Biomechanical evaluation of Percutaneous endoscopic posterior lumbar interbody fusion and minimally invasive transforaminal lumbar interbody fusion: a biomechanical analysis.

In order to analyze and evaluate the stability of lumbar spine and the risk of cage subsidence after different minimally invasive fusion operations, two finite element models Percutaneous endoscopic posterior lumbar interbody fusion (PE-PLIF) and minimally invasive transforaminal lumbar interbody Fusion (MIS-TLIF) were established. The results showed that compared with MIS-TLIF, PE-PLIF had better segmental stability, lower pedicle screw rod system stress, and lower risk of cage subsidence. The results suggest that the cage with appropriate height should be selected to ensure the segmental stability and avoid the risk of the subsidence caused by the cage with large height.

[Blind area and layout optimization of parks based on the spatial supply-demand evaluation in Taiyuan City, China]. / åŸºäºŽä¾›éœ€å‡è¡¡çš„å¤ªåŽŸå¸‚å ¬å›­æœåŠ¡ç›²åŒºåŠä¼˜åŒ–å¸ƒå±€.

It is of great practical significance to identify service blind area, scientifically select park construction areas, and clarify the priority of parks' construction based on the co-ordination of supply-demand evaluation. With the urban parks within the Taiyuan Ring Expressway as the research subjects, we estimated the accessibility range and the service pressure of each park by using the application programming interface of Gaode map route planning and point of interest data to characterize their supply and demand levels. We identified the service blind areas of parks by overlay analysis, and used the location-allocation (LA) model to purposefully supply park green space. Results showed that the accessibility coverage rates of the parks by walking and bicycling within 15 minutes were 35.6% and 71.7%, respectively, indicating insufficient supply capacity of parks. The areas with large potential demand for park green space in Taiyuan were mainly concentrated in the business district of Qinxian-Changfeng Street and the Shuangta business district within Dongzhong ring road, which existed the obviously invisible blind areas. Finally, we proposed new park green space site selection proposal based on LA model. Optimization results indicated that the coverage rates of walking and bicycling within 15 minutes increased to 46.7% and 81.0%, respectively, and that the service pressure of parks was relieved. We combined the leisure demands of urban residents and the distribution of urban parks by utilizing network big data, which could promote the scientific nature and accuracy of the optimizing site selection and provide scientific method and theory basis for urban park construction.

Tumor attachment to Major intrahepatic vascular for Colorectal liver metastases.

BACKGROUND: Colorectal liver metastases attached major intrahepatic vessels has been considered to be a risk factor for survival outcome after liver resection. The present study aimed to clarify the outcomes of R1 surgery (margin < 1 mm) in CRLM patients, distinguishing parenchymal margin R1 and attached to major intrahepatic vessels R1. METHODS: In present study, 283 CRLM patients who were evaluated to be attached to major intrahepatic vessels initially and underwent liver resection following preoperative chemotherapy. They were assigned to two following groups: R0 (n = 167), R1 parenchymal (n = 58) and R1 vascular (n = 58). The survival outcomes and local recurrence rates were analyzed in each group. RESULTS: Overall, 3- and 5-year overall survival rates after liver resection were 53.0% and 38.2% (median overall survival 37 months). Five-year overall survival was higher in patients with R0 than parenchymal R1 (44.9%% vs. 26.3%, p = 0.009), whereas there was no significant difference from patients with vascular R1 (34.3%, p = 0.752). In the multivariable analysis, preoperative chemotherapy > 4 cycles, clinical risk score 3-5, RAS mutation, parenchymal R1 and CA199 > 100 IU/ml were identified as independent predictive factors of overall survival (p < 0.05). There was no significant difference for local recurrence among three groups. CONCLUSION: Parenchymal R1 resection was independent risk factor for CRLM. Vascular R1 surgery achieved survival outcomes equivalent to R0 resection. Non-anatomic liver resection for CRLM attached to intrahepatic vessels might be pursued to increase patient resectability by preoperative chemotherapy.

PhlG mediates the conversion of DAPG to MAPG in Pseudomonas fluorescens 2P24.

The antibiotic 2,4-diacetylphoroglucinol (2,4-DAPG), produced by the Gram-negative rod-shaped bacterium Pseudomonas fluorescens 2P24, is active against various soil-borne bacterial and fungal pathogens that cause plant diseases. Biosynthesis of 2,4-DAPG is controlled by regulating expression of the phlACBD operon at the post-transcriptional level. The phlG gene is located between the phlF and phlH genes, upstream of the phlACBD biosynthetic operon. Herein, we cloned the phlG gene, generated a phlG deletion mutant, and investigated its regulatory role in 2,4-DAPG biosynthesis. The results showed that deletion of phlG had no effect on the biosynthesis of 2,4-DAPG, but it affected conversion of 2,4-DAPG to its precursor monoacetylphloroglucinol (MAPG). The global regulatory factor encoded by gacS positively regulated expression of phlG, while rsmE negatively regulated its expression. Deleting phlG did not alter the ability of the bacterium to colonise plants or promote plant growth. These results suggest that phlG collaborates with other factors to regulate production of the antibiotic 2,4-DAPG in P. fluorescens 2P24.

Comparative study on the composition of four different varieties of garlic.

Garlic is used as a medicinal seasoning worldwide. The aim of this work was to compare four varieties of garlic: 'Taicangbaipi', 'Ershuizao', 'Hongqixing', and 'Single-clove'; among them, 'Ershuizao' and 'Hongqixing' are unique to the Sichuan Province of China. Firstly, soluble sugar, starch, and the protein content of the garlic were analysed. There was more soluble sugar in 'Single-clove', total starch in 'Hongqixing', and protein content in 'Ershuizao' relative to the other three varieties, respectively. Gas chromatography-mass spectrometry analysis showed that 'Ershuizao' and 'Hongqixing' contained high levels of 5-hydroxymethylfurfural, which has antitumor, antioxidant, and cytoprotective effects. Indeed, the extracts from these two types of garlic were more effective at inhibiting tumour growth than that from the others. Moreover, the sulphide content and antimicrobial effects of 'Ershuizao' and 'Hongqixing' garlic were also higher than those of the other two types of garlic. In addition, changes observed in the membrane permeability and protein leakage suggest that the antimicrobial activity of the 'Ershuizao' and 'Hongqixing' extracts may be due to the destruction of the structural integrity of the cell membranes, leading to cell death.

[Distribution changes and refugia of three spruce taxa since the last interglacial.] / 末次间冰期以来3种云杉属植物的历史分布变迁及避难所.

Based on the current distribution information and 19 environmental variables data, we used the maximum entropy model to simulate the suitable distribution of Picea likiangensis var. likiangensis, P. purpurea and P. wilsonii in the last interglacial, Last Glacial Maximum, Mid- Holocene and present. The results from such modelling were validated by pollen data. We analyzed the relationship between species distribution dynamics and climate change, and then speculated the cryptic refugia of those species. Both the areas under the receiver operating characteristic curves and the verification results from pollen data indicated high accuracy of the model results. Results showed that isothermality was the most important factor influencing the distribution of P. likiangensis var. likiangensis and mean temperature of the warmest quarter was the most important for the distribution of both P. purpurea and P. wilsonii. Temperature was more important than precipitation in driving species distributions. Three species expanded their distribution ranges in Last Glacial Maximum due to their cold-adapted ecological habitat and the deep canyon topography feature which benefited their migration. There might be refugia of both P. wilsonii and P. purpurea in last interglacial, and they respectively located in Shennongjia Mountain in Hubei and Erlang Mountain and its nearby mountains in Sichuan. Our results, to some extent, made accurate prediction of the suitable distribution of three spruce species in the key periods since last interglacial, and speculated refugia of P. purpurea and P. willsonii. Our findings provided reference for better understanding of the formation mechanism of the present distribution of Picea and prediction of distribution changes in the future and sustainable management and protection of three spruce species.

Effects of the microcrack shape, size and direction on the poroelastic behaviors of a single osteon: a finite element study.

PURPOSE: In this work, a finite element study is proposed by using the Comsol Multiphysics software to evaluate the effects of microcrack shape, size and direction on the poroelastic behaviors of a single osteon. METHODS: This finite element model is established by using the Comsol Multiphysics software, and we just focus on the comparison of the influences of those microcrack geometric parameters on the osteonal fluid pressure and velocity. RESULTS: The results show that: (1) microcracks in the osteon wall can induce a release of the fluid pressure, but enlarge the velocity in this region; (2) equal-area microcrack with ellipsoid-like shape produced a larger fluid pressure and velocity fields in the osteon than that of rectangular shape; (3) in the elliptic microcracks, the longer of the length (major semi-axis) induces a smaller fluid pressure and velocity amplitudes, whereas the width (minor axis) has little effect; (4) the direction of the microcracks (major axial direction) has an limited influence area around about 1/15 of the osteon cross-sectional area. CONCLUSIONS: This model permits the linking of the external loads and microcracks to the osteonal fluid pressure and velocity, which can be used for other purpose associate microcracks with the mechanotransduction and bone remodeling.

Posttranscriptional regulation of 2,4-diacetylphloroglucinol production by GidA and TrmE in Pseudomonas fluorescens 2P24.

Pseudomonas fluorescens 2P24 is a soilborne bacterium that synthesizes and excretes multiple antimicrobial metabolites. The polyketide compound 2,4-diacetylphloroglucinol (2,4-DAPG), synthesized by the phlACBD locus, is its major biocontrol determinant. This study investigated two mutants defective in antagonistic activity against Rhizoctonia solani. Deletion of the gidA (PM701) or trmE (PM702) gene from strain 2P24 completely inhibited the production of 2,4-DAPG and its precursors, monoacetylphloroglucinol (MAPG) and phloroglucinol (PG). The transcription of the phlA gene was not affected, but the translation of the phlA and phlD genes was reduced significantly. Two components of the Gac/Rsm pathway, RsmA and RsmE, were found to be regulated by gidA and trmE, whereas the other components, RsmX, RsmY, and RsmZ, were not. The regulation of 2,4-DAPG production by gidA and trmE, however, was independent of the Gac/Rsm pathway. Both the gidA and trmE mutants were unable to produce PG but could convert PG to MAPG and MAPG to 2,4-DAPG. Overexpression of PhlD in the gidA and trmE mutants could restore the production of PG and 2,4-DAPG. Taken together, these findings suggest that GidA and TrmE are positive regulatory elements that influence the biosynthesis of 2,4-DAPG posttranscriptionally.

Effect of the hfq gene on 2,4-diacetylphloroglucinol production and the PcoI/PcoR quorum-sensing system in Pseudomonas fluorescens 2P24.

Pseudomonas fluorescens 2P24 is an effective biological control agent of a number of soilborne plant diseases caused by pathogenic microorganisms. Among a range of secondary metabolites produced by strain 2P24, the antibiotic 2,4-diacetylphloroglucinol (2,4-DAPG) is the major determinant of its disease-suppressive capacity. In this study, we performed random mutagenesis using mini-Tn5 in order to screen for the transcriptional regulators of the phlA gene, a biosynthase gene responsible for 2,4-DAPG production. The mutant PMphlA23 with significantly decreased phlA gene expression was identified from approximately 10,000 insertion colonies. The protein sequence of the interrupted gene has 84% identity to Hfq, a key regulator important for stress resistance and virulence in Pseudomonas aeruginosa. Genetic inactivation of hfq resulted in decreased expression of phlA and reduced production of 2,4-DAPG. Furthermore, the hfq gene was also required for the expression of pcoI, a synthase gene for the LuxI-type quorum-sensing signaling molecule N-acyl-homoserine lactone. Additionally, the hfq mutation drastically reduced biofilm formation and impaired the colonization ability of strain 2P24 on wheat rhizospheres. Based on these results, we propose that Hfq functions as an important regulatory element in the complex network controlling environmental adaption in P. fluorescens 2P24.

The resistance-nodulation-division efflux pump EmhABC influences the production of 2,4-diacetylphloroglucinol in Pseudomonas fluorescens 2P24.

The polyketide metabolite 2,4-diacetylphloroglucinol (2,4-DAPG) plays a major role in the biological control of soil-borne plant diseases by Pseudomonas fluorescens 2P24. Two mutants (PM810 and PM820) with increased extracellular accumulation of 2,4-DAPG were isolated using transposon mutagenesis. The disrupted genes in these two mutants shared >80 % identity with the genes of the EmhR-EmhABC resistance-nodulation-division (RND) efflux system of P. fluorescens cLP6a. The deletion of emhA (PM802), emhB (PM803) or emhC (PM804) genes in strain 2P24 increased the extracellular accumulation of 2,4-DAPG, whereas the deletion of the emhR (PM801) gene decreased the biosynthesis of 2,4-DAPG. The promoter assay confirmed the elevated transcription of emhABC in the EmhR disrupted strain (PM801) and an indirect negative regulation of 2,4-DAPG biosynthetic locus transcription by the EmhABC efflux pump. Induction by exogenous 2,4-DAPG led to remarkable differences in transcription of chromosome-borne phlA : : lacZ fusion in PM901 and PM811 (emhA(-)) strains. Additionally, the EmhABC system in strain 2P24 was involved in the resistance to a group of toxic compounds, including ampicillin, chloramphenicol, tetracycline, ethidium bromide and crystal violet. In conclusion, our results suggest that the EmhABC system is an important element that influences the production of antibiotic 2,4-DAPG and enhances resistance to toxic compounds in P. fluorescens 2P24.

Regulation of the PcoI/PcoR quorum-sensing system in Pseudomonas fluorescens 2P24 by the PhoP/PhoQ two-component system.

A quorum-sensing locus, pcoI/pcoR, which is involved in the regulation of root colonization and plant disease-suppressive ability, was previously identified in Pseudomonas fluorescens 2P24. In this study, we performed random mutagenesis using mini-Tn5 in order to screen the upstream transcriptional regulators of pcoI, a biosynthase gene responsible for the synthesis of N-acylhomoserine lactone signal molecules. Two mutants, PM400 and PM410, with elevated pcoI gene promoter activity, were identified from approximately 10,000 insertion clones. The amino acid sequences of the interrupted genes in these two mutants were highly similar to PhoQ, a sensor protein of the two-component regulatory system PhoP/PhoQ, which responds to environmental Mg2+ starvation and regulates virulence in Salmonella typhimurium and antimicrobial peptide resistance in Pseudomonas aeruginosa. The promoter activity of pcoI was also induced under low-Mg2+ conditions in the 2P24 strain of P. fluorescens. Deletion mutagenesis and complementation experiments demonstrated that the transcription of pcoI was negatively regulated by the sensor PhoQ but positively regulated by the response regulator PhoP. Genetic evidence also indicated that transcription of the outer-membrane protein gene oprH was induced by Mg2+ starvation through regulation of the wild-type PhoP/PhoQ system. Additionally, PhoQ was involved in biofilm formation by 2P24 under low-Mg2+ conditions through a PhoP-independent pathway.

Differential control of the PcoI/PcoR quorum-sensing system in Pseudomonas fluorescens 2P24 by sigma factor RpoS and the GacS/GacA two-component regulatory system.

A quorum-sensing (QS) locus PcoI/PcoR had been identified previously in the biological control bacterium Pseudomonas fluorescens 2P24. In this paper, we investigated the upstream regulators that influence the transcription of the N-acyl homoserine lactone (AHL) biosynthase gene pcoI using a chromosomal pcoIColon, two colonslacZ fusion reporter strain. Stationary sigma factor RpoS was identified as a negative regulator of QS system using a random mini-Tn5 mutant procedure. Furthermore, deletion mutagenesis and complementation experiments demonstrated that the two-component system GacS/GacA positively regulated the QS system by upregulating pcoI transcription. However, compared with the gacA or gacS mutant, introduction of a second mutation of rpoS in the gacA(-) or gacS(-) background did not lead to further change in the transcriptional expression of the pcoI gene or the synthesis of AHL. Our results suggest that in strain 2P24, RpoS could only play its negative regulatory role on the pcoI gene under a functional GacS/GacA system background.