Publications by authors named "Guanglei Zhao"

32 Publications

Highly efficient whole-cell biosynthesis and cytotoxicity of esculin esters.

J Biotechnol 2021 Aug 29;337:46-56. Epub 2021 Jun 29.

College of Food Science and Engineering, South China University of Technology, Wushan Road 381, Guangzhou, Guangdong, 510640, China. Electronic address:

Esculin is a polyphenol with multiple bioactivities and poor lipophilicity. Therefore, a whole-cell catalytic strategy for esculin acylation was developed to improve its lipophilicity. A total of 12 strains were tested, among which Pseudomonas stutzeri exhibited the highest catalytic activity and mono-acylated regioselectivity. The conversion reached the highest level of 92.7 % at 24 h under the optimal conditions, when vinyl acetate was used as an acyl donor. The catalytic ability of P. stutzeri remained above 60 % after three cycles. Subsequently, five esculin esters with different lengths of fatty chains were synthesized and structurally identified. Of them, esculin-6'-O-octanoate, esculin-6'-O-laurate, and esculin-6'-O-myristate exhibited cytotoxicity on LO2 cells by inducing apoptosis and necrosis. The cytotoxicity of these three esters may attribute to their membrane-disrupting properties. This study provides a novel whole-cell biocatalytic strategy for the acylation of esculin and insight for application of esculin esters as a food additive or drug.
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http://dx.doi.org/10.1016/j.jbiotec.2021.06.023DOI Listing
August 2021

Antityrosinase Mechanism and Antimelanogenic Effect of Arbutin Esters Synthesis Catalyzed by Whole-Cell Biocatalyst.

J Agric Food Chem 2021 Apr 6;69(14):4243-4252. Epub 2021 Apr 6.

Department of Spine Surgery, Center for Orthopaedic Surgery, The Third Affiliated Hospital of Southern Medical University, Academy of Orthopedics of Guangdong Province, Guangzhou 510630, China.

Tyrosinase is a key enzyme responsible for enzymatic browning of fruits and vegetables and skin disorders due to overproduction of melanin. Arbutin is an inhibitor of tyrosinase; however, its high polarity and weak transdermal absorption capacity limit its applications. In this paper, a green solvent system was developed to successfully synthesize arbutin esters with improved liposolubilities (Clog values = 0.27-5.03). Among the obtained esters, arbutin undecenoate (AU) showed the strongest tyrosinase-inhibiting activity (15.6%), which was 9.0 times higher than that of arbutin. An enzyme kinetics study indicated that AU was a competitive inhibitor with reversible inhibition. The esters inhibited tyrosinase by making the secondary structure of tyrosinase looser and less stable; moreover, the interactions between tyrosinase and AU driven by metal interactions and hydrogen bonds also offered a mechanism for inhibition of AU on tyrosinase. In addition, AU (100 μM) reduced the melanin content of B16 mouse melanoma cells to 61.3% of the control group.
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http://dx.doi.org/10.1021/acs.jafc.0c07379DOI Listing
April 2021

Organic Solvent-Free Preparation of Chitosan Nanofibers with High Specific Surface Charge and Their Application in Biomaterials.

ACS Appl Mater Interfaces 2021 Mar 24;13(10):12347-12358. Epub 2021 Feb 24.

School of Food Science and Engineering, South China University of Technology, Guangzhou 510644, China.

The application of chitosan nanofibers in biological tissue-engineering materials has attracted wide attention. A novel and organic solvent-free method was developed for the fabrication of rootlike chitosan nanofibers (CSNFs) with diameters of 40-250 nm. This method includes three-step mechanical processing of swelling-beating-centrifugation or swelling-beating-homogenization. The obtained nanofibers showed high yields (>95%) and positive specific surface charges (up to +375 μeq/g) and could be uniformly dispersed in the aqueous phase. The unique fiber shape and the good length-to-diameter ratio of CSNFs endowed chitosan nanofiber paper (CSNFP) products with excellent mechanical properties, and the wet tensile strength of the CSNFPs was nearly five times higher than common chitosan films. In addition, the calvaria-derived preosteoblastic cells exhibited a higher adherence efficiency and proliferation on CSNFP than on chitosan films. The chitosan nanofiber scaffold products also benefited the attachment of preosteoblastic cells and allowed them to grow in three dimensions. This method has significant industrial potential for the industrialization of chitosan nanofibers, which may have broad applications in various biomaterials.
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http://dx.doi.org/10.1021/acsami.0c21796DOI Listing
March 2021

Assessment of heavy metal content, distribution, and sources in Nansi Lake sediments, China.

Environ Sci Pollut Res Int 2021 Jun 16;28(24):30929-30942. Epub 2021 Feb 16.

Chinese Research Academy of Environmental Sciences, Beijing, 100021, China.

Much attention has been paid to the heavy metal contamination of lake sediments in rapidly developing regions. In this study, heavy metal (Cd, Cr, Co, Ni, Mn, Pb, As, Cu, and Zn) concentrations in sediment surface samples and cores from the Nansi Lake were investigated to ascertain the potential sources and environmental risks of heavy metals. The average concentration of heavy metals was 0.16-16.04 times background concentrations. The enrichment factor, Tomlinson pollution load index, geo accumulation index, positive definite matrix factor analysis (PMF), and potential ecological risk index were used to assess heavy metal concentrations and explore the evolution of heavy metal sources, and result indicated that Cd reached moderate pollution levels, which is the most polluted heavy metal in the history and present, while the remaining heavy metals are at low or no pollution levels. The contribution of Cd to RI exceeded 76%, which is the decisive factor in the ecological risk of Nansi Lake. The result of ecological risk showed that the risk level for most of Nansi Lake is medium, and some areas of Zhaoyang Lake and Weishan Lake reach high levels. The PMF results showed that there are four main factors influencing heavy metal concentrations in Nansi Lake sediments, including industrial sources, fertilizers, and herbicides used in agricultural production, traffic-related emissions, and mineral mining. Among these factors, industrial and mineral mining sources were found to be the most important, and the highest contribution rate occurred in the -10cm (1960s). Although the contribution of fertilizers and herbicides is lower than that of other sources, increasing trend should be a warning sign that Cd has reached a high ecological risk level in Nansi Lake sediments.
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http://dx.doi.org/10.1007/s11356-021-12729-9DOI Listing
June 2021

Tibial component coverage affects tibial bone resorption and patient-reported outcome measures for patients following total knee arthroplasty.

J Orthop Surg Res 2021 Feb 12;16(1):134. Epub 2021 Feb 12.

Department of Orthopedics, Huashan Hospital, Fudan University, 12, Wulumuqi Rd., Jing'an District, Shanghai, China.

Purpose: The aim of this study is to investigate the prognostic value of tibial component coverage (over-hang and under-hang) and the alignment of total knee arthroplasty (TKA) components 1 week after surgery. We select patient-reported outcome measures (PROMS) (the Knee Society score (KSS score) and the Western Ontario and McMaster Universities Osteoarthritis Index-pain score (WOMAC pain score)) and tibial bone resorption (TBR) 2 years after surgery as the end points.

Methods: The study retrospectively analyzed 109 patients undergoing TKA (fixed-bearing prosthesis with asymmetrical tibial tray) from January 2014 to December 2017 in Huashan Hospital. By using standard long-leg X-rays, anteroposterior (AP) and lateral X-rays of the knee, tibial component coverage (under-hang or over-hang), AP tibial-femoral anatomical angle (AP-TFA), AP femoral angle (AP-FA), AP tibial angle (AP-TA), and lateral tibial angle (L-TA) were measured at 1 week after surgery, while TBR was measured through postoperative 1-week and 2-year AP and lateral radiographs of the knee on three sides (medial side, lateral side on AP radiograph, and anterior side on lateral radiograph). The Pearson correlation analysis, simple linear regression, multiple linear regression, the Student's t test, and one-way ANOVA together with Tukey's post hoc test (or Games-Howell post hoc test) were used in the analyses.

Results: Tibial under-hang was more likely to appear in our patients following TKA (42%, medially, 39%, laterally, and 25%, anteriorly). In multivariate linear regression analysis of TBR, tibial under-hang (negative value) 1 week after surgery was positively correlated with TBR 2 years later on the medial (p = 0.003) and lateral (p = 0.026) side. Tibial over-hang (positive value) 1 week after surgery on the medial side was found negatively related with KSS score (p = 0.004) and positively related with WOMAC pain score (p = 0.036) 2 years later in multivariate linear regression analysis of PROMS. Both scores were better in the anatomically sized group than in the mild over-hang group (or severe over-hang) (p < 0.001). However, no significant relationship was found between the alignment of TKA components at 1 week after surgery and the end points (TBR and PROMS) 2 years later.

Conclusion: Under-hang of the tibial component on both the medial and lateral sides can increase the risk of TBR 2 years later. Over-hang of tibial component on the medial side decreases the PROMS (KSS score and WOMAC pain score) 2 years later. An appropriate size of tibial component during TKA is extremely important for patient's prognosis, while the alignment of components might not be as important.
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http://dx.doi.org/10.1186/s13018-021-02250-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7881541PMC
February 2021

Nonanatomical Reduction of Femoral Neck Fractures in Young Patients (≤65 Years Old) with Internal Fixation Using Three Parallel Cannulated Screws.

Biomed Res Int 2021 4;2021:3069129. Epub 2021 Jan 4.

Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai 200040, China.

Purpose: The study is aimed at investigating the association between different reduction classifications (anatomic reduction, positive buttress position reduction, and negative buttress position reduction) and two end points (complications and reoperations).

Methods: The study retrospectively analyzed 110 patients undergoing internal fixation with three parallel cannulated screws from January 2012 to January 2019 in Huashan Hospital. Based on the principles of the "Gotfried reduction," all enrolled patients were divided into three groups: anatomic reduction, positive buttress position reduction, and negative buttress position reduction intraoperatively or immediately after surgery. Clinical characteristics including age, sex, side, Garden classification, Pauwels classification, fracture level, reduction classification, Garden alignment index angles, cortical thickness index (CTI), tip-caput distance (TCD), angle of the inferior screw, and the two ending points (complications and reoperations) were included in the statistical analysis. The Mann-Whitney -test, the chi-square test, Fisher's exact test, and multiple logistic regression analysis were used in the study.

Results: Of the 110 patients included in our study, the mean ± standard deviation (SD) of age was 51.4 ± 10.4 years; 41 patients showed anatomic reduction, 35 patients showed positive buttress position reduction, and 34 patients showed negative buttress position reduction. For the outcomes, 24 patients (anatomic reduction: 6 [14.6%]; positive buttress position reduction: 5 [14.3%]; negative buttress position reduction: 13 [38.2%]) had complications, while 18 patients (anatomic reduction: 5 [12.2%]; positive buttress position reduction: 3 [8.6%]; negative buttress position reduction: 10 [29.4%]) underwent reoperations after surgery. In the multivariate logistic regression analysis of complications, negative buttress position reduction (negative buttress position reduction vs. anatomic reduction, OR = 4.309, 95%CI = 1.137 to 16.322, and = 0.032) was found to be correlated with higher risk of complications. The same variable (negative buttress position reduction vs. anatomic reduction, OR = 5.744, 95%CI = 1.177 to 28.042, and = 0.031) was also identified as risk factor in the multivariate logistic regression analysis of reoperations. However, no significant difference between positive reduction and anatomical reduction was investigated in the analysis of risk factors for complications, not reoperations.

Conclusion: Positive buttress position reduction of femoral neck fractures in young patients showed a similar incidence of complications and reoperations compared with those of anatomic reduction. For irreversible femoral neck fractures, if positive buttress position reduction has been achieved intraoperatively, it is not necessary to pursue anatomical reduction; however, negative reduction needs to be avoided.
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http://dx.doi.org/10.1155/2021/3069129DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7801101PMC
May 2021

Predictive values of the postoperative neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and lymphocyte-to-monocyte ratio for the diagnosis of early periprosthetic joint infections: a preliminary study.

J Orthop Surg Res 2020 Nov 30;15(1):571. Epub 2020 Nov 30.

Department of Orthopedics, Huashan Hospital, Fudan University, No.12 Middle Urumqi Road, Shanghai, 200040, China.

Background: Several studies have been conducted to report diagnostic values of the neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and lymphocyte-to-monocyte ratio (LMR) in the many diseases, such as oncological, inflammatory, and some infectious diseases. However, the predictive value of these laboratory parameters for early periprosthetic joint infections (PJIs) has not yet been reported. The aim of this study was to determine predictive values of the postoperative NLR, PLR, and LMR for the diagnosis of PJIs.

Methods: In this retrospective study, 104 patients (26 early PJI cases and 78 non-PJI cases) who underwent total joint arthroplasty were enrolled in this study. All the patients were then categorized into two groups: PJI group, patients with the diagnosis of PJI (26 patients; 14 males, 12 females; mean age = 65.47 ± 10.23 age range = 51-81 ) and non-PJI group, patients without PJI (78 patients; 40 males, 38 females; mean age = 62.15 ± 9.33, age range = 41-92). We defined "suspected time" as the time that any abnormal symptoms or signs occurred, including fever, local swelling, or redness around the surgical site between 2 and 4 weeks after surgery and before the diagnosis. Suspected time and laboratory parameters, including NLR, PLR, LMR, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP), were compared between both groups. The trends of postoperative NLR, LMR, PLR, CRP, and ESR were also reviewed. The predictive ability of these parameters at the suspected time for early PJI was evaluated by multivariate analysis and receiver operating characteristic (ROC) curve analysis.

Results: NLR, PLR, and LMR returned to preoperative levels within 2 weeks after surgery in the two groups. In the PJI group, NLR and PLR were significantly increased during the incubation period of infection or infection, and LMR was significantly reduced, although 61.5% (16/26) of the patients had normal white blood cells. Interestingly, ESR and CRP were still relatively high 2 weeks after surgery and were not different between the two groups before infection started (p = 0.12 and 0.4, respectively). NLR and PLR were significantly correlated with early PJI (Odds ratios for NLR and PLR = 88.36 and 1.12, respectively; p values for NLR and PLR = 0.005 and 0.01, respectively). NLR had great predictive ability for the diagnosis of early PJI, with a cut-off value of 2.77 (sensitivity = 84.6%, specificity = 89.7%, 95% CI = 0.86-0.97).

Conclusions: ESR and CRP seem not to be sensitive for the diagnosis of early PJI due to their persistently high levels after arthroplasty. The postoperative NLR at the suspected time may have a great ability to predict early PJI.
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http://dx.doi.org/10.1186/s13018-020-02107-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7708199PMC
November 2020

Predictive value of adipose to muscle area ratio based on MRI at knee joint for postoperative functional outcomes in elderly osteoarthritis patients following total knee arthroplasty.

J Orthop Surg Res 2020 Oct 27;15(1):494. Epub 2020 Oct 27.

Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai, 200040, China.

Background: The current research used a new index-adipose to muscle area ratio (AMR)-to measure fatness compared with body mass index (BMI) in elderly osteoarthritis (OA) patients following total knee arthroplasty. Our study aimed to test the relationship between the two indexes (AMR and BMI) and to examine whether AMR was a predictive factor of patient-reported outcome measures (PROMS) for elderly OA patients following total knee arthroplasty (TKA).

Methods: The retrospective data of 78 OA patients (older than 60 years) following TKA was included in our study. Clinical features of patients included age, BMI, sex, AMR, side of the implant, time of follow-up, complications, the Knee Society Score (KSS score), and the Hospital for Special Surgery knee score (HSS score). The area of adipose tissue and muscle tissue was measured on the cross section (supra-patella, midline of the patella, joint line of the knee) of the knee magnetic resonance imaging (MRI). AMR was calculated as the average of adipose to muscle area ratio at the three levels. The Pearson correlation analysis, simple linear regression, and multiple linear regression were used to study the relationship between BMI, AMR, and PROMS (KSS total-post score and HSS-post score) in the study.

Results: Of all patients, the mean (± standard deviations (SD)) of age was 67.78 ± 4.91 years. For BMI and AMR, the mean (± SD) were 26.90 ± 2.11 and 2.36 ± 0.69, respectively. In Pearson correlation analysis, BMI had a good correlation with AMR (r = 0.56, p = 0.000), and AMR (r = - 0.37, p = 0.001, HSS-post score; r = - 0.43, p = 0.000, KSS total-post score) had better correlations with PROMS postoperatively compared with BMI (r = - 0.27, p = 0.019, HSS-post score; r = - 0.33, p = 0.003, KSS total-post score). In multivariate linear regression analysis, AMR was negatively correlated with KSS total-post score as well as HSS-post score, while BMI was not. As for patients with complications, AMR values were between the 3rd quartile and 4th quartile of the AMR value in the entire study cohort.

Conclusions: In this study, the new obesity evaluation indicator-AMR, which was well related with BMI, was found to be a predictor of PROMS (KSS total-post score and HSS-post score) in elderly OA patients following TKA.
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http://dx.doi.org/10.1186/s13018-020-02014-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7590798PMC
October 2020

A silk-based high impact composite for the core decompression of the femoral head.

J Mater Chem B 2020 11 6;8(42):9734-9743. Epub 2020 Oct 6.

Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai 200040, P. R. China.

Core decompression of the femoral head is a recommended head-conserving strategy for early-stage osteonecrosis of the femoral head. However, no ideal filling material has been found so far. In this study, we fabricated a "solid core-porous coating" composite scaffold, which is a silk fibroin/hydroxypropyl methylcellulose (SF/HPMC) scaffold, by a "two-step" process. The solid core scaffold possesses a sufficient compression modulus (860 MPa) for support, while the porous coating scaffold with controllable pore size and porosity provides a suitable microenvironment for the osteoblast cell to adhere and proliferate. Moreover, the porous coating scaffold was mineralized by adding different contents of hydroxyapatite crystal to further enhance its osteoinductivity, according to the simulated body fluid (SBF) biomineralization assay. To demonstrate the biocompatibility and osteoinductivity of such composite scaffolds, a series of in vitro experiments were performed, indicating the MC3T3-E1 pre-osteoblast cells grew and differentiated well on the mineralized porous coating scaffolds. The mechanical testing results also proved that the mechanical property of the solid core scaffold varied (230-1600 MPa) with different solid contents of SF/HPMC, as expected. Furthermore, the rabbit femoral head core decompression model was adopted and confirmed the excellent mechanical performance of the solid core scaffolds, as well as the satisfied osteoinductivity of the porous coating scaffold, by inserting the composite scaffolds into the bone tunnel in vivo. All of the preliminary results implied that the novel biodegradable composite scaffold has an outstanding prospective for the clinical use of core decompression of the femoral head.
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http://dx.doi.org/10.1039/d0tb01543aDOI Listing
November 2020

Combined culture experiment of mouse bone marrow mesenchymal stem cells and bioceramic scaffolds.

Exp Ther Med 2020 Nov 27;20(5):19. Epub 2020 Aug 27.

Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China.

Articular cartilage injuries are common orthopedic conditions that severely affect the quality of life of patients. Tissue engineering can facilitate cartilage repair and the key points involve scaffolding and seed cell selection. Pre-experiments found a range of microstructures of bioceramic scaffolds suitable for chondrocyte adhesion and proliferation, and maintaining chondrocyte phenotype. Three-dimensional cultures of bone marrow mesenchymal stem cell (BMSC) scaffolds were implanted into mice. According to the shape of the bioceramic scaffolds and the implantation time , RNA sequencing was performed on the removed scaffolds to explore the molecular mechanism. The bone plate culture can induce differentiation of chondrocytes, making culture different to that produced . Implantation of scaffolds increases the expression of bone-related genes. The ceramic rod-like material was found to be superior to the disc shape, and the bone repair effect was more marked with longer implantation times. Gene Ontology analysis revealed that 'cell chemotaxis', 'negative regulation of ossification' and 'bone development' pathways were involved in recovery. It was further confirmed that BMSCs were suitable as seed cells for cartilage tissue engineering, and that the β-tricalcium phosphate scaffold maybe ideal as cartilage tissue engineering scaffold material. The present research provided new insights into the molecular mechanism of cartilage repair by BMSCs and bioceramic scaffolds. Bioinformatics analysis revealed that AMMECR1L-like protein, tumor necrosis factor-induced protein 2, inhibitor of nuclear factor-B kinase subunit and protein kinase C type and 'negative regulation of ossification' and 'bone development' pathways may be involved in osteoblast maturation and bone regeneration.
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http://dx.doi.org/10.3892/etm.2020.9147DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7471870PMC
November 2020

Reset Observer-Based Zeno-Free Dynamic Event-Triggered Control Approach to Consensus of Multiagent Systems With Disturbances.

IEEE Trans Cybern 2020 Jul 13;PP. Epub 2020 Jul 13.

In this article, we investigate the observer-based event-triggered consensus problem of multiagent systems with disturbances. A reset observer consisting of a linear observer and reset element is proposed, the reset element endows the reset observer the ability to improve transient estimation performance compared with traditional linear observers. A hybrid dynamic event-triggering mechanism (ETM) is proposed, in which an internal timer variable is introduced to enforce a lower bound for the triggering intervals such that Zeno-free triggering can be guaranteed even in the presence of disturbances. Then, in order to describe the closed-loop system with both flow dynamics and jump dynamics, a hybrid model is constructed, based on which the Lyapunov-based consensus analysis and dynamic ETM design results are presented. In contrast with linear observer-based consensus protocols and the existing dynamic ETMs, the system performance can be improved and continuous communication between neighboring agents is not needed. Finally, a simulation example is provided to show the effectiveness of the proposed methods.
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http://dx.doi.org/10.1109/TCYB.2020.3003330DOI Listing
July 2020

One-pot biocatalytic synthesis and antioxidant activities of highly lipophilic naringin derivatives by using bi-functional whole-cells.

Food Res Int 2020 10 6;136:109291. Epub 2020 May 6.

School of Food Science and Engineering, South China University of Technology, Wushan Road 381, Guangzhou 510640, China. Electronic address:

Citrus peel wastes are an important renewable resource and rich in naringin, a flavonoid compound with multiple bioactivities. To cope with the low bioavailability of naringin, a new bienzyme whole-cell system was developed for bioconversion of naringin into two lipophilic derivatives. A series of naringin esters with different fatty acid chain length were successfully synthesized via cell-bound lipase catalyzed acylation, and another lipophilic product naringenin was simultaneously yielded via intracellular naringinase-catalyzed hydrolysis. The naringin esters obtained showed higher log P values and free radical-scavenging capacities against DPPH and ABTS than naringin itself. These esters also showed markedly enhanced permeability across the human intestinal Caco-2 cells. The whole-cell mediated conversion of naringin offers a two-fold advantage: naringin esters are produced as new high-valued derivatives with high lipophilicity and antioxidant activity; and the tasteless product naringenin was obtained simultaneously, which can reduce the bitterness of the total product and benefited its industrial applications.
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http://dx.doi.org/10.1016/j.foodres.2020.109291DOI Listing
October 2020

Reset Control for Consensus of Multiagent Systems with Event-Triggered Communication.

IEEE Trans Cybern 2019 Dec 20;PP. Epub 2019 Dec 20.

In the existing literature, reset control has been shown to have great potential to improve transient performance of linear systems, but reset-induced jump dynamics bring difficulties for stability analysis, especially under the network environment. In this article, we apply reset control to the consensus of multiagent systems (MASs) with event-triggered communication, and a novel reset mechanism (RM) and a hybrid event-triggering mechanism (ETM) are proposed with guaranteed Zeno-freeness. The state space is decomposed into multiple flow sets and jump sets according to the RM and ETM, and a hybrid model of the MASs is constructed such that the reset induced and event-trigger induced jump dynamics can be handled in a unified framework. Based on the hybrid model, a novel hybrid systems framework is presented for consensus analysis and co-design of RM and ETM. Finally, the proposed design is verified with a simulation example.
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http://dx.doi.org/10.1109/TCYB.2019.2956491DOI Listing
December 2019

Biocatalytic Synthesis of Lipophilic Baicalin Derivatives as Antimicrobial Agents.

J Agric Food Chem 2019 Oct 8;67(42):11684-11693. Epub 2019 Oct 8.

Enzymatic acylation is commonly used to increase the lipophilicity of flavonoids. However, the absence of primary hydroxyl groups makes it challenging to acylate baicalin using traditional acylation methods. In this study, an enzymatic esterification strategy was developed to introduce fatty-acid chains into baicalin at its carboxyl group, hence successfully synthesizing a new series of baicalin ester derivatives in nonaqueous media. Under the optimal reaction conditions, up to 95% conversion of baicalin was achieved. Antimicrobial evaluation of the baicalin ester derivatives indicated a corresponding increase to that of  log  values, with a cutoff effect at  log  = 5.2. Baicalin ester derivatives with  log  values of 4.9-5.2 exhibited the most potent antimicrobial activity. Interestingly, the introduction of medium-length fatty alcohol chains not only increased lipophilicity but also endowed them with membrane-disrupting properties. This study, therefore, provides an understanding of the esterification of flavonoid glycosides and a prospective application of the ester derivatives.
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http://dx.doi.org/10.1021/acs.jafc.9b04667DOI Listing
October 2019

Changes in Centrality Frequency of the Default Mode Network in Individuals With Subjective Cognitive Decline.

Front Aging Neurosci 2019 20;11:118. Epub 2019 Jun 20.

School of Life Science, Beijing Institute of Technology, Beijing, China.

Despite subjective cognitive decline (SCD), a preclinical stage of Alzheimer's disease (AD), being widely studied in recent years, studies on centrality frequency in individuals with SCD are lacking. This study aimed to investigate the differences in centrality frequency between individuals with SCD and normal controls (NCs). Forty individuals with SCD and 53 well-matched NCs underwent a resting-state functional magnetic resonance imaging scan. We assessed individual dynamic functional connectivity using sliding window correlations. In each time window, brain regions with a high degree centrality were defined as hubs. Across the entire time window, the proportion of time that the hub appeared was characterized as centrality frequency. The centrality frequency correlated with cognitive performance differently in individuals with SCD and NCs. Our results revealed that in individuals with SCD, compared with NCs, correlations between centrality frequency of the anterior cortical regions and cognitive performance decreased (79.2% for NCs and 43.5% for individuals with SCD). In contrast, correlations between centrality frequency of the posterior cortical regions and cognitive performance increased in SCD individuals compared with NCs (20.8% for NCs and 56.5% for individuals with SCD). Moreover, the changes mainly focused on the anterior (93.3% for NCs and 45.5% for individuals with SCD) and posterior (6.7% for NCs and 54.5% for individuals with SCD) regions associated with the default mode network (DMN). In addition, we used absolute thresholds (correlation efficient = 0.2, 0.25) and proportional thresholds (sparsity = 0.2, 0.25) to verify the results. Dynamic results are relative stable at absolute thresholds while static results are relative stable at proportional thresholds. Converging findings provide a new framework for the detection of the changes occurring in individuals with SCD via centrality frequency of the DMN.
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http://dx.doi.org/10.3389/fnagi.2019.00118DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6595963PMC
June 2019

Distributed Event-Triggered Consensus of Multiagent Systems With Communication Delays: A Hybrid System Approach.

IEEE Trans Cybern 2020 Jul 3;50(7):3169-3181. Epub 2019 May 3.

This paper investigates the leader-following consensus problem for multiagent systems (MASs) with communication delays. A novel hybrid event-triggered control scheme is developed and a hybrid system approach is proposed to design the event-triggering condition. Meanwhile, by means of temporal regularization, a strictly positive lower bound on the interevent times can be guaranteed, that is, Zeno-freeness can be guaranteed. The MASs are first described as a closed-loop system with both flow dynamics and jump dynamics, where the jump dynamics is induced from the triggering events and communication delays. Then, a hybrid model of the MASs is constructed under a hybrid systems framework. Based on this hybrid model, how to construct the Lyapunov function is given and the event-triggering condition design is also developed, such that the asymptotic consensus is achieved. Finally, an example is provided to show the effectiveness of the proposed approach.
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http://dx.doi.org/10.1109/TCYB.2019.2912403DOI Listing
July 2020

Association of hepatitis B infection with high-risk complications in total joint arthroplasty.

BMC Musculoskelet Disord 2019 Apr 11;20(1):163. Epub 2019 Apr 11.

Division of Orthopaedic Surgery, Huashan Hospital, Fudan University, Shanghai, 200040, China.

Background: An increasing number of patients with hepatitis B virus (HBV) infection are undergoing total joint arthroplasty (TJA) surgery in China. Less attention is provided to the special populations and the purpose of this study is to assess the effect of HBV infection on the prognosis TJAs.

Methods: We retrospectively reviewed patients who underwent elective primary hip and knee arthroplasties in Shanghai Huashan Hospital from 2013 to 2016. Non-hepatitis B cohort was built to match the case cohort to identify whether HBV infection was a risk factor associated with postoperative complications. A total number of 196 patients who underwent primary TJAs were involved in the study, including 49 patients with hepatitis B and 147 non-hepatitis B subjects.

Results: Among all the patients with TJAs, 5.5% of patients were infected with HBV for the first time. The incidence rate of complications in patients after arthroplasty with hepatitis B infection was significantly higher than that in patients without hepatitis B (10.2% compared to 4.7%, P < 0.01). Surgical related complications (6.1% compared to 3.4%) and general medical complications (4.1% compared to 1.3%) were higher than those in non-B hepatitis group. Compared with non-B hepatitis group, the overall risk of hepatitis B infection increased by 25% (95% CI, 1.04-1.46; p < 0.01). Similar results were obtained for medical and surgical complications. HBV infection presented a 31% increased risk (95% CI, 1.02-1.62; p < 0.01) for medical complication and an 18% increased risk (95% CI, 1.10-1.26; p < 0.01) for surgical complication. No statistical difference was found between the surgical methods and sex. However, a significant difference of C-reactive protein (CRP) level was found between HBV infection group and the matched non-infected group (P < 0.01).

Conclusion: This is the first study to investigate the risk of perioperative complications of hepatitis B in Chinese TJAs patients. In consideration of the large population of HBV infection in China, more attention and medical care should be provided to patients with HBV infection who need to undergo TJA operation.
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http://dx.doi.org/10.1186/s12891-019-2535-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6458739PMC
April 2019

The prognostic significance of the neutrophil-to-lymphocyte ratio and the platelet-to-lymphocyte ratio in giant cell tumor of the extremities.

BMC Cancer 2019 Apr 8;19(1):329. Epub 2019 Apr 8.

Department of Orthopaedic Surgery, Huashan Hospital, Fudan University, No. 12 Wulumuqi Road(M), Shanghai, 200040, China.

Background: In this study, the influence of the neutrophil-to-lymphocyte ratio (NLR) and the platelet-to-lymphocyte ratio (PLR) on the prognosis of giant cell tumor (GCT) of the extremities were investigated.

Methods: The clinical parameters of 163 patients who were diagnosed with GCT of the extremities between July 2008 and January 2018 were retrospectively analyzed. Optimal cutoff values of NLR and PLR were determined using receiver operating characteristic (ROC) analysis. According to optimal cutoff values, patients were divided into high NLR and low NLR groups or high PLR and low PLR groups. Kaplan-Meier and log-rank methods were used to compare the recurrence-free survival (RFS) between the high and low NLR groups, and between the high and low PLR groups. Univariate analysis was performed to determine the influence of age, gender, neutrophil count, lymphocyte count, platelet count, white blood cell count, tumor size, surgical approach and Campanacci stage on the prognosis of giant cell tumor of bone. The main predictors of RFS were determined by Cox multivariate regression analysis.

Results: The optimal cutoff value of NLR in giant cell tumor of the extremities was 2.32, which was used to classify patients into high and low NLR groups. The optimal cutoff value of PLR was 116.81, and was used to classify patients into high and low PLR groups. Campanacci stage, tumor maximum diameter, alkaline phosphatase, and C-reactive protein (CRP) were significantly associated with the high NLR and PLR. Cox multivariate regression analysis revealed that the Campanacci stage (HR = 3.28, 95% CI: 1.24~8.69) and NLR (HR = 4.18, 95% CI: 1.83~9.57) were independent prognostic factors for giant cell tumor of the extremities.

Conclusion: As a novel inflammatory index, NLR has some predictive power for the prognosis of patients with giant cell tumor of the extremities.
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http://dx.doi.org/10.1186/s12885-019-5511-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6454707PMC
April 2019

Whole-Cell Catalytic Synthesis of Puerarin Monoesters and Analysis of Their Antioxidant Activities.

J Agric Food Chem 2019 Jan 31;67(1):299-307. Epub 2018 Dec 31.

School of Food Sciences and Engineering , South China University of Technology , Wushan Road 381 , Guangzhou 510641 , People's Republic of China.

Puerarin, an important isoflavonoid from the edible root of Pueraria lobata, shows multiple bioactivities but suffers from low bioavailability. In this study, a new whole-cell catalytic method for acylation modification of puerarin was developed. Among the 12 strains tested, Aspergillus oryzae showed the highest catalytic activity and selectively catalyzed acylation of puerarin at the 6″-hydroxyl group. The organic solvents used significantly influenced the catalytic efficiency of the cells. In the green solvent 2-methyltetrahydrofuran, the reaction showed high substrate conversion (92.5%) and regioselectivity (95.8%), with results similar to those with tetrahydrofuran (94.2% and 98.5%, respectively) under optimal conditions. The monoester products showed higher liposolubility in comparison to puerarin, and those with C3-C8 fatty acid chain lengths showed evidently improved antioxidant activity toward erythrocyte hemolysis. Considering the operational stability of the cells and efficiency of the scaled-up reactions, this method is efficient and cost effective, with promising applications in the health food industry.
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http://dx.doi.org/10.1021/acs.jafc.8b05805DOI Listing
January 2019

Analysis of the association between CDH2 gene polymorphism and osteoarthritis risk.

Med Sci (Paris) 2018 Oct 7;34 Focus issue F1:105-112. Epub 2018 Nov 7.

Division of orthopaedic surgery, Huashan Hospital, Fudan University, Shanghai, China, 400040 Shanghai, China.

Objective: to define the cadherin 2 (CDH2) gene polymorphism in Chinese osteoarthritis and control populations and to explore the correlation between CDH2 gene polymorphism and the risk of osteoarthritis.

Method: a total of 476 patients with osteoarthritis were collected and 380 control subjects were included in the study. Clinical data such as gender, age and functional score were collected. The blood and tissue samples were collected and genotyped by PCR. Data analysis was performed using SPSS 19.0, Hapioview 4.2 and SNPstats softwares.

Results: the association of rs11083271 and osteoarthritis was initially validated in this study population (P = 0.016, OR = 1.43 (1.07- 1.93)]. The risk of OA was significantly higher in heterozygous T/C than in homozygous T/T and C/C in rs11083271. By adjusting the age, according to gender stratification analysis, the heterozygous T/C genotype in rs11083271 significantly increased the risk of OA incidence in males [p = 0.011, 3.40 (1.55-7.43)]. The remaining rs sites were not significantly associated with OA. Notably, the association of rs11564299 with OA, regardless of genotyping, gene frequency and RNA expression levels in the study population, was not confirmed.

Conclusion: in this study, we have analyzed the association between CDH2 gene polymorphism and OA in Chinese population. We found that rs11083271 heterozygous T/C genotype significantly increases the risk of OA and the severity of the disease. By contrast, the rs11564299 locus and OA have no significant correlation in the Chinese population. The role of rs11083271 in the regulation of CDH2 expression levels and the mechanisms by which it impacts OA remain to be further studied.
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http://dx.doi.org/10.1051/medsci/201834f118DOI Listing
October 2018

Computational QSAR model combined molecular descriptors and fingerprints to predict HDAC1 inhibitors.

Med Sci (Paris) 2018 Oct 7;34 Focus issue F1:52-58. Epub 2018 Nov 7.

Division of Orthopaedic Surgery, Huashan Hospital, Fudan University, Shanghai, China.

The dynamic balance between acetylation and deacetylation of histones plays a crucial role in the epigenetic regulation of gene expression. It is equilibrated by two families of enzymes: histone acetyltransferases and histone deacetylases (HDACs). HDACs repress transcription by regulating the conformation of the higher-order chromatin structure. HDAC inhibitors have recently become a class of chemical agents for potential treatment of the abnormal chromatin remodeling process involved in certain cancers. In this study, we constructed a large dataset to predict the activity value of HDAC1 inhibitors. Each compound was represented with seven fingerprints, and computational models were subsequently developed to predict HDAC1 inhibitors via five machine learning methods. These methods include naïve Bayes, κ-nearest neighbor, C4.5 decision tree, random forest, and support vector machine (SVM) algorithms. The best predicting model was CDK fingerprint with SVM, which exhibited an accuracy of 0.89. This model also performed best in five-fold cross-validation. Some representative substructure alerts responsible for HDAC1 inhibitors were identified by using MoSS in KNIME, which could facilitate the identification of HDAC1 inhibitors.
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http://dx.doi.org/10.1051/medsci/201834f110DOI Listing
October 2018

The predictive value of preoperative neutrophil-lymphocyte ratio (NLR) on the recurrence of the local pigmented villonodular synovitis of the knee joint.

BMC Musculoskelet Disord 2018 Sep 19;19(1):339. Epub 2018 Sep 19.

Division of orthopaedic surgery, Huashan Hospital, Fudan University, Shanghai, 200040, China.

Background: To explore and evaluate the predictive value of preoperative Neutrophil-lymphocyte ratio (NLR) on the recurrence of pigmented villonodular synovitis (PVNS) of the knee joint treated by arthroscopic surgery combining local radiotherapy.

Methods: Sixty pathological-proven PVNS cases of the knee joint in our department from April 2006 to March 2017 were included. All of them are treated by arthroscopic synovectomy combined with adjuvant radiotherapy. The pre-operative hematological indexes such as c-reactive protein (CRP), erythrocyte sedimentation rate (ESR), NLR, Platelet-lymphocyte ratio (PLR) and Lymphocyte-monocyte ratio (LMR) were collected retrospectively and their relationship with postoperative recurrence was analyzed by using univariate and multivariate analysis, the receiver operating characteristic curves (ROC curve), the Kappa correspondence test and the Mc Nemar Chi-square test.

Results: All 60 patients were followed up for a median of 52.8 months (7-138 months) and the recurrence rate is about 23.3% (14/60). There is a significant difference in NLR between the recurrent and non-recurrent group (P = 0.002). It had a certain correlation with postoperative recurrence (correlation coefficient r = 0.438, P = 0.001). The optimal thresholds in ROC curve were 2.42 (sensitivity 71.4%, specificity 78.3% respectively). which had predictive ability for recurrence after arthroscopic treatment.

Conclusion: The preoperative NLR is an easy and cost-effective predictor for relapse in PVNS of the knee joint after the arthroscopic surgery combined with local radiotherapy, which is of profound significance to guide clinical work.
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http://dx.doi.org/10.1186/s12891-018-2258-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6145334PMC
September 2018

Biocatalytic synthesis of acylated derivatives of troxerutin: their bioavailability and antioxidant properties in vitro.

Microb Cell Fact 2018 Aug 22;17(1):130. Epub 2018 Aug 22.

State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Wushan Road 381, Guangzhou, 510640, Guangdong, China.

Background: Flavonoid glycosides have many beneficial effects on health, but these bioactivities tend to decrease after oral administration owing to their poor lipophilicity. In this study, a facile whole-cell-based method was developed for selective preparation of monoester or diester of troxerutin, a flavonoid derivative. In addition, the bioavailabilities and antioxidant properties of troxerutin and its acylated derivatives were also investigated in cells.

Results: Pseudomonas aeruginosa and Pseudomonas stutzeri cells showed high catalytic efficiency (substrate conversion > 90%) and different preferences for troxerutin, resulting in the production of its monoester (TME) and diester (TDE), respectively. The logP values of troxerutin, TME, and TDE were - 2.04 ± 0.10, - 0.75 ± 0.08, and 1.51 ± 0.05 and their P values were 0.34 × 10 ± 0.05, 0.99 × 10 ± 0.12, and 1.54 × 10 ± 0.17 cm/s, respectively. The results of hydroxyl radical, ABTS, and ORAC assays indicated that the antiradical activities of acylated derivatives did not exceed that of troxerutin, but showed higher inhibition effects upon 2,2'-azobis(2-amidinopropane) dihydrochloride-induced erythrocyte hemolysis than that of troxerutin (P < 0.05).

Conclusion: A facile and efficient whole-cell biocatalysis method was developed to synthesize troxerutin-acylated derivatives, markedly enhancing the bioavailability and antioxidant activities of troxerutin in cells. Additionally, the mechanism underlying the observed difference in the antioxidant activities of troxerutin and its esters was ascribed to both their free radical scavenging abilities and distribution on the cell membrane surface.
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http://dx.doi.org/10.1186/s12934-018-0976-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6106897PMC
August 2018

Case report: A rare case of focal myositis presenting as Sartorius muscle contracture: A case report and review of literature.

Medicine (Baltimore) 2018 May;97(20):e10766

Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai, China.

Rationale: Focal myositis (FM) is a very rare myopathy of unknown etiology characterized by focal enlargement within one single skeletal muscle. In particular, it occurs only involving the Sartorius muscle has never been reported.

Patient Concerns: A 25-year-old man was admitted to the hospital with progressive restricted left hip joint extension, left thigh discomfort and gait disturbance for 6 years.

Diagnoses: Combining clinical manifestations with results of radiological and pathological examinations, it was consistent with the diagnosis of FM INTERVENTIONS:: The patient received a surgery under general anesthesia to release the contracted Sartorius tendon.

Outcomes: The range of motion of the patient's left hip and ipsilateral knee has significantly improved as well as the discomfort of his left thigh relieved obviously after the surgery.

Lessons: This case report is the first to report FM presenting as sartorius muscle contracture and the surgery is an alternative therapy for these patients.
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http://dx.doi.org/10.1097/MD.0000000000010766DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5976314PMC
May 2018

FGF2 and FAM201A affect the development of osteonecrosis of the femoral head after femoral neck fracture.

Gene 2018 Apr 31;652:39-47. Epub 2018 Jan 31.

Department of Orthopaedics, Huashan Hospital, Fudan University, Shanghai 200040, China.

Osteonecrosis of the femoral head (ONFH) is a common orthopedic disease associated with high disability, and femoral neck fracture (FNF) is one of the most common reasons for traumatic ONFH. This study was designed to reveal the mechanisms underlying ONFH. Using fastx_toolkit and prinseq-lite tools, quality control was conducted for the sequencing data. The differentially expressed genes (DEGs, including both mRNAs and lncRNAs) between ONFH and FNF samples were identified using the edgeR package in R, and were then subjected to enrichment analysis using the BioCloud platform. Subsequently, protein-protein interaction (PPI) networks were constructed using Cytoscape software. After the target genes of DE-lncRNAs were predicted based on Spearman's rank correlation coefficient, lncRNA-gene coexpression network was visualized using the Cytoscape software. Furthermore, functional enrichment analysis was carried out for the target genes using the clusterprofiler package in R. Additionally, the key genes were detected by quantitative real-time polymerase chain reaction (qRT-PCR). A total of 2965 DEGs were identified from the ONFH samples, including 602 DE-lncRNAs (such as downregulated FAM201A). In the PPI networks, eight upregulated genes (including FGF2, IGF1, SOX9, and COL2A1) and 11 downregulated genes were among the top 20 genes according to all of the scores, such as degree centrality, closeness centrality, and betweenness centrality scores. Functional enrichment analysis showed that IGF1, SOX9, and COL2A1 were significantly enriched during skeletal system development. Moreover, qRT-PCR experiments detected the upregulation of FGF2 and downregulation of FAM201A in ONFH samples. FGF2 and FAM201A were correlated with the development of ONFH. Besides, IGF1, SOX9, and COL2A1 might also affect the pathogenesis of ONFH.
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http://dx.doi.org/10.1016/j.gene.2018.01.090DOI Listing
April 2018

Microarray‑based screening of differentially expressed genes in glucocorticoid‑induced avascular necrosis.

Mol Med Rep 2017 Jun 5;15(6):3583-3590. Epub 2017 Apr 5.

Department of Orthopaedics, Huashan Hospital, Fudan University, Shanghai 200040, P.R. China.

The underlying mechanisms of glucocorticoid (GC)‑induced avascular necrosis of the femoral head (ANFH) have yet to be fully understood, in particular the mechanisms associated with the change of gene expression pattern. The present study aimed to identify key genes with a differential expression pattern in GC‑induced ANFH. E‑MEXP‑2751 microarray data were downloaded from the ArrayExpress database. Differentially expressed genes (DEGs) were identified in 5 femoral head samples of steroid‑induced ANFH rats compared with 5 placebo‑treated rat samples. Gene Ontology (GO) and pathway enrichment analyses were performed upon these DEGs. A total 93 DEGs (46 upregulated and 47 downregulated genes) were identified in GC‑induced ANFH samples. These DEGs were enriched in different GO terms and pathways, including chondrocyte differentiation and detection of chemical stimuli. The enrichment map revealed that skeletal system development was interconnected with several other GO terms by gene overlap. The literature mined network analysis revealed that 5 upregulated genes were associated with femoral necrosis, including parathyroid hormone receptor 1 (PTHR1), vitamin D (1,25‑Dihydroxyvitamin D3) receptor (VDR), collagen, type II, α1, proprotein convertase subtilisin/kexin type 6 and zinc finger protein 354C (ZFP354C). In addition, ZFP354C and VDR were identified to transcription factors. Furthermore, PTHR1 was revealed to interact with VDR, and α‑2‑macroglobulin (A2M) interacted with fibronectin 1 (FN1) in the PPI network. PTHR1 may be involved in GC‑induced ANFH via interacting with VDR. A2M may also be involved in the development of GC‑induced ANFH through interacting with FN1. An improved understanding of the molecular mechanisms underlying GC‑induced ANFH may provide novel targets for diagnostics and therapeutic treatment.
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http://dx.doi.org/10.3892/mmr.2017.6438DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5436162PMC
June 2017

Evaluation of the 3D finite element method using a tantalum rod for osteonecrosis of the femoral head.

Med Sci Monit 2014 Dec 6;20:2556-64. Epub 2014 Dec 6.

Department of Orthopedics, Huashan Hospital, Fudan University, Shanghai, China (mainland).

Background: The aim of this study was to contrast the collapse values of the postoperative weight-bearing areas of different tantalum rod implant positions, fibula implantation, and core decompression model and to investigate the advantages and disadvantages of tantalum rod implantation in different ranges of osteonecrosis in comparison with other methods.

Material And Methods: The 3D finite element method was used to establish the 3D finite element model of normal upper femur, 3D finite element model after tantalum rod implantation into different positions of the upper femur in different osteonecrosis ranges, and other 3D finite element models for simulating fibula implant and core decompression.

Results: The collapse values in the weight-bearing area of the femoral head of the tantalum rod implant model inside the osteonecrosis area, implant model in the middle of the osteonecrosis area, fibula implant model, and shortening implant model exhibited no statistically significant differences (p>0.05) when the osteonecrosis range was small (60°). The stress values on the artificial bone surface for the tantalum rod implant model inside the osteonecrosis area and the shortening implant model exhibited statistical significance (p<0.01).

Conclusions: Tantalum rod implantation into the osteonecrosis area can reduce the collapse values in the weight-bearing area when osteonecrosis of the femoral head (ONFH) was in a certain range, thereby obtaining better clinical effects. When ONFH was in a large range (120°), the tantalum rod implantation inside the osteonecrosis area, shortening implant or fibula implant can reduce the collapse values of the femoral head, as assessed by other methods.
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http://dx.doi.org/10.12659/MSM.890920DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4266390PMC
December 2014

Using ionic liquids in whole-cell biocatalysis for the nucleoside acylation.

Microb Cell Fact 2014 Oct 2;13:143. Epub 2014 Oct 2.

State Key lab of Pulp & Paper making Engineering, South China University of Technology, Guangzhou, 510641, China.

Background: The use of biocatalysts has become an increasingly attractive alternative to traditional chemical methods, due to the high selectivity, mild reaction conditions and environmentally-friendly processes in nonaqueous catalysis of nucleosids. However, the extensive use of organic solvents may generally suffer from sever drawbacks such as volatileness and toxicity to the environment and lower activity of the biocatalyst. Recently, ionic liquids are considered promising solvents for nonaqueous biocatalysis of polyhydroxyl compounds as ILs are environmental-friendly.

Results: In this research, we developed new IL-containing reaction systems for synthesis of long chain nucleoside ester catalyzed by Pseudomonas fluorescens whole-cells. Various ILs exerted significant but different effects on the bio-reaction. And their effects were closely related with both the anions and cations of the ILs. Use of 10% [BMI][PF6]/THF gave high reaction efficiency of arabinocytosine laurate synthesis, in which the initial rate, product yield and 5'-regioselectivity reached 2.34 mmol/L·h, 81.1% and >99%, respectively. Furthermore, SEM analysis revealed that ILs can alter the cell surface morphology, improve the permeability of cell envelopes and thus facilitate the mass transfer of substrates to the active sites of cell-bound enzymes.

Conclusion: Our research demonstrated the potential of ILs as promising reaction medium for achieving highly efficient and regioselective whole-cell catalysis.
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http://dx.doi.org/10.1186/s12934-014-0143-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4198771PMC
October 2014

Influence of organic solvents on catalytic behaviors and cell morphology of whole-cell biocatalysts for synthesis of 5'-arabinocytosine laurate.

PLoS One 2014 19;9(8):e104847. Epub 2014 Aug 19.

State Key Lab of Pulp & Paper Making Engineering, South China University of Technology, Guangzhou, China.

A whole-cell based method was developed for the regioselective synthesis of arabinocytosine laurate. Among the seven kinds of bacteria strains tested in the acylation reaction, Pseudomonas fluorescens gave the highest productivity and a higher 5'-regioselectivity than 99%. Compared with pure organic solvents, the use of organic solvent mixtures greatly promoted the yield of the whole-cell catalyzed reaction, but showed little influence on the 5'-regioselectivity. Of all the tested solvent mixtures, the best reaction result was found in isopropyl ether/pyridine followed by isopentanol/pyridine. However, the whole-cells showed much lower thermostability in isopropyl ether/pyridine than in THF-pyridine. To better understand the toxic effects of the organic solvents on P. fluorescens whole-cells and growing cells were further examined. Significant influences of organic solvents on the biomass of the cells were found, which differed depending on the type of solvents used. SEM analysis visually revealed the changes in the surface morphology of whole-cells and growing cells cultured in media containing various organic solvents, in terms of surface smoothness, bulges and changed cell sizes. Results demonstrated that organic toxicity to cell structure played an important role in whole-cell mediated catalysis.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0104847PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4138074PMC
October 2015

A two-step, one-pot enzymatic method for preparation of duck egg white protein hydrolysates with high antioxidant activity.

Appl Biochem Biotechnol 2014 Feb 24;172(3):1227-40. Epub 2013 Oct 24.

State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Wushan Road 381, Guangzhou, 510641, China.

Biocatalytic hydrolysis reactions were designed for preparation of bioactive hydrolysate of duck egg white protein (DEWP) employing two enzymes in one pot. Firstly, the fresh DEWP was thermal treated at 95 °C, for 40 min at pH 10, to effectively deactivate enzyme inhibitors thus facilitating the following two-step enzymatic hydrolysis. Compared with single-enzyme processes, the two-step enzymatic procedures showed much higher reaction efficiency. The first enzymatic step (in the presence of Alcalase or hydrolase SEEP) allowed to hydrolyze DEWP with degree of hydrolysis (DH) of 8.8-10% and soluble peptide yield (SEP) of 60.5-70.2% in a short period (4 h). The second enzymatic step (in the presence of Trypsin or Alcalase) gave a further degradation of DEWP with DH and SEP being more than 26.2% and 90.4%, respectively. The final hydrolysates exhibited high antioxidant activity in an evident DH dependent manner. The hydrolysates achieved by sequential addition of the proteinase SEEP and Alcalase at DH value 21% gave the highest antioxidant activity, which was mainly ascribed to the changes in the amino acid compositions that the contents of some key amino acids and total hydrophobic amino acids were significantly improved by the enzymatic hydrolysis.
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http://dx.doi.org/10.1007/s12010-013-0578-3DOI Listing
February 2014
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