Green synthesis of silica-coated magnetic nanocarriers for simultaneous purification-immobilization of ß-1,3-xylanase.

Tailoring magnetic nanocarriers with tunable properties is of great significance for the development of multifunctional candidate materials in numerous fields. Herein, we report a one-pot biomimetic silicification-based method for the synthesis of silica-coated magnetic nanoparticles. The synthesis process was mild, low cost, and highly efficient, which took only about 21 min compared with 4.5-120 h in other literature. Then, the carriers had been characterized by VSM, SEM, TEM, XRD, FT-IR, and EDS to confirm their function. To evaluate the usefulness of the carriers, they were adopted to couple the purification and immobilization of ß-1,3-xylanase from the cell lysate in a single step with high immobilization yield (92.8 %) and high activity recovery (82.4 %). The immobilized enzyme also retained 58.4 % of the initial activity after 10 cycles and displayed good storage properties, and improved thermal stability, which would be promising in algae biomass bioconversion as well as other diverse applications.

Revealing the role of tunable amino acid residues in elastin-like polypeptides (ELPs)-mediated biomimetic silicification.

Elastin-like polypeptides (ELPs) are attractive materials for the green preparation of silica nanoparticles via biomimetic silicification. However, the critical factors affecting the ELP-mediated silicification remain unclear. Herein, the role of tunable amino acid residues of ELPs in silicification was studied using three ELPs (ELPs[V9F-40], ELPs[KV8F-40], and ELPs[K5V4F-40]) and their fusion proteins (ELPs[V9F-40]-SpyCatcher, ELPs[KV8F-40]-SpyCatcher, and ELPs[K5V4F-40]-SpyCatcher) with different contents of lysine residues. Bioinformatics methods were employed for the first time to reveal the key physicochemical parameters correlated with silicification. The specific activity of ELPs was increased with the promotion of lysine content with a high correlation coefficient (R = 0.899). Furthermore, exogenous acidic protein SpyCatcher would hinder the interactions between the silica precursors and ELPs, leading to the significantly decrease in specific activity. The isoelectric point (pI) of ELPs presented the highest correlation to silicification with a coefficient of 0.963. The charges of the ELPs [K5V4F-40] at different pH were calculated based on the sequence or structure. Interestingly, the excellent correlation between charges based on structure and specific activity was obtained. Collectively, the novel methods developed here may pave a new way for rational design of ELPs or other peptides for efficient and green preparation of silica nanomaterials for biomedicine, biocatalysis, and biosensor.

The synergism of lytic polysaccharide monooxygenases with lichenase and their co-immobilization on silica nanospheres for green conversion of lichen biomass.

Enzyme-assisted valorization of lichenan represents a green and sustainable alternative to the conventional chemical industry. The recently discovered lytic polysaccharide monooxygenases (LPMOs) are essential components of state-of-the-art enzyme cocktails for lichenin bioconversion. The LPMOs named SpyTag fused LPMOs (AST) from Chaetomium globosum was functionally expressed in E. coli and exhibited 1.25-fold synergism with lichenase, whereas AST alone produced no detectable reducing sugars. HPLC results further confirm that AST does not alter the endogenous hydrolysis mode of lichenase but rather enhances its hydrolysis efficiency by disrupting the long chain of lichenan and releasing more reducing ends. To the best of our knowledge, this was the first report on the synergistic effect of LPMOs and lichenase, which may have great synergistic potential in the conversion of lichen biomass. Furthermore, a novel strategy for the covalently immobilizing AST and lichenase on silica nanoparticles (SNPs) from the cell lysate in a single step was proposed, which exhibited high activity recovery (82.9%) and high immobilization yield (94.8%). After 12 independent runs, about 67.4 % of the initial activity of the immobilized enzymes was retained. The resulted biocatalyst systems exhibited the green and sustainable strategy in the bioconversion of lichen biomass as well as other diverse polysaccharides.

Recent Progress in Phage Therapy to Modulate Multidrug-Resistant Acinetobacter baumannii, including in Human and Poultry.

Acinetobacter baumannii is a multidrug-resistant and invasive pathogen associated with the etiopathology of both an increasing number of nosocomial infections and is of relevance to poultry production systems. Multidrug-resistant Acinetobacter baumannii has been reported in connection to severe challenges to clinical treatment, mostly due to an increased rate of resistance to carbapenems. Amid the possible strategies aiming to reduce the insurgence of antimicrobial resistance, phage therapy has gained particular importance for the treatment of bacterial infections. This review summarizes the different phage-therapy approaches currently in use for multiple-drug resistant Acinetobacter baumannii, including single phage therapy, phage cocktails, phage-antibiotic combination therapy, phage-derived enzymes active on Acinetobacter baumannii and some novel technologies based on phage interventions. Although phage therapy represents a potential treatment solution for multidrug-resistant Acinetobacter baumannii, further research is needed to unravel some unanswered questions, especially in regard to its in vivo applications, before possible routine clinical use.

A Simple Technique for Direct Immobilization of Target Enzymes from Cell Lysates Based on the SpyTag/SpyCatcher Spontaneous Reaction.

Many of the current methods for enzyme purification and immobilization suffer from several drawbacks, such as requiring tedious multistep procedures or long preparation, and being environmentally unfriendly, due to the chemicals and conditions involved. Thus, a simple technique for direct purification and immobilization of target enzymes from cell lysates was proposed. The elastin-like polypeptides (ELPs)-SpyCatcher chimera could mediate the formation of silica carriers within seconds and the target enzymes were then covalently immobilized on silica carriers via SpyCatcher/SpyTag spontaneous reaction. These tailor-made carriers were easily prepared, with precisely controlled morphology and size, as well as none-consuming surface modification needed, which could specifically immobilize the SpyTag-fused target enzymes from the cell lysate without pre-purification.

[Effect of weight growth velocity in the early stage after birth on neurodevelopment of preterm infants at the corrected age of 12 months].

OBJECTIVE: To study the effect of weight growth velocity in the early stage after birth on the neurodevelopment of preterm infants at the corrected age of 12 months. METHODS: Related data were collected from the preterm infants who were discharged from the Department of Neonatology, Third Affiliated Hospital of Guangzhou Medical University, from July 1, 2015 to December 31, 2019 and were followed up at the outpatient service of high-risk infants. According to the weight growth velocity from birth to the corrected gestational age of 40 weeks, the infants were divided into two groups: low velocity [< 10 g/(kg·d); n=21] and high velocity [≥10 g/(kg·d); n=87]. At the corrected ages of 3, 6, and 12 months, Gesell Developmental Schedules were used to evaluate and compare neurodevelopment between the two groups. RESULTS: At the corrected age of 12 months, the low velocity group had a significantly lower score of fine motor (P < 0.05) and a significantly higher abnormal rate of language ability score compared with high velocity (P < 0.05). For the preterm infants with a birth weight of < 1 500 g or ≥1 500 g, the low velocity group had a significantly lower score of fine motor than the high velocity group (P < 0.05); for the preterm infants with a birth weight of ≥1 500 g, the low velocity group had a significantly higher abnormal rate of language ability score than the high velocity group (P < 0.05). CONCLUSIONS: The weight growth velocity from birth to the corrected age of 40 weeks affects the development of fine motor and language in preterm infants at the corrected age of 12 months; however it needs to be further verified by large-sample studies.

Unique silica biomimetic mineralization of acidic elastin-like polypeptides without hydroxyl and charged residues.

Elastin-like polypeptides (ELPs), usually as a purification-tag, can be easily expressed and rapidly purified. We found ELPs[V9F-40], which did not contain hydroxyl or charged residues with the pI of 5.52, could biomimetically form silica when they were in ordered structure. The specific activity of ELPs[V9F-40] was 70.89 ± 9.53. Besides, the time needed for the completion of biomimetic silicification was about 138 s, which was only 1/3 of that for other reported peptides. The ELPs@silica is mainly spherical and the sizes of them were around 900 nm. However, currently presented mechanisms for peptide-triggered silica biomimetic mineralization could not explain such unique phenomenon. It would pave a new way for mining or designing peptides with such function, which provide a potential green method for the preparation of biomimetic silica particles. It would endow ELPs more functions and expand the application fields of ELPs such as the bioinspired synthesis of peptide biotemplated metal or nonmetal oxide nanoparticles.

Programmable stimuli-responsive polypeptides for biomimetic synthesis of silica nanocomposites and enzyme self-immobilization.

Bioinspired silicification is an attractive route for achieving unique silica nanocomposites. Herein, a novel, facile and inexpensive route for biosilica synthesis is developed using the stimuli-responsive elastin-like polypeptide (ELP). The ELP is precisely tailored to a silica-mineralizing peptide by programming it with lysine residues. The resulting cationic ELP[KV8F-40] is purified in ultrahigh yield using a chromatography-free ITC purification technique based on thermal-responsive property. Excitingly, the specific activity of ELP is 40-fold higher than that of silaffin. Besides, efficient and strong entrapment of ELP is achieved with over 98% of immobilization yield and less than 2% of leakage. These imply that cationic ELP may be used as a bifunctional tag (purification and immobilization) for fusion protein. An enzyme (xylanase) is therefore chosen to genetically fuse to ELP. The ELP-fused xylanase is purified by ELP with high purity (~98%) and enables the rapid (within minutes) self-immobilization. The immobilization yield was greater than 95%, and the immobilized xylanases hardly leaked from the silica matrix, demonstrating high efficiency of the self-immobilization process. The strategy developed here may provide a new opportunity for fabricating functional silica nanocomposites in a feasible and inexpensive pathway, which will have great potentials in the field of biotechnology.

Myricetin relieves LPS-induced mastitis by inhibiting inflammatory response and repairing the blood-milk barrier.

Mastitis, an inflammation of mammary gland, is a serious disease that affects the health of dairy cows around the world. Myricetin, a flavonoid from Bayberry, has been reported to suppress various inflammatory response. The aim of this study was to evaluate the effect of myricetin on lipopolysaccharide (LPS)-induced in vivo and in vitro mastitis model and clarify the underlying mechanism. In vivo experiments, myricetin attenuated the severity of inflammatory lesion and neutrophil infiltration. Moreover, myricetin pretreatment induced a significant decrease in the activity of myeloperoxidase (MPO) and the production of TNF-α, IL-6, and IL-1ß triggered by LPS. Myricetin pretreatment could also increase the integrity of the blood-milk barrier and upregulate the tight junction proteins in LPS-induced mice mastitis. In vitro, myricetin inhibited LPS-induced inflammatory response in mice mammary epithelial cells (mMECs). In the further mechanism studies, we found that the anti-inflammatory effect of myricetin was mediated by inhibiting LPS-induced phosphorylation of AKT, IKK-α, IκB-α, and P65 in vivo and in vitro. Collectively, these data suggested that myricetin effectively ameliorated the inflammatory response by inhibiting the AKT/IKK/NF-κB signaling pathway and repairing the integrity of blood-milk barrier in LPS-induced mice mastitis.

Molecular detection of Anaplasma infections in ixodid ticks from the Qinghai-Tibet Plateau.

Anaplasma species are tick-transmitted obligate intracellular bacteria that infect many wild and domestic animals and humans. The prevalence of Anaplasma spp. in ixodid ticks of Qinghai Province is poorly understood. In this study, a total of 1104 questing adult ticks were investigated for the infection of Anaplasma species. As a result, we demonstrated the total infection rates of 3.1, 11.1, 5.6, and 4.5% for A. phagocytophilum, A. bovis, A. ovis and A. capra, respectively. All of the tick samples were negative for A. marginale. The positive rates of A. phagocytophilum, A. ovis and A. capra in different tick species were significantly different. The positive rates of A. capra and A. bovis in the male ticks were significantly higher than that in the female ticks. Sequence analysis of A. ovis showed 99.5-100% identity to the previous reported isolates. The sequences of A. phagocytophilum had 100% identity to strains Ap-SHX21, JC3-3 and ZAM dog-181 from sheep, Mongolian gazelles, and dogs. Two genotypes of A. capra were found based on 16S rRNA, citrate synthase (gltA) gene and heat shock protein (groEL) gene analysis. In conclusion, A. bovis, A. ovis, A. phagocytophilum, and A. capra were present in the ticks in Qinghai Province. Anaplasma infection is associated with tick species, gender and distribution. These data will be helpful for understanding prevalence status of Anaplasma infections in ticks in Qinghai-Tibet Plateau.

Farrerol Ameliorates TNBS-Induced Colonic Inflammation by Inhibiting ERK1/2, JNK1/2, and NF-κB Signaling Pathway.

Farrerol, a type of 2, 3-dihydro-flavonoid, is obtained from Rhododendron. Previous studies have shown that Farrerol performs multiple biological activities, such as anti-inflammatory, antibacterial, and antioxidant activity. In this study, we aim to investigate the effect of Farrerol on colonic inflammation and explore its potential mechanisms. We found that the effect of Farrerol was evaluated via the 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis model in mice and found that Farrerol has a protective effect on TNBS-induced colitis. Farrerol administration significantly improved the weight change, clinical scores, colon length, and intestinal epithelium barrier damage and markedly decreased the inflammatory cytokines production in TNBS-induced mice. The protective effect of Farrerol was also observed in LPS-induced RAW264.7 cells. We found that Farrerol observably reduced the production of inflammatory mediators including IL-1ß, IL-6, TNF-α, COX-2, and iNOS in LPS-induced RAW264.7 cells via suppressing AKT, ERK1/2, JNK1/2, and NF-κB p65 phosphorylation. In conclusion, the study found that Farrerol has a beneficial effect on TNBS-induced colitis and might be a natural therapeutic agent for IBD treatment.

A novel method for simultaneous purification and immobilization of a xylanase-lichenase chimera via SpyTag/SpyCatcher spontaneous reaction.

We generated a bifunctional enzyme chimera containing the xylanase and lichenase coupled with SpyTag between them. Meanwhile, we generated another chimera containing SpyCatcher and elastin-like polypeptides (ELPs). As ELPs could bond to the xylanase-lichenase chimera through SpyTag/SpyCatcher spontaneous reaction in mild condition, which would lead to the formation of a 3-arm star multifunctional chimera. We purified the xylanase-lichenase by the non-chromatographic purification tag of ELPs. Interestingly, 57.5% of the xylanase and 47.2% of the lichenase in chimera self-assembled into insoluble active particles during the process of purification, which could serve as immobilized bifunctional enzymes. Notably, the immobilized chimera xylanase-lichenase showed a remarkable stability even after 10 reaction cycles, which retained around 56% (lichenase) and 44% (xylanase) of their initial activities, respectively. Moreover, the enhanced thermostability of the immobilized enzymes was also achieved. After incubating at 60 °C for 60 min, the residual activity of the immobilized lichenase was 35%, while the free one was only 24%. Unexpectedly, the free xylanase almost lost its activity when incubated at 55 °C for 60 min, whereas the immobilized xylanase retained 10% of its activity. However, the catalytic efficiency (kcat/Km) of the free xylanase was 1.7-fold higher than the immobilized one, while the free lichenase was 1.1-fold higher than the immobilized one. This is among the first known reports that two enzymes are purified and immobilized in one-step. This novel strategy is easy to scale up and may meet the demands of biofuel industry. It would have great potentials in other biotechnological fields, such as the multifunctional biomaterials systems.

Effect of parental physiological conditions and assisted reproductive technologies on the pregnancy and birth outcomes in infertile patients.

Assisted reproductive technologies (ART) are widely used to treat infertility. Emerging evidence suggested that ART was associated with perinatal or neonatal problems, however, little is known about the ART related risk factors. Here using 21136 ART cases, we determined the impacts of parental physiological conditions in the ART mediated pregnancy outcomes. In addition, we further evaluated the effects of three different ART methods (frozen-thawed embryo transfer [FET], in vitro fertilization [IVF] and intracytoplasmic sperm injection [ICSI]) in the pregnancy and birth outcomes in ART mediated pregnancy. Our data revealed that older parental age increases the risks of abortion, preterm birth and low body weight birth. Higher maternal BMI (Body mass index) level correlates with higher abortion rate. Moreover, pregnancy with multiple fetuses has severer adverse outcomes compared to singleton pregnancy. Among the three ART methods, ICSI is associated with lower ratios of ectopic pregnancy, abortion and deformity compared to FET and IVF. Our study revealed new clinical insights into the ART related risk factors and suggested that both the parental physiological conditions and ART methods should be evaluated to develop better ART mediated infertility treatments.

Scalable Feature Matching by Dual Cascaded Scalar Quantization for Image Retrieval.

In this paper, we investigate the problem of scalable visual feature matching in large-scale image search and propose a novel cascaded scalar quantization scheme in dual resolution. We formulate the visual feature matching as a range-based neighbor search problem and approach it by identifying hyper-cubes with a dual-resolution scalar quantization strategy. Specifically, for each dimension of the PCA-transformed feature, scalar quantization is performed at both coarse and fine resolutions. The scalar quantization results at the coarse resolution are cascaded over multiple dimensions to index an image database. The scalar quantization results over multiple dimensions at the fine resolution are concatenated into a binary super-vector and stored into the index list for efficient verification. The proposed cascaded scalar quantization (CSQ) method is free of the costly visual codebook training and thus is independent of any image descriptor training set. The index structure of the CSQ is flexible enough to accommodate new image features and scalable to index large-scale image database. We evaluate our approach on the public benchmark datasets for large-scale image retrieval. Experimental results demonstrate the competitive retrieval performance of the proposed method compared with several recent retrieval algorithms on feature quantization.

Semantic-Aware Co-Indexing for Image Retrieval.

In content-based image retrieval, inverted indexes allow fast access to database images and summarize all knowledge about the database. Indexing multiple clues of image contents allows retrieval algorithms search for relevant images from different perspectives, which is appealing to deliver satisfactory user experiences. However, when incorporating diverse image features during online retrieval, it is challenging to ensure retrieval efficiency and scalability. In this paper, for large-scale image retrieval, we propose a semantic-aware co-indexing algorithm to jointly embed two strong cues into the inverted indexes: 1) local invariant features that are robust to delineate low-level image contents, and 2) semantic attributes from large-scale object recognition that may reveal image semantic meanings. Specifically, for an initial set of inverted indexes of local features, we utilize semantic attributes to filter out isolated images and insert semantically similar images to this initial set. Encoding these two distinct and complementary cues together effectively enhances the discriminative capability of inverted indexes. Such co-indexing operations are totally off-line and introduce small computation overhead to online retrieval, because only local features but no semantic attributes are employed for the query. Hence, this co-indexing is different from existing image retrieval methods fusing multiple features or retrieval results. Extensive experiments and comparisons with recent retrieval methods manifest the competitive performance of our method.

Regionlets for Generic Object Detection.

Generic object detection is confronted by dealing with different degrees of variations, caused by viewpoints or deformations in distinct object classes, with tractable computations. This demands for descriptive and flexible object representations which can be efficiently evaluated in many locations. We propose to model an object class with a cascaded boosting classifier which integrates various types of features from competing local regions, each of which may consist of a group of subregions, named as regionlets. A regionlet is a base feature extraction region defined proportionally to a detection window at an arbitrary resolution (i.e., size and aspect ratio). These regionlets are organized in small groups with stable relative positions to be descriptive to delineate fine-grained spatial layouts inside objects. Their features are aggregated into a one-dimensional feature within one group so as to be flexible to tolerate deformations. The most discriminative regionlets for each object class are selected through a boosting learning procedure. Our regionlet approach achieves very competitive performance on popular multi-class detection benchmark datasets with a single method, without any context. It achieves a detection mean average precision of 41.7 percent on the PASCAL VOC 2007 dataset, and 39.7 percent on the VOC 2010 for 20 object categories. We further develop support pixel integral images to efficiently augment regionlet features with the responses learned by deep convolutional neural networks. Our regionlet based method won second place in the ImageNet Large Scale Visual Object Recognition Challenge (ILSVRC 2013).

Multiplicative updates for nonnegative quadratic programming.

Many problems in neural computation and statistical learning involve optimizations with nonnegativity constraints. In this article, we study convex problems in quadratic programming where the optimization is confined to an axis-aligned region in the nonnegative orthant. For these problems, we derive multiplicative updates that improve the value of the objective function at each iteration and converge monotonically to the global minimum. The updates have a simple closed form and do not involve any heuristics or free parameters that must be tuned to ensure convergence. Despite their simplicity, they differ strikingly in form from other multiplicative updates used in machine learning. We provide complete proofs of convergence for these updates and describe their application to problems in signal processing and pattern recognition.

Correlation of pneumonia score with electronic nose signature: A prospective study.

OBJECTIVES: Ventilator-associated pneumonia (VAP) is a frequent complication in patients in surgical intensive care units. Pneumonia scores, chest radiography, and bronchoscopy are all employed, but there is no gold standard test for the diagnosis of VAP. The electronic nose, a sensor of volatile molecules, is well suited to testing the breath of mechanically ventilated patients. Our objective was to determine the potential use of an electronic nose as a diagnostic adjunct in the detection of VAP. METHODS: We performed a prospective study of mechanically ventilated patients in a surgical intensive care unit. Clinical data, including temperature, white blood cell count, character and quantity of tracheal secretions, ratio of partial pressure of arterial oxygen to fraction of inspired oxygen, and chest radiographs, were collected, and a pneumonia score between 0 and 10 was calculated. Exhaled gas was sampled from the expiratory limb of the ventilator circuit. The gases were assayed with a commercially available electronic nose. Multidimensional data reduction analysis was used to analyze the results. RESULTS: Forty-four patients were studied. Fifteen patients had pneumonia scores of 7 or greater, and 29 patients had scores of 6 or less. With Fisher discriminant analysis and K-nearest neighbor analysis, the electronic nose was able to discriminate between the two groups. CONCLUSIONS: The electronic nose is a new technology that is inexpensive, noninvasive, and portable. We demonstrate its ability to predict pneumonia, based on a well-recognized scoring system. This technology promises to serve as a diagnostic adjunct in the management of VAP.

Reduced heterogeneity of muscle deoxygenation during heavy bicycle exercise.

PURPOSE: This study evaluated heterogeneity of muscle O2 dynamics in a single muscle during bicycle exercise using an eight-channel near-infrared continuous wave spectroscopy (NIRcws) mapping system. METHODS: Nine healthy subjects performed bicycle exercise at fixed workloads of 20, 40, 60, 80, and 100% maximal workload for 5 min at each level. Muscle oxygenation in the vastus lateralis (VL) during and after each exercise was monitored using the NIRcws mapping system. Pulmonary O2 uptake and heart rate were monitored continuously during the experiment. Blood samples were taken to measure blood lactate concentration at 30 s after each exercise stage. RESULTS: Half time reoxygenation, the time taken to reach a value of half-maximal recovery, was significantly delayed in distal sites compared with proximal sites of VL. Conversely, muscle deoxygenation for all measurement sites increased incrementally with higher exercise workloads, and no significant difference of deoxygenation level showed within each channel. However, relative dispersion of muscle deoxygenation during exercise significantly decreased when the workload increased. Moreover, relative dispersion of muscle deoxygenation between the subjects also decreased with an increase in the workload. CONCLUSION: Muscle deoxygenation in a single muscle was more heterogeneous at lower exercise workloads, and variations of the muscle deoxygenation heterogeneity between subjects were greater at lower exercise workloads.