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Plastics are widely used in human daily life, which bring great convenience. Nevertheless, the disposal of a large amount of plastic wastes also brings great pressure to the environment. Polyethylene terephthalate (PET) is a polymer thermoplastic material produced from petroleum. It has become one of the most commonly used plastics in the world due to its durability, high transparency, light weight and other characteristics. PET can exist in nature for a long time due to its complex structure and the difficulty in degradation, which causes serious pollution to the global ecological environment, and threatens human health. The degradation of PET wastes has since become one of the global challenges. Compared with physical and chemical methods, biodegradation is the greenest way for treating PET wastes. This review summarizes the recent advances on PET biodegradation including microbial and enzymatic degradation of PET, biodegradation pathway, biodegradation mechanisms, and molecular modification of PET-degrading enzymes. In addition, the prospect for achieveing efficient degradation of PET, searching and improving microorganisms or enzymes that can degrade PET of high crystallinity are presented, with the aimto facilitate the development, application and molecular modification of PET biodegradation microorganisms or enzymes.
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Humans , Polyethylene Terephthalates/metabolism , Polymers , Biodegradation, Environmental , PetroleumABSTRACT
Objective To investigate the effects of dexmedetomidine (DEX) on the mRNA expression of triggering receptor expressed on myeloid cells 1 (TREM-1) in peripheral blood mononuclear cells of rats with acute obstructive suppurative cholangitis (AOSC).Methods Sixty healthy male Wistar rat models of AOSC induced by complete common bile duct ligation and injection of E.coli into the bile duct through an intubation tube were replicated successfully.After modeling,the peripheral blood was collected and mononuclear cells were isolated and cultured.According to random number table method,the mononeuclear cells were divided into model group (no drug added in culture of mononuclear cells) and low,medium and high dose DEX groups (final concentrations 0.4,0.8,1.2 μg/L DEX were in low,medium and high DEX mononuclear cell cultures,respectively).After the mononuclear cells were cultured for 24 hours,the levels of tumor necrosis factor-α (TNF-α),interleukins (IL-1 and IL-6) in the supernatant of the cultured mononuclear cells were detected by enzyme linked immunosorbent assay (ELISA).The level of C-reactive protein (CRP) was detected by immunity transmission turbidimetry.The expression of TREM-1 mRNA in the mononuclear cells was detected by reverse trantscription-polymerase chain reaction (RT-PCR).Results Compared with the model group,the levels of TNF-α,IL-1,IL-6,CRP were decreased,the TREM-1 mRNA expressions were down-regulated in the different DEX dose groups,and the degrees of descent in medium and high dose groups were more significant than those in low dose group [TNF-oα (ng/L):95.5±8.6,88.9±5.3 vs.131.1 ± 14.2;IL-1 (ng/L):53.5±8.3,48.3 ± 6.7 vs.73.7 ± 12.8;IL-6 (ng/L):266.9±26.2,252.1 ± 17.7 vs.349.9±40.4;CRP (ng/L):4.3 ± 1.1,3.9 ±0.7 vs.5.6 ± 1.7;TREM-1 mRNA (A value):0.43 ± 0.18,0.39 ± 0.16 vs.0.65 ±0.25,all P ＜ 0.05].Conclusion DEX can down-regulate the expression of TREM-1 mRNA and inhibit the formation and secretion of inflammatory factors TNF-α,IL-1,IL-6 and CRP in peripheral blood mononuclear cells of rats with ASOC.
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Objective To investigate the effects of microRNA-294 (miR-294) on tumor necrosis factor-α (TNF-α),interleukin-6 (IL-6) and high mobility group box 1 (HMGB 1) secretion in sepsis by targeting triggering receptor expressed on myeloid cell-1 (TREM-1).Methods miRNA-294 was predicted to regulate TREM-1 specially through bioinformatics analysis.Mice macrophage cell lines RAW264.7 were cultured in vitro,the cells were divided into non-inflammatory stage and inflammatory stage,and the cells in the two stages were subdivided into five groups as follows:normal control (NC),NC mimic transfection (NCm),NC inhibitor transfection (NCi),miR-294 mimic transfection (miR-294m) and miR-294 inhibitor transfection (miR-294i) groups.The ability of miR-294 was confirmed with dual-luciferase activity assay.At non-inflammatory stage,the cells were transfected with mimic or inhibitor of miR-294 or NC using TurboFectTM siRNA Transfection Reagent for 48 hours,mRNA expression of TREM-1 was detected by real-time reverse transcription-polymerase chain reaction (RT-PCR).At inflammatory stage,6 hours after stimulation by lipopolysaccharide (LPS,1 mg/L),the concentrations of TNF-α,IL-6 and HMGB1 were determined by enzyme linked immunosorbent assay (ELISA),the protein expression of TREM-1 was determined by Western Blot.Results ① Dual-luciferase activity assay demonstrated that TREM-1 was the target of miR-294.② In non-inflammatory stage,the expression of TREM-1 mRNA (2-ΔΔ~) in miR-294m group was significantly lower than that of the NC and NCm groups (0.673 ± 0.049 vs.1.000 ± 0.003,0.915 ± 0.039,t1=2.184,t2=5.421,both P＜0.001),the expression of TREM-1 protein (gray scale) was (50.00 ± 1.19)％ of NCm group (t=41.586,P＜0.001).③ In inflammatory stage,the concentrations of TNF-α (ng/L) in miR-294m group was significantly lower than that of the NC group (1 547.18 ±47.18 vs.2 702.11 ± 327.20,t=4.212,P=0.010),the concentrations of IL-6 (ng/L) was significantly lower than that of the NC and NCm groups (505.28 ± 33.33 vs.837.66 ± 69.43,918.72 ± 119.39,t1 =4.382,P1=0.015; t2=5.451,P2=0.021),the level of TREM-1 protein (gray scale) was (51.33 ±0.88)％ of NCm group (t=63.368,P＜0.001).Conclusion miR-294 reduce TNF-α and IL-6 secretion in LPS-induced RAW264.7 through inhibiting the expression of TREM-1 specifically.
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Objective To evaluate the effects of propofol on TREM-1 expression in THP-1 cells stimulated by lipo-polysaccharide (LPS). Methods Cells were divided into 7 groups: (1) control group; (2) LPS group that was exposed to LPS in final concentration of 100μg/L;(3) Progroup that was incubated with 100μmol/L propofol;(4-7) groups combined 100μg/L LPS with propofol at different dose of 12.5μmol/L (P1 group), 25μmol/L (P2 group), 50μmol/L (P3 group), 100μmol/L (P4 group) respectively. After 16 hours of incubation, the TNF-α concentration in supernatants were measured by ELISA. TREM-1 expression were examined by FACS and TREM-1 mRNA were detected using qRT-PCR. Results TREM-1 on THP-1 increased significantly in group P3 and group P4 compared with LPS group (P<0.05). The concentra-tions of TNF-αin P3 and P4 (P<0.05) decreased substantially in supernatant compared with LPS group. TREM-1 mRNA transcription level in group LPS rise considerably (P < 0.05) compared to that in control group, and it dropped greatly in group P4 (P <0.05) compared with that in group LPS. Conclusion Propofol could enhance TREM-1 expression on sur-face of THP-1 stimulated by LPS. Propofol reduces TNF-αlevel in culture supernatant. And propofol may restrain TREM-1 mRNA expression.
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With the continuous improvement and innovation of modern engineering technology and biomedical technology,many efforts and process have been made on multifunctional prosthesis systems and have gained more and more attentions.The multifunctional powered prosthesis has become one of the research areas in the current muscular rehabilitation medicine and neural engineering.The bionic control of prosthesis,especially using the neural signal to control the upper prosthesis effectively,is one of the most important fields of prosthesis technology.Choosing the proper neural signals seems to be particularly important for bionic prosthetic control strategy.Currently,several different signal controls such as EMG control,EEG control,voice signal control and peripheral nerve signal control have been proposed and investigated for the bionic control of multi-function prosthesis.This paper reviews the latest efforts and progress of multifunctional upper prosthesis.
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Objective To describe the surgical technique in reconstructing anterior cruciate ligament (ACL) with six strands harmstring tendon graft fixed by bioabsurbable rigidfix cross pins under arthroseopy and to e-valuate its efficacy. Methods From March 2005 to June 2008,39 patients with ACL injury were treated with ACL reconstruction by transplantation of six strands autogenous harmstring tendon , fixed by bioabsorbable rigidfix cross pins in femoral side. There are 22 male and 17 female,ages from 22 to 55 (the average age is 37). 19 cases were hurt in traffic accident, and another 20 cases in accidental injury. The state of illness is 7 days to 38 months. 13 cases merge the meniscus rupture, and 4 cases of meniscus suture,8 partial meniscectomy, 1 meniscectomy were performed simultaneously ;4 cases associating with the medial collateral ligaments Ⅲ degree injure underwent medial collateral ligament neo-plasty or reconstruction ;no cases merge posterior cruciate ligament injury, the patients were followed up 12 to 51 months , Pre-and post-operative knee joint function and stability were evaluated according to the Lysholm scoring scale system and the results of KT-2000 arthrometer , the clinical results and the reliability of the fixation were analyzed. Results 32 patients were followed-up and there is no limitation of the extention in the knee joints. The flexation of the knee joint is greater than 120°,and the anterior drawer test in 90° of flexation were negative in all patients. The postoperative Lachman test was strong positive in 1 case, negative in 26 cases and positive in 5 cases. The Lysholm scores was (92.6±4.2) points. The results of KT-2000 arthrometer: 31 cases 0-4.5 nun, average 3.2 mm;1 case 6. 5 mm. Conclusions It is a safe and reliable method to reconstruct ACL with six strands harmstring tendon graft fixing by bioabsorbable rigidfix cross pins under arthroscopy, and this procedure can obtain primary stabilization and long term stabilization of the autografts.
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0.05)in visual analogue scales and blood-gas results,but the respiratory recovery function in ropivacaine group was markedly better than that in the bupivacaine group(P