive].

Objective: To evaluate the efficacy of three endoscopic therapies of isolated gastric varices (IGV) with modified tissue adhesive. Methods: A retrospective analysis was conducted with the clinical data of 73 IGV patients who were treated between January 2008 and December 2019 at Beijing Ditan Hospital. Patient clinical data on age, sex, etiology, biochemistry findings, Child-Pugh classification, the type of spontaneous shunt, preoperative bleeding history, and the presence or absence of liver cancer were collected. The three therapies evaluated were endoscopic intravenous injection of tissue glue combined with lauromacrogol, endoscopic clip-assisted intravenous injection of tissue glue combined with lauromacrogol, and endoscopic clip and LOOP-assisted intravenous injection of tissue glue combined with lauromacrogol. Their respective clinical treatment outcomes, including ectopic embolism rate, survival rate, rebleeding rate, amount of lauromacrogol and tissue glue used, the number of endoscopic clips used, and the number of times of the procedure the patient underwent, were evaluated. Results: In the patient baseline data, Child-Pugh grade, preoperative thrombus formation, and the presence or absence of liver cancer, showed significant difference between the three therapies ( P<0.05). There was no significant difference in the rates of ectopic embolism among the three methods ( P>0.05), but no ectopic embolism occurred after endoscopic clip-assisted intravenous injection of tissue glue combined with lauromacrogol, or after endoscopic clip and LOOP-assisted intravenous injection of tissue glue combined with lauromacrogol. There was no significant difference in the survival rate, the rebleeding rate, amount of lauromacrogol and tissue glue used for the three therapies, but there was significant difference in the number of endoscopic clips used and the number of times the procedure was conducted within one year ( P<0.05). Conclusion: The two endoscopic therapies of intravenous injection of modified tissue glue, one assisted by clip and the other assisted by clip and LOOP, can help reduce the number of procedures IGV patients undergo within one year.

An improved and efficient method of Agrobacterium syringe infiltration for transient transformation and its application in the elucidation of gene function in poplar.

BACKGROUND: Forest trees have important economic and ecological value. As a model tree, poplar has played a significant role in elucidating the molecular mechanisms underlying tree biology. However, a lack of mutant libraries and time-consuming stable genetic transformation processes severely limit progress into the functional characterization of poplar genes. A convenient and fast transient transformation method is therefore needed to enhance progress on functional genomics in poplar. METHODS: A total of 11 poplar clones were screened for amenability to syringe infiltration. Syringe infiltration was performed on the lower side of the leaves of young soil-grown plants. Transient expression was evaluated by visualizing the reporters ß-glucuronidase (GUS) and green fluorescent protein (GFP). The experimental parameters of the syringe agroinfiltration were optimized based on the expression levels of the reporter luciferase (LUC). Stably transformed plants were regenerated from transiently transformed leaf explants through callus-induced organogenesis. The functions of Populus genes in secondary cell wall-thickening were characterized by visualizing lignin deposition therein after staining with basic fuchsin. RESULTS: We greatly improved the transient transformation efficiency of syringe Agrobacterium infiltration in poplar through screening for a suitable poplar clone from a variety of clones and optimizing the syringe infiltration procedure. The selected poplar clone, Populus davidiana × P. bolleana, is amenable to Agrobacterium syringe infiltration, as indicated by the easy diffusion of the bacterial suspension inside the leaf tissues. Using this technique, we localized a variety of poplar proteins in specific intracellular organelles and illustrated the protein-protein and protein-DNA interactions. The transiently transformed leaves could be used to generate stably transformed plants with high efficiency through callus induction and differentiation processes. Furthermore, transdifferentiation of the protoxylem-like vessel element and ectopic secondary wall thickening were induced in the agroinfiltrated leaves via the transient overexpression of genes associated with secondary wall formation. CONCLUSIONS: The application of P. davidiana × P. bolleana in Agrobacterium syringe infiltration provides a foundation for the rapid and high-throughput functional characterization of Populus genes in intact poplar plants, including those involved in wood formation, and provides an effective alternative to Populus stable genetic transformation.

[Influence of Meteorological Factors on HFMD and Construction of Prediction Model in Sichuan Province].

OBJECTIVE: To analyze the epidemiological characteristics of hand, foot and mouth disease (HFMD) in Sichuan Province from 2013 to 2019. To study the correlation between meteorological factors and the incidence of HFMD and construct a prediction model. METHODS: The HMFD surveillance data and meteorological data from 2013 to 2019 in Sichuan Province were collected through the Chinese Center for Disease Control and Prevention and the China Meteorological data Network. Spearman correlation was used to analyze the relationship between HFMD incidence and meteorological factors. Multiple regression model and support vector regression (SVR) model were used to construct HFMD incidence prediction models respectively. RESULTS: A total of 615 840 cases of HFMD and 81 deaths were reported from 2013 to 2019. The average annual incidence rate was 107.31/105, and the mortality rate was 0.16/106. Spearman correlation analysis showed that the monthly incidence rate of HFMD was correlated with monthly average relative humidity (r=0.342), monthly average temperature (r=0.284), monthly average water vapor pressure (r=0.304) and monthly average days of precipitation (r=0.259). The prediction effect of the SVR model (R2=0.836) was better than the multiple regression model (R2=0.375). The SVR model provided a good fit to the monthly incidence of HFMD from 2013 to 2018, and can predict the peak incidence of HFMD in 2019. CONCLUSION: Relative humidity has the greatest influence on the incidence of HFMD. The fitting value of SVR model is in good agreement with the actual value, which is valuable in predicting the incidence of HFMD in Sichuan Province.

Endoplasmic reticulum-localized UBC34 interaction with lignin repressors MYB221 and MYB156 regulates the transactivity of the transcription factors in Populus tomentosa.

BACKGROUND: Regulation of lignin biosynthesis is known to occur at the level of transcription factors (TFs), of which R2R3-MYB family members have been proposed to play a central role via the AC cis-elements. Despite the important roles of TFs in lignin biosynthesis, the post-translational regulation of these TFs, particularly their ubiquitination regulation, has not been thoroughly explored. RESULTS: We describe the discovery of a Populus tomentosa E2 ubiquitin-conjugating enzyme 34 (PtoUBC34), which is involved in the post-translational regulation of transactivation activity of lignin-associated transcriptional repressors PtoMYB221 and PtoMYB156. PtoUBC34 is localized at the endoplasmic reticulum (ER) membrane where it interacts with transcriptional repressors PtoMYB221 and PtoMYB156. This specific interaction allows for the translocation of TFs PtoMYB221 and PtoMYB156 to the ER and reduces their repression activity in a PtoUBC34 abundance-dependent manner. By taking a molecular biology approach with quantitative real-time polymerase chain reaction (qRT-PCR) analysis, we found that PtoUBC34 is expressed in all aboveground tissues of trees in P. tomentosa, and in particular, it is ubiquitous in all distinct differentiation stages across wood formation, including phloem differentiation, cambium maintaining, early and developing xylem differentiation, secondary cell wall thickening, and programmed cell death. Additionally, we discovered that PtoUBC34 is induced by treatment with sodium chloride and heat shock. CONCLUSIONS: Our data suggest a possible mechanism by which lignin biosynthesis is regulated by ER-localized PtoUBC34 in poplar, probably through the ER-associated degradation (ERAD) of lignin-associated repressors PtoMYB221 and PtoMYB156.

IOP measurement in silicone oil tamponade eyes by Corvis ST tonometer, Goldmann applanation tonometry and non-contact tonometry.

PURPOSE: To compare the postoperative intraocular pressure (IOP) of eyes following pars plana vitrectomy (PPV) combined with intravitreal silicone oil (SO) tamponade by Corneal Visualization Scheimpflug Technology (CST), Goldmann applanation tonometry (GAT) and non-contact tonometry (NCT). METHODS: Thirty-eight participants who had undergone PPV combined with SO tamponade to treat vitreoretinal diseases were enrolled. Postoperative IOP measurements were obtained using CST, NCT and GAT. Inter-device agreement was assessed by Bland-Altman analysis. The correlation coefficient was used to describe the potential postoperative factors affecting the postoperative IOP differences between each device. RESULTS: Bland-Altman analysis revealed the bias between CST and GAT, between CST and NCT, and between GAT and NCT to be -0.2, 2.1 and 2.4 mmHg, respectively. CST and GAT correlated well with each other. NCT values were lower than those of GAT and CST (all p < 0.05), whereas CST values did not differ from the GAT readings. Central corneal thickness, corneal biomechanical properties and age showed significant correlation with the differences of CST-NCT and GAT-NCT. CONCLUSIONS: In SO tamponade eyes, NCT obtains lower IOP than other tonometry techniques, and CST is highly consistent with GAT. CST offers an optional non-contact method for measuring postoperative IOP in SO tamponade eyes.

Evaluation of Four Different Restorative Materials for Restoration of the Periodontal Condition of Wedge-Shaped Defect: A Comparative Study.

BACKGROUND This study aimed to conduct a clinical evaluation of four restorative materials for restoration of dental wedge-shaped defect (WSD) and their impacts on periodontal tissues. MATERIAL AND METHODS A total of 280 maxillary premolars with dental WSD were selected from 106 patients; the patient cases were divided into eight groups according to different combinations of restorative materials (flowable resin composites, Dyract compomers, glass ionomer cement (GIC), light-curing composite resin), and WSD positions (approaching gingival and subgingival positions). Gingival crevicular fluid (GCF) volume, levels of aspartate aminotransferase (AST), alkaline phosphatase (ALP), and interleukin-1ß (IL-1ß) in GCF were analyzed, while probing depth (PD), plaque index (PLI), and sulcus bleeding index (SBI) were also measured. The periodontal conditions of all patients were followed prior to restoration, as well as six months and 12 months after restoration. RESULTS After six months of restoration, the overall clinical success rates of flowable resin composites, Dyract compomers, and light-curing composite resin were greater than those of GIC. GCF volume, GCF-AST, IL-1ß levels, PD, PLI, and SBI of cases restored by GIC were higher than those restored by the other three materials. After 12 months of restoration, the overall clinical success rates of flowable resin composites and Dyract compomers were greater than those of light-curing composite resin and GIC. GCF volume, GCF-AST, GCF-ALP, IL-1ß levels, PD, PLI, and SBI of cases restored by GIC were higher than those restored by the other three materials. CONCLUSIONS Our study provided evidence that the clinical efficacy of flowable resin composites, Dyract compomers, and light-curing composite resin was greater than that of GIC for restoration of dental WSD.

Air tamponade in vitrectomies for primary rhegmatogenous retinal detachment caused by superior breaks.

The effectiveness of filtered air tamponade for superior retinal breaks was well established. This study was performed to compare the treatment efficacy of pars plana vitrectomies (PPV) with filtered air and silicone oil (SO) for patients with rhegmatogenous retinal detachment (RRD) caused by superior breaks with no or mild proliferative vitreoretinopathy. Patients of RRD with superior breaks who underwent PPV with filtered air (Group A) and SO (Group S) tamponade were reviewed retrospectively. Age, gender, laterality, lens status, duration of symptoms, macular status, proliferative vitreoretinopathy grade, use of perfluorocarbon liquid, early and late postoperative complications, follow-up duration were acquired. The primary anatomic reattachment after the first surgery and the final rate of successful reattachment was compared as the main outcome. Secondary outcomes were long-term postoperative best-corrected visual acuity (BCVA), rate of deferred cataract removal, surgical complications and total surgery number. The primary anatomic success rate was 88% (14/16 eyes) in Group A and 100% (16/16 eyes) in group S, which was not significantly different (P = .484). Both groups achieved 100% final anatomic success. The rate of cataract removal was 57.1% and 100% (P = .016), and the duration from first surgery to cataract surgery was 231.38 ±â€…241.23 and 156.36 ±â€…110.09 days (P = .428) for group A and group S, respectively. The rate of postoperative epiretinal membrane was 21.4% vs 25.0% (P = 1.000). Postoperative BCVA was associated with preoperative BCVA after multiple linear analysis. The primary and final anatomic success rate for PPV with air tamponade and SO in treating RRD with superior breaks were not statistically different. The rate of deferred cataract removal was higher in patients with SO as tamponade.

Levilactobacillus brevis surface layer protein B promotes liposome targeting to antigen-presenting cells in Peyer's patches.

Liposome targeting by conjugation with specific ligands and cross-linking reagents is an attractive strategy for active drug delivery. Here, we demonstrated the potential of surface layer protein (Slp) B from Levilactobacillus brevis JCM 1059 as a specific ligand to antigen-presenting cells (APCs) in Peyer's patches. L. brevis JCM 1059 SlpB-coated liposomes (SlpB-LPs) showed higher resistance to various pH values and bile acids compared to non-coated liposomes (LPs). SlpB-LP showed a significantly higher uptake into dendritic cell-like differentiated THP-1 cells than LP did. The SlpB-LP-conjugated α-galactosylceramide (αGalCer) promoted the production of IL-12 (p40) and TNF-α by THP-1 cells. Furthermore, SlpB-LP showed significantly higher delivery efficiency into APCs underlaying microfold (M) cells in Peyer's patches after oral administration in BALB/c mice and enhanced IL-12 production when αGalCer was conjugated to SlpB-LP. In conclusion, the present study demonstrates the therapeutic potential of SlpB-coated LP to deliver immunomodulatory components to the gut immune system.

An Up-To-Date Overview of Dental Tissue Regeneration Using Dental Origin Mesenchymal Stem Cells: Challenges and Road Ahead.

Stem cells (SCs) research has experienced exponential growth in recent years. SC-based treatments can enhance the lives of people suffering from cardiac ischemia, Alzheimer's disease, and regenerative drug conditions, like bone or loss of teeth. Numerous kinds of progenitor/SCs have been hypothesized to depend on their potential to regain and/or heal wounded tissue and partly recover organ function. Growing data suggest that SCs (SCs) are concentrated in functions and that particular tissues have more SCs. Dental tissues, in particular, are considered a significant cause of mesenchymal stem cells (MSCs) cells appropriate for tissue regeneration uses. Tissue regeneration and SCs biology have particular attention in dentistry because they may give a novel method for creating clinical material and/or tissue redevelopment. Dental pulp, dental papilla, periodontal ligament, and dental follicle contain mesenchymal SCs. Such SCs, which must be identified and cultivated in specific tissue culture environments, may be used in tissue engineering applications such as tooth tissue, nerve regeneration, and bone redevelopment. A new cause of SCs, induced pluripotent SCs, was successfully made from human somatic cells, enabling the generation of the patient and disease-specific SCs. The dental SC's (DSCs) multipotency, rapid proliferation rate, and accessibility make it an ideal basis of MSC for tissue redevelopment. This article discusses current advances in tooth SC investigation and its possible application in tissue redevelopment.

Desktop-stereolithography 3D printing of a radially oriented extracellular matrix/mesenchymal stem cell exosome bioink for osteochondral defect regeneration.

Mitochondrial dysfunction and oxidative stress damage are hallmarks of osteoarthritis (OA). Mesenchymal stem cell (MSC)-derived exosomes are important in intercellular mitochondria communication. However, the use of MSC exosomes for regulating mitochondrial function in OA has not been reported. This study aimed to explore the therapeutic effect of MSC exosomes in a three dimensional (3D) printed scaffold for early OA therapeutics. Methods: We first examined the mitochondria-related proteins in normal and OA human cartilage samples and investigated whether MSC exosomes could enhance mitochondrial biogenesis in vitro. We subsequently designed a bio-scaffold for MSC exosomes delivery and fabricated a 3D printed cartilage extracellular matrix (ECM)/gelatin methacrylate (GelMA)/exosome scaffold with radially oriented channels using desktop-stereolithography technology. Finally, the osteochondral defect repair capacity of the 3D printed scaffold was assessed using a rabbit model. Results: The ECM/GelMA/exosome scaffold effectively restored chondrocyte mitochondrial dysfunction, enhanced chondrocyte migration, and polarized the synovial macrophage response toward an M2 phenotype. The 3D printed scaffold significantly facilitated the cartilage regeneration in the animal model. Conclusion: This study demonstrated that the 3D printed, radially oriented ECM/GelMA/exosome scaffold could be a promising strategy for early OA treatment.

Cement Distribution Patterns Are Associated with Recompression in Cemented Vertebrae After Percutaneous Vertebroplasty: A Retrospective Study.

OBJECTIVE: To reevaluate the cement distribution patterns and further investigate associations between cement distribution patterns and the occurrence rates of recompression in cemented vertebrae after percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fractures. METHODS: Two hundred twenty-four patients with a mean age of 71.9 years were enrolled and treated with single-level PVP between June 2012 and July 2015. The mean follow-up time was 16.5 months. Data from medical records and radiographs were collected and analyzed. Cement distribution patterns were divided into 4 cement distribution patterns extending from the traditional 2 patterns: interlocked solid pattern (LS) and uninterlocked solid pattern (ULS); contiguous trabecular pattern (CT) and discontiguous trabecular pattern (DCT). Differences in treatment efficacy and the occurrence rates of recompression in cemented vertebrae were compared for both groups using the Wilcoxon rank sum test and chi-squared test. RESULTS: Thirty-seven patients who underwent PVP developed recompression in cemented vertebrae. Recompression in cemented vertebrae was significantly more frequent in the ULS and DCT groups than in the LS and CT groups (P < 0.05 or 0.001), with the Visual Analogue Scale score at the time of final follow-up was also significantly higher in the ULS and DCT groups (P < 0.001). CONCLUSIONS: Significant associations were found between cement distribution patterns and recompression in cemented vertebrae, which affected the clinical outcome in patients after PVP. A higher incidence of recompression in cemented vertebrae was seen in patients with treated vertebrae exhibiting ULS pattern or DCT pattern.

Tumor priming using metronomic chemotherapy with neovasculature-targeted, nanoparticulate paclitaxel.

Normalization of the tumor microenvironment is a promising approach to render conventional chemotherapy more effective. Although passively targeted drug nanocarriers have been investigated to this end, actively targeted tumor priming remains to be explored. In this work, we demonstrate an effective tumor priming strategy using metronomic application of nanoparticles actively targeted to tumor neovasculature. F56 peptide-conjugated paclitaxel-loaded nanoparticles (F56-PTX-NP) were formulated from PEGylated polylactide using an oil in water emulsion approach. Metronomic F56-PTX-NP specifically targeted tumor vascular endothelial cells (ECs), pruned vessels with strong antiangiogenic activity and induced thrombospondin-1 (TSP-1) secretion from ECs. The treatment induced tumor vasculature normalization as evidenced by significantly increased coverage of basement membrane and pericytes. The tumor microenvironment was altered with enhanced pO2, lower interstitial fluid pressure, and enhanced vascular perfusion and doxorubicin delivery. A "normalization window" of at least 9 days was induced, which was longer than other approaches using antiangiogenic agents. Together, these results show that metronomic, actively-targeted nanomedicine can induce tumor vascular normalization and modulate the tumor microenvironment, opening a window of opportunity for effective combination chemotherapies.

Intrinsically Mn2+-Chelated Polydopamine Nanoparticles for Simultaneous Magnetic Resonance Imaging and Photothermal Ablation of Cancer Cells.

Theranostic agents for magnetic resonance imaging (MRI) guided photothermal therapy have attracted intensive interest in cancer diagnosis and treatment. However, the development of biocompatible theranostic agents with high photothermal conversion efficiency and good MRI contrast effect remains a challenge. Herein, PEGylated Mn2+-chelated polydopamine (PMPDA) nanoparticles were successfully developed as novel theranostic agents for simultaneous MRI signal enhancement and photothermal ablation of cancer cells, based on intrinsic manganese-chelating properties and strong near-infrared absorption of polydopamine nanomaterials. The obtained PMPDA nanoparticles showed significant MRI signal enhancement for both in vitro and in vivo imaging. Highly effective photothermal ablation of HeLa cells exposed to PMPDA nanoparticles was then achieved upon laser irradiation for 10 min. Furthermore, the excellent biocompatibility of PMPDA nanoparticles, because of the use of Mn2+ ions as diagnostic agents and biocompatible polydopamine as photothermal agents, was confirmed by a standard MTT assay. Therefore, the developed PMPDA nanoparticles could be used as a promising theranostic agent for MRI-guided photothermal therapy of cancer cells.

[The reason and prevention of upper cervical reoperations].

OBJECTIVE: To discuss the reasons for the operation performed on 13 patients with upper cervical disease and to explore the management and prevention of upper cervical disease. METHODS: Thirteen patients with upper cervical disease were retrospectively reviewed. The reason for of reoperations on these patients were analyzed. The measures to reduce upper cervical operational complication and bad prognosis were discussed to avoid reoperations. RESULTS: The reasons for reoperations included 9 cases with unstable or re-dislocated atlantoaxial joint, 10 cases with residual spinal cord compression, 1 case with malposition of odontoid screw, 1 case with adjacent cervical spine regression, 1 case with occipital-cervical fusion failure, 1 case with spinal cord injury during operation, 1 case with bone-plant slipped into canales spinalis, and 1 case with demand to take out internal fixation for aggravated symptom. CONCLUSIONS: The common reasons for upper cervical reoperations were due to instability or redislocation of atlantoaxial joint and residual of spinal cord compression. Some measures such as reducing operate miss, using firm internal fixation and decompressing were advisable to decrease the incidence of reoperations.

Sustained delivery of BMP-2 enhanced osteoblastic differentiation of BMSCs based on surface hydroxyapatite nanostructure in chitosan-HAp scaffold.

The surface characteristics of biomaterials, especially regarding the sustained delivery of bone morphogenetic protein-2 (BMP-2), can possibly provide a novel and effective drug delivery system that can enhance osteogenesis. In this study, we evaluated the BMP-2 adsorption and release ability of the surface biomimetic hydroxyapatite (HAp) nanostructure on a new HAp-coated genipin-chitosan conjugation scaffold (HGCCS), and the resulting osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) in vitro. HGCCS exhibited a loading efficiency of 65% (1.30 µg), which is significantly higher than 28% (0.56 µg, p < 0.01) for the genipin cross-linked chitosan framework, as quantified by an enzyme-linked immunosorbent assay. More importantly, we found that the release of BMP-2 from HGGCS sustained for at least 14 days in simulated body fluid in vitro, which is much better than the burst release within 3 days for CGF. Moreover, the BMP-2 release from HGCCS induced an increase in alkaline phosphatase activity as an indicator of osteogenic differentiation of seeded BMSCs for 14 days in vitro. HGCCS also stimulated a high mRNA expression of osteogenic differentiation makers, runt-related transcription factor 2 for 14 days, osteopontin for 3 days, and osteocalcin for 14 days. The results of this study suggest that the surface biomimetic HAp nanostructure of HGCCS used as a delivery system for BMP-2 is capable of promoting osteogenic differentiation in vitro. These findings demonstrated that HAp nanostructure assembled on organic porous scaffold could work as both calcium source and absorption/release platform, which opened a new research avenue for cell growth factor release, and provided a promising strategy for design and preparation of bioactive scaffold for bone tissue engineering.

Development of a gene/drug dual delivery system for brain tumor therapy: potent inhibition via RNA interference and synergistic effects.

Malignant brain tumors are characterized by three major physiological processes: proliferation, angiogenesis, and invasion. Traditional cytotoxic chemotherapies (e.g. Paclitaxel) control the tumor by blocking growth and proliferation mechanisms, but leave angiogenesis and invasion unchecked. We identified Matrix metalloproteinase-2 (MMP-2), an essential proteinase regulating brain tumor invasion and angiogenesis, as one of the therapeutic target. A designer RNAi plasmid was developed, and complexed with the gene carrier polyethylenimine (PEI), in an effort to specifically suppress MMP-2 expression in tumor cells. The gene and a cytotoxic drug Paclitaxel were then dual-encapsulated in PLGA based submicron implants to achieve a sustained release of both agents. Potent inhibition effects on MMP-2 mRNA and protein expression, in vitro cell angiogenesis and invasion were demonstrated both on the PEI/DNA nanoparticles alone, and on the PEI/DNA nanoparticles embedded in microfibers. Most importantly, through in vivo test on intracranial xenograft tumor model in BALB/c nude mice, it was proved that the gene/drug dual delivery microfibers are able to impose significant tumor regression compared with single drug delivery microfibers and commercial drug treatment, showing evidence for synergistic therapeutic efficacy.

In vitro investigation on the biodegradability and biocompatibility of genipin cross-linked porcine acellular dermal matrix with intrinsic fluorescence.

As a biocompatible and bioactive natural tissue engineering scaffold, porcine acellular dermal matrix (PADM) has limitations for the application in tissue regeneration due to its low strength and rapid biodegradation. Here, purified PADM was modified by a nontoxic cross-linker (genipin) to enhance its mechanical properties and improve its resistance to enzymatic degradation. In vitro testing results demonstrated that the stiffness of the genipin cross-linked PADM was improved and biodegradation rate was decreased. Results of cell proliferation assays showed that the cross-linking reaction by genipin did not undermine the cytocompatibility of PADM. Furthermore, genipin cross-linking imparted an observable fluorescence allowing visualization of the scaffold's three-dimensional (3D) porous structure and cell distribution by confocal laser scanning microscopy (CLSM). Immunostaining of the cell nuclei and cytoskeleton indicated that MC3T3-E1 preosteoblasts were tightly adhered to and uniformly distributed onto the cross-linked PADM scaffold. Results of this study suggest that the 3D porous genipin cross-linked PADM with intrinsic fluorescence may have broader applications for tissue engineering scaffolds where higher mechanical stiffness is needed.

Construction of a fluorescent nanostructured chitosan-hydroxyapatite scaffold by nanocrystallon induced biomimetic mineralization and its cell biocompatibility.

Biomaterial surfaces and their nanostructures can significantly influence cell growth and viability. Thus, manipulating surface characteristics of scaffolds can be a potential strategy to control cell functions for stem cell tissue engineering. In this study, in order to construct a hydroxyapatite (HAp) coated genipin-chitosan conjugation scaffold (HGCCS) with a well-defined HAp nanostructured surface, we have developed a simple and controllable approach that allows construction of a two-level, three-dimensional (3D) networked structure to provide sufficient calcium source and achieve desired mechanical function and mass transport (permeability and diffusion) properties. Using a nontoxic cross-linker (genipin) and a nanocrystallon induced biomimetic mineralization method, we first assembled a layer of HAp network-like nanostructure on a 3D porous chitosan-based framework. X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) analysis confirm that the continuous network-like nanostructure on the channel surface of the HGCCS is composed of crystalline HAp. Compressive testing demonstrated that the strength of the HGCCS is apparently enhanced because of the strong cross-linking of genipin and the resulting reinforcement of the HAp nanonetwork. The fluorescence properties of genipin-chitosan conjugation for convenient monitoring of the 3D porous scaffold biodegradability and cell localization in the scaffold was specifically explored using confocal laser scanning microscopy (CLSM). Furthermore, through scanning electron microscope (SEM) observation and immunofluorescence measurements of F-actin, we found that the HAp network-like nanostructure on the surface of the HGCCS can influence the morphology and integrin-mediated cytoskeleton organization of rat bone marrow-derived mesenchymal stem cells (BMSCs). Based on cell proliferation assays, rat BMSCs tend to have higher viability on HGCCS in vitro. The results of this study suggest that the fluorescent two-level 3D nanostructured chitosan-HAp scaffold will be a promising scaffold for bone tissue engineering application.