Modified kyphoplasty with controllable balloon dilatation for treatment of thoracolumbar osteoporotic vertebral compression fractures.

PURPOSE: To investigate the surgical effects of modified kyphoplasty with controllable balloon dilatation for treatment of thoracolumbar osteoporotic vertebral compression fractures (OVCF). METHODS: From April 2013 to October 2017, a total of 53 patients with thoracolumbar OVCF were treated with controllable balloon percutaneous kyphoplasty (C-PKP). Peri-operative parameters including days from injury to operation, operation time, injected cement volume, cement leakage and complications were collected. Visual analogue scale (VAS) and Cobb angle before and after operation were applied to evaluate surgical effects. Moreover, a total of 53 cases treated with traditional balloon of percutaneous kyphoplasty were retrospectively analyzed and compared with C-PKP in above parameters. RESULTS: C-PKP achieved significant fewer events of cement leakage (type C) than that of traditional PKP (5/53 vs 13/53, p < 0.01). The patients were followed up for 10.8 ± 4.2 months; VAS and Cobb angle of the injured vertebra in both two groups at three days and final follow-up were significantly improved compared with that before surgery (p < 0.05), while there were no significant differences between the two groups regarding the VAS and Cobb angle at corresponding time points (p > 0.05). CONCLUSIONS: C-PKP technology is a safe and efficient way for the treatment of thoracolumbar OVCF, and it can reduce cement leakage.

Selective recovery of salt from coal gasification brine by nanofiltration membranes.

The selective extraction and concentration of salt from coal gasification brine (CGB) by nanofiltration membranes is a promising technology to achieve near-zero liquid discharge of coal gasification wastewater. To investigate the feasibility of recovery of salts and the interaction of organic compounds, multivalent ions and monovalent ions on the rejection ratio, three nanofiltration membranes (OWNF1, NF270 and Desal-5 DK) with an 1812 spiral-wound module were used in crossflow filtration. The rejection mechanism was analyzed by comparing the rejection performance as a function of the operation pressure (increasing from 1.0 MPa to 2.5 MPa), the concentration (increasing from 10,000 mg/L to 25,000 mg/L) and pH values (increasing from 3.0 to 10.0). The concentrations of anions and cations were determined using an ion chromatographic analyzer and an inductively coupled plasma emission spectrometer, respectively. The results show that the rejection of sulfate and the chemical oxygen demand were higher than 92.12% and 78.84%, respectively, at appropriate operation, while negative rejection of chloride was observed in the CGB. The decreasing rejection of organic compounds was due to swelling of the membrane pore in high-concentration solutions. Meanwhile, the organic compounds weakened the negative charge of the membrane active layer, consequently decreasing the ion rejection. More than 85% of the sodium chloride could be recovered, indicating that this technology is suitable for resource recovery from CGB and near-zero liquid discharge of coal gasification industry.

Production of xylonic acid by Klebsiella pneumoniae.

The glucose oxidation pathway is important for glucose catabolism in Klebsiella pneumoniae. Gluconic acid and 2-ketogluconic acid are intermediates of this pathway, and the production of these two chemicals has been developed in K. pneumoniae mutants. Catalysis characteristic research in this study has shown that xylose is a suitable substrate of the glucose dehydrogenase of this pathway. Here, using xylose as substrate, xylonic acid was accumulated in the broth of K. pneumoniae culture, and this process was dependent upon acidic conditions. Using a mixture of glucose and xylose as substrates, a mixture of xylonic acid and gluconic acid was produced by the Δgad mutant of K. pneumoniae; gluconic acid was synthesized early, and xylonic acid synthesis began after most glucose was consumed. Using the hydrolysate of bamboo as substrate, mixture of 33 g/L gluconic acid and 14 g/L xylonic acid were produced by K. pneumoniae Δgad. In fed-batch fermentation, 103 g/L xylonic acid was produced after 79 h culture, with a conversion ratio of 1.11 g/g. This is the first report of xylonic acid produced by K. pneumoniae. Production of xylonic acid and gluconic acid using bamboo hydrolysate is a novel approach for biomass utilization.

Laccase-mediated formation of hydrogels based on silk-elastin-like protein polymers with ultra-high molecular weight.

As artificial extracellular matrix-like materials, silk-elastin-like protein (SELP) hydrogels, with excellent mechanical properties, high tunability, favorable biocompatibility, and controlled degradability, have become an important candidate in biomedical materials. In this study, SELP is composed of silk-like (GAGAGS) and elastin-like (GXGVP) tandem repeats, in which X residues are set as tyrosine and lysine. Furthermore, SELP polymers are prepared via SpyTag/SpyCatcher. To explore a gentler and more efficient enzymatic crosslinking method, an innovative method was invented to apply laccase to catalyze the formation of SELP hydrogels. Gelation could be successfully achieved in 2-5 min . SELP hydrogels mediated by laccase had the characteristic of low swelling rate, which could maintain a relatively stable shape even when immersed in water, and hence had the potential to be further developed into injectable biomaterials. Additionally, SELP hydrogels cross-linked by laccase showed excellent biocompatibility verified by L929 and HEK 293 T cells with cell viability >93.8 %. SELP hydrogels also exhibit good properties in sustained drug release and cell encapsulation in vitro. This study demonstrates a novel method to construct SELP hydrogels with excellent biocompatibility and expands the possibility of SELP-based material applications in biomedical fields.

The underlying mechanism in gel formation and its mathematical simulation during anionic polyacrylamide solution ultrafiltration process.

A dead-end ultrafiltration cup was continuously operated to investigate the underlying mechanisms of membrane fouling caused by gel layer in this paper. Anionic polyacrylamide was used as a model foulant for gel formation process in various ultrafiltration processes by two kinds of ultrafiltration membrane, e.g., polyvinylidene fluoride (PVDF) membrane (OM) and TiO2/Al2O3-PVDF membrane (MM); then, a gel formation model was established and systematically assessed. The results show that the gel formation process in ultrafiltration can be divided into three stages: "slow-rapid-slow" flux decay curve. The R2 value of the simulation curve was still higher than 0.90 for both OM and MM. Based on the current cognition, the proposed gel layer formation mechanism and mathematical model were feasible.

Recent progress in the improvement of the coupling efficiency of "difficult sequences" in peptide synthesis.

Even though chemistry is now in place that potentially allows high coupling efficiencies to be attained, successful coupling is usually a challenge when so-called "difficult sequences" is encountered in peptide synthesis. Some factors that affect the coupling efficiency have been discussed and related methods to overcome those obstacles have been introduced in present review. All suggestions proposed here are valuable and also feasible to improve the coupling completeness in both liquid-phase or solid-phase

Enhancing the bioactivity of Poly(lactic-co-glycolic acid) scaffold with a nano-hydroxyapatite coating for the treatment of segmental bone defect in a rabbit model.

PURPOSE: Poly(lactic-co-glycolic acid) (PLGA) is excellent as a scaffolding matrix due to feasibility of processing and tunable biodegradability, yet the virgin scaffolds lack osteoconduction and osteoinduction. In this study, nano-hydroxyapatite (nHA) was coated on the interior surfaces of PLGA scaffolds in order to facilitate in vivo bone defect restoration using biomimetic ceramics while keeping the polyester skeleton of the scaffolds. METHODS: PLGA porous scaffolds were prepared and surface modification was carried out by incubation in modified simulated body fluids. The nHA coated PLGA scaffolds were compared to the virgin PLGA scaffolds both in vitro and in vivo. Viability and proliferation rate of bone marrow stromal cells of rabbits were examined. The constructs of scaffolds and autogenous bone marrow stromal cells were implanted into the segmental bone defect in the rabbit model, and the bone regeneration effects were observed. RESULTS: In contrast to the relative smooth pore surface of the virgin PLGA scaffold, a biomimetic hierarchical nanostructure was found on the surface of the interior pores of the nHA coated PLGA scaffolds by scanning electron microscopy. Both the viability and proliferation rate of the cells seeded in nHA coated PLGA scaffolds were higher than those in PLGA scaffolds. For bone defect repairing, the radius defects had, after 12 weeks implantation of nHA coated PLGA scaffolds, completely recuperated with significantly better bone formation than in the group of virgin PLGA scaffolds, as shown by X-ray, Micro-computerized tomography and histological examinations. CONCLUSION: nHA coating on the interior pore surfaces can significantly improve the bioactivity of PLGA porous scaffolds.