DNA liquid crystals with AIE effect toward humidity-indicating biomaterials.

In this study, by fabricating DNA doped with tetraphenylethene-containing ammonium surfactant, the resulting solvent-free DNA ionic complex could undergo a humidity-induced phase change that could be well tracked by the fluorescence signal of the surfactant. Taking advantage of the humidity-induced change in fluorescence, the reported ionic DNA complex could accurately indicate the humidity in real time.

Influence of Oil Status on Membrane-Based Gas-Oil Separation in DGA.

Gas-oil separation by membrane stands for a promising technique in dissolved gas analysis (DGA). Since the accuracy of DGA relies on the results of gas-oil separation to a great extent, it is necessary to study the influence factor of membrane for better performance. Although plentiful studies have been conducted aiming at membrane modification to obtain better separation performance, it cannot be ignored that the conditions of oil also affect the performance of membrane much. In this work, a photoacoustic spectroscopy-based sensor for DGA, which employed membrane for gas-oil separation, was established first. By detecting the photoacoustic signal, the performance of membrane could be evaluated. Furthermore, the influences of feed velocity and pressure have on the performance of membrane were analyzed. Both simulation and experiment were employed in this work to evaluate the influences by collecting the equilibrium time of membrane under different conditions. As a result, the simulation and experiment agreed with each other well. Moreover, it was reasonable to draw the conclusion that the equilibrium time was evidently reduced with the raise of feed velocity but remained with a minimum change when pressure changed. The conclusion may serve as a reference for the application of membrane in optical sensor and DGA.

Effectiveness and safety of pegylated liposomal doxorubicin versus epirubicin as neoadjuvant or adjuvant chemotherapy for breast cancer: a real-world study.

BACKGROUND: Pegylated liposomal doxorubicin (PLD) is an improved formulation of doxorubicin with comparable effectiveness but significantly lower cardiotoxicity than conventional anthracycline. This study aimed to evaluate the real-world effectiveness and safety of PLD versus epirubicin as neoadjuvant or adjuvant treatment for breast cancer. METHODS: Clinical data of invasive breast cancer patients who received neoadjuvant or adjuvant chemotherapy with PLD or epirubicin were retrospectively collected. Propensity score matching (PSM) was performed to reduce the risk of selection bias. The molecular typing of these patients included Luminal A, Luminal B, HER2-positive, and basal-like/triple-negative. The primary outcome was pathological complete response (pCR) rate for neoadjuvant chemotherapy and 3-year disease-free survival (DFS) rate for adjuvant chemotherapy. Noninferiority was suggested if the lower limit of the 95% CI for the 3-year DFS rate difference was greater than - 10%. The secondary outcome was adverse reactions. RESULTS: A total of 1213 patients were included (neoadjuvant, n = 274; adjuvant, n = 939). pCR (ypT0/Tis ypN0) rates of patients who received neoadjuvant chemotherapy were 11.6% for the PLD group and 7.0% for the epirubicin group, but the difference was not statistically significant (P = 0.4578). The 3-year DFS rate of patients who received adjuvant chemotherapy was 94.9% [95%CI, 91.1-98.6%] for the PLD group and 95.4% [95%CI, 93.0-97.9%] for the epirubicin group (P = 0.5684). Rate difference between the two groups and its 95% CI was - 0.55 [- 5.02, 3.92]. The lower limit of the 95% CI was - 5.0% > - 10.0%, suggesting that PLD is not be inferior to epirubicin in adjuvant chemotherapy for breast cancer. The incidences of myelosuppression, decreased appetite, alopecia, gastrointestinal reactions, and cardiotoxicity were lower in the PLD group than in the epirubicin group, while the incidence of nausea was higher in the PLD group. CONCLUSIONS: In the neoadjuvant and adjuvant treatment of breast cancer, effectiveness is similar but toxicities are different between the PLD-containing regimen and epirubicin-containing regimen. Therefore, further study is warranted to explore PLD-based neoadjuvant and adjuvant chemotherapy for breast cancer.

Molecular systematics of Goodyerinae (Cranichideae, Orchidoideae, Orchidaceae) based on multiple nuclear and plastid regions.

Goodyerinae are one of the most species-rich and widespread subtribes of Orchidaceae but notorious for their taxonomic difficulty. Here, a comprehensive molecular phylogenetic study of the subtribe is presented based on two nuclear (ITS, Xdh) and five plastid (matK, psaB, rbcL, trnL, trnL-F) regions. A total of 119 species were included representing all clades recovered by previous phylogenetic analyses as well as seven outgroups. Maximum parsimony, maximum likelihood and Bayesian inference methods were used to infer the phylogenetic relationships. The results show that the Goodyerinae subdivided into three major subdivisions and six groupings: Pachyplectron, Goodyera clade (including Goodyera procera, Microchilus subclade and Goodyera subclade) and Cheirostylis clade (including Gonatostylis, Cheirostylis subclade and Ludisia subclade). Four genera, Erythrodes, Goodyera, Myrmechis and Odontochilus, are not monophyletic. The results support Odontochilus s. l. to include Myrmechis and Kuhlhasseltia. The systematic positions of Goodyera procera and two isolated genera, Herpysma and Orchipedum, are difficult to determine.

Biodegradable, Hydrogen Peroxide, and Glutathione Dual Responsive Nanoparticles for Potential Programmable Paclitaxel Release.

Reactive oxygen species (ROS) and glutathione (GSH) dual responsive nanoparticulate drug delivery systems (nano-DDSs) hold great promise to improve the therapeutic efficacy and alleviate the side effects of chemo drugs in cancer theranosis. Herein, hydrogen peroxide (H2O2) and GSH dual responsive thioketal nanoparticle (TKN) was rationally designed for paclitaxel (PTX) delivery. Compared to other stimuli-sensitive nano-DDSs, this dual responsive DDS is not only sensitive to biologically relevant H2O2 and GSH for on-demand drug release but also biodegradable into biocompatible byproducts after fulfilling its delivering task. Considering the heterogeneous redox potential gradient, the PTX loaded TKNs (PTX-TKNs) might first respond to the extracellular ROS and then to the intracellular GSH, achieving a programmable release of PTX at the tumor site. The selective toxicity of PTX-TKNs to tumor cells with high levels of ROS and GSH was verified both in vitro and in vivo.

Genome sequence and transcriptome analyses of the thermophilic zygomycete fungus Rhizomucor miehei.

BACKGROUND: The zygomycete fungi like Rhizomucor miehei have been extensively exploited for the production of various enzymes. As a thermophilic fungus, R. miehei is capable of growing at temperatures that approach the upper limits for all eukaryotes. To date, over hundreds of fungal genomes are publicly available. However, Zygomycetes have been rarely investigated both genetically and genomically. RESULTS: Here, we report the genome of R. miehei CAU432 to explore the thermostable enzymatic repertoire of this fungus. The assembled genome size is 27.6-million-base (Mb) with 10,345 predicted protein-coding genes. Even being thermophilic, the G + C contents of fungal whole genome (43.8%) and coding genes (47.4%) are less than 50%. Phylogenetically, R. miehei is more closerly related to Phycomyces blakesleeanus than to Mucor circinelloides and Rhizopus oryzae. The genome of R. miehei harbors a large number of genes encoding secreted proteases, which is consistent with the characteristics of R. miehei being a rich producer of proteases. The transcriptome profile of R. miehei showed that the genes responsible for degrading starch, glucan, protein and lipid were highly expressed. CONCLUSIONS: The genome information of R. miehei will facilitate future studies to better understand the mechanisms of fungal thermophilic adaptation and the exploring of the potential of R. miehei in industrial-scale production of thermostable enzymes. Based on the existence of a large repertoire of amylolytic, proteolytic and lipolytic genes in the genome, R. miehei has potential in the production of a variety of such enzymes.

[Advances in poly(ethylene terephthalate) hydrolases].

Plastics have brought invaluable convenience to human life since it was firstly synthesized in the last century. However, the stable polymer structure of plastics led to the continuous accumulation of plastic wastes, which poses serious threats to the ecological environment and human health. Poly(ethylene terephthalate) (PET) is the most widely produced polyester plastics. Recent researches on PET hydrolases have shown great potential of enzymatic degradation and recycling of plastics. Meanwhile, the biodegradation pathway of PET has become a reference model for the biodegradation of other plastics. This review summarizes the sources of PET hydrolases and their degradation capacity, degradation mechanism of PET by the most representative PET hydrolase-IsPETase, and recently reported highly efficient degrading enzymes through enzyme engineering. The advances of PET hydrolases may facilitate the research on the degradation mechanism of PET and further exploration and engineering of efficient PET degradation enzymes.

Ionic liquid-mediated regeneration of cellulose dramatically improves decrystallization, TEMPO-mediated oxidation and alkyl/alkenyl succinylation.

This work demonstrated a successful strategy that simple ionic liquids (ILs) mediated pretreatment could effectively reduce crystallinity of cellulose from 71 % to 46 % (by C2MIM.Cl) and 53 % (by C4MIM.Cl). The IL-mediated regeneration of cellulose greatly promoted its reactivity for TEMPO-catalyzed oxidation, which the resulting COO- density (mmol/g) increased from 2.00 for non-IL-treated cellulose to 3.23 (by C2MIM.Cl) and 3.42 (C4MIM.Cl); and degree of oxidation enhanced from 35 % to 59 % and 62 %, respectively. More significantly, the yield of oxidized cellulose increased from 4 % to 45-46 %, by 11-fold. IL-regenerated cellulose can also be directly subjected to alkyl/alkenyl succinylation without TEMPO-mediated oxidation, producing nanoparticles with properties similar to oxidized celluloses (55-74 nm in size, -70-79 mV zeta-potential and 0.23-0.26 PDI); but in a much higher overall yield (87-95 %) than IL-regeneration-coupling-TEMPO-oxidation (34-45 %). Alkyl/alkenyl succinylated TEMPO-oxidized cellulose showed 2-2.5 times higher ABTS* scavenging ability than non-oxidized cellulose; however, alkyl/alkenyl succinylation also resulted in a significant decline in Fe2+ chelating property.

Azobenzene-containing surfactant directs small features of DNA thermotropic liquid crystals via bottom-up and top-down strategies.

Compared to classical block copolymers, the self-assembly of small molecules shows an advantage in addressing small features. As a new type of solvent-free ionic complexes, azobenzene-containing DNA thermotropic liquid crystals (TLCs) form an assembly as block copolymers when using small DNA. However, the self-assembly behavior of such biomaterials has not been fully investigated. In this study, photoresponsive DNA TLCs are fabricated by employing an azobenzene-containing surfactant with double flexible chains. For these DNA TLCs, the self-assembly behavior of DNA and surfactants could be guided by the factors of the molar ratio of azobenzene-containing surfactant, dsDNA/ssDNA, and presence or absence of water, which addresses the bottom-up control on domain spacing of mesophase. Meanwhile, such DNA TLCs also gain top-down control on morphology via photoinduced phase change. This work would provide a strategy for regulating the small features of solvent-free biomaterials, facilitating the development of patterning templates based on photoresponsive biomaterials. STATEMENT OF SIGNIFICANCE: The relationship between nanostructure and function is attractive in the science of biomaterials. With biocompatibility and degradability, photoresponsive DNA materials in solutions have been widely studied in biological and medical areas, but they are still hard to obtain in a condensed state. The complex created with designed azobenzene-containing surfactants paves the way for obtaining condensed photoresponsive DNA materials. However, fine control of the small features of such biomaterials has not yet been achieved. In this study, we present a bottom-up strategy of controlling the small features of such DNA materials and, simultaneously, the top-down control of morphology via photoinduced phase change. This work provides a bi-directional approach to controlling the small features of condensed biomaterials.

Reducing plastic film mulching and optimizing agronomic management can ensure food security and reduce carbon emissions in irrigated maize areas.

Increasing crop yields to ensure food security while also reducing agriculture's environmental impacts to ensure green sustainable development are great challenges for global agriculture. Plastic film, widely used to improve crop yield, also creates plastic film residue pollution and greenhouse gas emissions that restricts the development of sustainable agriculture. So, one of those challenges is to reduce plastic film use while also ensuring food security, and thus promote green and sustainable development. A field experiment was conducted during 2017-2020 at 3 farmland areas, each with different altitudes and climate conditions, in northern Xinjiang, China. We investigated the effects on maize yield, economic returns, and greenhouse gas (GHG) emissions of plastic film mulching (PFM) versus no mulching (NM) methods in drip-irrigated maize production. We also chose maize hybrids with 3 different maturation times and used 2 planting densities to further investigate how those differences more specifically affect maize yield, economic returns, and greenhouse gas (GHG) emissions under each mulching method. We found that by using maize varieties with a utilization rate of accumulated temperature (URAT) <86.6 % with NM, and increasing the planting density by 3 plants m-2, yields and economic returns improved and GHG emissions reduced by 33.1 %, compared to those of PFM maize. The maize varieties with URATs between 88.2 % to 89.2 %, had the lowest GHG emissions. We discovered that by matching the required accumulated temperatures of various maize varieties to environmental accumulated temperatures, along with filmless and higher density planting, and modern irrigation and fertilization practices, yields increased and residual plastic film pollution and carbon emissions reduced. Therefore, these advances in agronomic management are important steps toward reducing pollution and achieving carbon peak and carbon neutrality goals.

Breaking the Limitation of Elevated Coulomb Interaction in Crystalline Carbon Nitride for Visible and Near-Infrared Light Photoactivity.

Most near-infrared (NIR) light-responsive photocatalysts inevitably suffer from low charge separation due to the elevated Coulomb interaction between electrons and holes. Here, an n-type doping strategy of alkaline earth metal ions is proposed in crystalline K+ implanted polymeric carbon nitride (KCN) for visible and NIR photoactivity. The n-type doping significantly increases the electron densities and activates the n→π* electron transitions, producing NIR light absorption. In addition, the more localized valence band (VB) and the regulation of carrier effective mass and band decomposed charge density, as well as the improved conductivity by 1-2 orders of magnitude facilitate the charge transfer and separation. The proposed n-type doping strategy improves the carrier mobility and conductivity, activates the n→π* electron transitions for NIR light absorption, and breaks the limitation of poor charge separation caused by the elevated Coulomb interaction.

Enhancing electro-transformation competency of recalcitrant Bacillus amyloliquefaciens by combining cell-wall weakening and cell-membrane fluidity disturbing.

Bacillus amyloliquefaciens has been a major workhorse for the production of a variety of commercially important enzymes and metabolites for the past decades. Some subspecies of this bacterium are recalcitrant to exogenous DNA, and transformation with plasmid DNA is usually less efficient, thereby limiting the genetic manipulation of the recalcitrant species. In this work, a methodology based on electro-transformation has been developed, in which the cells were grown in a semicomplex hypertonic medium, cell walls were weakened by adding glycine (Gly) and DL-threonine (DL-Thr), and the cell-membrane fluidity was elevated by supplementing Tween 80. After optimization of the cell-loosening recipe by response surface methodology (RSM), the transformation efficiency reached 1.13 ± 0.34 × 10(7) cfu/µg syngeneic pUB110 DNA in a low conductivity electroporation buffer. Moreover, by temporary heat inactivation of the host restriction enzyme, a transformation efficiency of 8.94 ± 0.77 × 10(5) cfu/µg DNA was achieved with xenogeneic shuttle plasmids, a 10(3)-fold increase compared to that reported previously. The optimized protocol was also applicable to other recalcitrant B. amyloliquefaciens strains used in this study. This work could shed light on the functional genomics and subsequent strain improvement of the recalcitrant Bacillus, which are difficult to be transformed using conventional methods.

Measurement of operative femoral anteversion during cementless total hip arthroplasty and influencing factors for using neck-adjustable femoral stem.

BACKGROUND: Placement of femoral stem in excessive anteversion or retroversion can cause reduced range of motion, prosthetic impingement, and dislocation. The aim of this study was to assess the operative femoral anteversion in patients treated with total hip arthroplasty (THA) and analyze the need of adjusting stem anteversion. METHODS: We retrospectively included 101 patients (126 hips) who underwent cementless THA with a manual goniometer to determine the femoral anteversion between October 2017 and December 2018. The operative femoral anteversion we measured was recorded during THA. We further divided those hips into three subgroups based on the range of operative femoral anteversion: group 1 (<10°), group 2 (10-30°), and group 3 (>30°) and compared the differences of their demographic data. Univariate and multivariate logistic regression were used to identify the influencing factors for the need of neck-adjustable femoral stem. The clinical and radiographic outcomes were also assessed. Perioperative complications were recorded. RESULTS: After THA, the Harris hip scores improved from 52.87 ± 15.30 preoperatively to 90.04 ± 3.31 at the last follow-up (p < 0.001). No implant loosening, stem subsidence, and radiolucent lines were observed on radiographs. No severe complications occurred and no components needed revision at the latest follow-up. The mean operative femoral anteversion was 14.21° ± 11.80° (range, -9 to 60°). Patients with femoral anteversion more than 30° were about 10 years younger than others. Femoral anteversion >30° was more common in patients with developmental dysplasia of the hip (DDH). There were totally 14 hips treated with the neck-adjustable femoral stem. From the univariate analysis, we can observe that female sex, diagnosis of DDH (compared with osteonecrosis), and higher operative femoral anteversion and its value >30° (compared with <10°) are associated with higher rates of using the neck-adjustable femoral stem. However, all these factors were no longer considered as independent influencing factors when mixed with other factors. CONCLUSIONS: This study highlighted the significance of operative femoral anteversion. Identification of abnormal femoral anteversion could assist in adjusting stem anteversion and reduce the risk of dislocation after THA.

Preparation and in vitro evaluation of ethosomal total alkaloids of Sophora alopecuroides loaded by a transmembrane pH-gradient method.

A novel transmembrane pH gradient active loading method to prepare alkaloids binary ethosomes was developed in this work. Using this novel method, binary ethosomes containing total alkaloids extracted from Sophora alopecuroides (TASA) were prepared successfully at the temperature below the phase transition temperature (Tc) of the phosphatidyl choline (PC). Several factors affecting this method were investigated. The qualities of the TASA binary ethosomes were characterized by the shape, particle size, and encapsulation efficiency (EE). The percutaneous absorption study of TASA binary ethosomes was performed using confocal laser scanning microscopy and Franz diffusion cells. The results showed that more than 90% sophoridine, 47% matrine, 35% sophocarpine, and 32% lemannine in TASA were entrapped within 1 h at 40°C, with an efficiency improvement of 8.87, 8.10, 7.63, and 7.78-fold than those observed in passive loading method. Transdermal experiments showed that the penetration depth and fluorescence intensity of Rhodamine B from binary ethosome prepared by pH gradient active loading method were much greater than that from binary ethosome prepared by passive loading method or hydroalcoholic solution. These results suggested transmembrane pH gradient active loading method may be an effective method to prepare alkaloids ethosomal systems at the temperatures below the Tc of PC.

In Vivo Reconstruction of the Acetabular Bone Defect by the Individualized Three-Dimensional Printed Porous Augment in a Swine Model.

METHODS: As an acetabular bone defect model created in Bama miniswine, an augment individually fabricated by 3D print technique with Ti6Al4V powders was implanted to repair the defect. Nine swine were divided into three groups, including the immediate biomechanics group, 12-week biomechanics group, and 12-week histological group. The inner structural parameters of the 3D printed porous augment were measured by scanning electron microscopy (SEM), including porosity, pore size, and trabecular diameter. The matching degree between the postoperative augment and the designed augment was assessed by CT scanning and 3D reconstruction. In addition, biomechanical properties, such as stiffness, compressive strength, and the elastic modulus of the 3D printed porous augment, were measured by means of a mechanical testing machine. Moreover, bone ingrowth and implant osseointegration were histomorphometrically assessed. RESULTS: In terms of the inner structural parameters of the 3D printed porous augment, the porosity was 55.48 ± 0.61%, pore size 319.23 ± 25.05 µm, and trabecular diameter 240.10 ± 23.50 µm. Biomechanically, the stiffness was 21464.60 ± 1091.69 N/mm, compressive strength 231.10 ± 11.77 MPa, and elastic modulus 5.35 ± 0.23 GPa, respectively. Furthermore, the matching extent between the postoperative augment and the designed one was up to 91.40 ± 2.83%. Besides, the maximal shear strength of the 3D printed augment was 929.46 ± 295.99 N immediately after implantation, whereas the strength was 1521.93 ± 98.38 N 12 weeks after surgery (p = 0.0302). The bone mineral apposition rate (µm per day) 12 weeks post operation was 3.77 ± 0.93 µm/d. The percentage bone volume of new bone was 22.30 ± 4.51% 12 weeks after surgery. CONCLUSION: The 3D printed porous Ti6Al4V augment designed in this study was well biocompatible with bone tissue, possessed proper biomechanical features, and was anatomically well matched with the defect bone. Therefore, the 3D printed porous Ti6Al4V augment possesses great potential as an alternative for individualized treatment of severe acetabular bone defects.

Clinical effects of staged joint replacement in patients with septic arthritic knee.

OBJECTIVE: To assess the clinical effect of staged joint replacement for the treatment of septic arthritic knee and the therapeutic differences between antibiotic cement beads and the tibial plateau spacer. METHODS: Twenty-three patients (24 knee joints) treated with a staged joint replacement for septic arthritis knee were retrospectively reviewed between March 2014 and April 2018. At the first stage, thorough debridement and irrigation with self-made antibiotic cement beads or tibial plateau spacer were performed. After that, systemic antibiotic treatment was followed; when the infection was surely eliminated, the second-stage TKA was performed. Knee mobility (range of motion, abbreviated to ROM) and function (HSS scores system) were evaluated before surgery, in the interval period, and after joint replacement. RESULTS: All patients finished follow-up, and the mean follow-up time was 27.3 months (12-54 months). Each group has one patient replaced with a homotypic spacer, and all patients eventually cleared the infection. None of the patients had a recurrent infection. The mobility and HSS scores of the two groups were significantly improved postoperation (p < 0.05). And there was no significant difference in the post-surgery ROM (p = 0.153) and the HSS score (p = 0.054) between the two groups. CONCLUSION: Staged joint replacement is an efficacious way for septic arthritic knees, whether tibial plateau spacer or antibiotic cement beads were used, which can effectively control infection and improve knee function.

[Experimental study of prostheses modified by three dimensions porous Ti combined bone morphogenetic proteins].

OBJECTIVE: To observe bone ingrowth of artificial femur which three dimensions (3-D) porous Ti combined bone morphogenetic proteins (BMPs) integrating on the prostheses surface in dogs. METHODS: The prostheses integrated 3-D porous Ti on the surface, which combined BMPs directly or through FG, were implanted canine. And fluorescent labeling was done at 2, 5 weeks after that, and then the prostheses with femurs were taken out in 3, 6 weeks after operation. These specimens were treated, then observed through microscopy. RESULTS: At 3 weeks, bone growing 1/2 of full thickness in 3-D porous Ti, but bone growing full thickness in 3-D porous Ti at 6 weeks. Bone formation was obviously higher at 6 weeks than at 3 weeks. CONCLUSION: The prostheses modified 3-D porous Ti can accelerate osteogenesis and improve bone formation so that mechanical interlock and integration can be come true.

Reconstruction of Severe Acetabular Bone Defect with 3D Printed Ti6Al4V Augment: A Finite Element Study.

PURPOSE: The purpose of this study was to establish the finite element analysis (FEA) model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment and TM augment and further to analyze the stress distribution and clinical safety of augments, screws, and bones. METHODS: The FEA model of acetabular bone defect reconstructed by 3D printed Ti6Al4V augment was established by the CT data of a patient with Paprosky IIIA defect. The von Mises stresses of augments, screws, and bones were analyzed by a single-legged stance loading applied in 3 increments (500 N, 2000 N, and 3000 N). RESULTS: The peak von Mises stresses under the maximal loading in the 3D printed augments, screws, and cortical bone were less than the yield strength of the corresponding component. However, the peak stress in the bone was greater than the yield strength of cancellous bone under walking or jogging loading. And under the same loading, the peak compressive and shear stresses in bone contact with TM augment were larger than these with 3D printed augment. CONCLUSIONS: The FEA results show that all the components will be intact under single-legged standing. However, partial cancellous bone contacted with 3D printed augment and screws will lose efficacy under walking or jogging load. So we recommend that patients can stand under full bearing, but can not walk or jog immediately after surgery.

[Chondrogenesis of passaged chondrocytes induced by different dynamic loads in bioreactor].

OBJECTIVE: To investigate the effect of dynamic compression and rotation motion on chondrogenesis of the 3rd passage cell-loaded three-dimensional scaffold in a joint-specific bioreactor in vitro so as to provide theoretical basis of the autologous chondrocyte transplantation in clinical practice. METHODS: Primary chondrocytes were isolated and cultured from the knee cartilage of 3-4 months old calves. The 3rd passage cells were seeded onto fibrin-polyurethane scaffolds (8 mm x 4 mm). Experiment included 5 groups: unloaded culture for 2 weeks (group A), direct load for 2 weeks (group B), unloaded culture for 4 weeks (group C), direct load for 4 weeks (group D), and unload for 2 weeks followed by load for 2 weeks (group E). The cell-scaffold was incubated in incubator (unload) or in a joint-specific bioreactor (load culture). At different time points, the samples were collected for DNA and glycosaminoglycan (GAG) quantification detect; mRNA expressions of chondrogenic marker genes such as collagen type I, collagen type II, Aggrecan, cartilage oligomeric matrix protein (COMP), and superficial zone protein (SZP) were detected by real-time quantitative PCR; and histology observations were done by toluidine blue staining and immunohistochemistry staining. RESULTS: No significant difference was found in DNA content, GAG content, and the ratio of GAG to DNA among 5 groups (P > 0.05). After load, there was a large number of GAG in the medium, and the GAG significantly increased with time (P < 0.05). The mRNA expression of collagen type I showed no significant difference among 5 groups (P > 0.05). The mRNA expression of collagen type II in group B was significantly increased when compared with group A (P < 0.01), and groups D and E were significantly higher than group C (P < 0.01); the mRNA expression of Aggrecan in groups D and E were significantly increased when compared with group C (P < 0.01), and group E was significantly higher than group D (P < 0.01); the mRNA expression of COMP in group B was significantly increased when compared with group A (P < 0.01), and group E was significantly higher than group C (P < 0.01); and the mRNA expression of SZP in group E was significantly increased when compared with groups C and D (P < 0.05). The toluidine blue staining and immunohistochemistry staining displayed that synthesis and secretion of GAG could be enhanced after load; no intensity changes of collagen type I and collagen type II were observed, but intensity enhancement of Agrrecan was seen in groups D and E. CONCLUSION: Different dynamic loads can promote chondrogenesis of the 3rd passage chondrocytes. Culture by load after unload may be the best culture for chondrogenesis, while the 3rd passage chondrocytes induced by mechanical load hold less capacity of chondrogenesis.

[Treatment of infected total knee arthroplasty with a self-made, antibiotic-loaded cement articulating spacer].

OBJECTIVE: To study the efficacy of self-made, antibiotic-loaded cement articulating spacer in the treatment of infected total knee arthroplasty. METHODS: The self-made molds were used to form the spacer during the operation. From March 2002 to March 2007, 22 patients with infected knee arthroplasty (10 males with 10 knees, 12 females with 12 knees) were treated with this kind of spacer in our center. The mean age of the patients was 59.6 years old (33 to 75 years old). The interval time between primary arthroplasty and first onset of infective syndrome was 6.7 months (1 to 14 months). The diagnosis was established by the clinical presentation,serum laboratory inflammatory markers (white blood cell count,erythrocyte sedimentation rate and C-reactive protein) and knee aspiration. The serum laboratory inflammatory markers were used to measure the systemic response to infection. Clinical and radiographic follow-up was regularly performed by HSS score system and X-ray. RESULTS: All the patients were followed, the average interval between debridement and reimplantation was 4.7 months (3 to 9 months) and the infection control rate was 100% after the implantation of spacer. The average follow-up duration after reimplantation was 29.8 months (10 to 64 months) and there was no recurrence of infection at the latest follow-up. The HSS score increased from 40.5+/-5.9 to 65.8+/-7.5 after the implantation of spacer, furthermore, the score reached 88.7+/-5.1 in average at the latest follow-up. The patient satisfaction rate was 95.3%. CONCLUSION: This self-made molds and spacers is a reliable approach for the management of infected knee arthroplasty with some virtues, such as providing a mobile and functional joint through the treatment course, decreasing the difficulty of reimplantation, avoiding of a long-term post-operative infusion and high effective for eradicating infection.