Glucosamine induces cell death via proteasome inhibition in human ALVA41 prostate cancer cell

Glucosamine, a naturally occurring amino monosaccharide, has been reported to play a role in the regulation of apoptosis more than half century. However the effect of glucosamine on tumor cells and the involved molecular mechanisms have not been thoroughly investigated. Glucosamine enters the hexosamine biosynthetic pathway (HBP) downstream of the rate-limiting step catalyzed by the GFAT (glutamine:fluctose- 6-phosphate amidotransferase), providing UDPGlcNAc substrates for O-linked β-N-acetylglucosamine (O-GlcNAc) protein modification. Considering that O-GlcNAc modification of proteasome subunits inhibits its activity, we examined whether glucosamine induces growth inhibition via affecting proteasomal activity. In the present study, we found glucosamine inhibited proteasomal activity and the proliferation of ALVA41 prostate cancer cells. The inhibition of proteasomal activity results in the accumulation of ubiquitinated proteins, followed by induction of apoptosis. In addition, we demonstrated that glucosamine downregulated proteasome activator PA28γ and overexpression of PA28γ rescued the proteasomal activity and growth inhibition mediated by glucosamine. We further demonstrated that inhibition of O-GlcNAc abrogated PA28γ suppression induced by glucosamine. These findings suggest that glucosamine may inhibit growth of ALVA41 cancer cells through downregulation of PA28γ and inhibition of proteasomal activity via O-GlcNAc modification.     

Graphene Oxide-Based Stimuli-Responsive Platforms for Biomedical Applications

Graphene is a two-dimensional sp² hybridized carbon material that has attracted tremendous attention for its stimuli-responsive applications, owing to its high surface area and excellent electrical, optical, thermal, and mechanical properties. The physicochemical properties of graphene can be tuned by surface functionalization. The biomedical field pays special attention to stimuli-responsive materials due to their responsive abilities under different conditions. Stimuli-responsive materials exhibit great potential in changing their behavior upon exposure to external or internal factors, such as pH, light, electric field, magnetic field, and temperature. Graphene-based materials, particularly graphene oxide (GO), have been widely used in stimuli-responsive applications due to their superior biocompatibility compared to other forms of graphene. GO has been commonly utilized in tissue engineering, bioimaging, biosensing, cancer therapy, and drug delivery. GO-based stimuli-responsive platforms for wound healing applications have not yet been fully explored. This review describes the effects of different stimuli-responsive factors, such as pH, light, temperature, and magnetic and electric fields on GO-based materials and their applications. The wound healing applications of GO-based materials is extensively discussed with cancer therapy and drug delivery.     

Sensitive and rapid analytical method for the quantification of glucosamine in human plasma by ultra high performance liquid chromatography with tandem mass spectrometry

A highly sensitive and rapid ultra high performance liquid chromatography with tandem mass spectrometry method has been developed and validated for the determination of glucosamine in human plasma using miglitol as the internal standard. Special attention was paid to achieve the high throughput and sensitivity of the established method, and the absence of a matrix effect on the analytes. The sample preparation procedure involved a simple deproteinization step. The chromatographic separation was achieved on a Waters ACQUITY HSS Cyano column using a mixture of acetonitrile/2 mM ammonium acetate solution containing 0.03% formic acid (80:20, v/v) as the mobile phase with a very short run time of 1.5 min. This method was validated over the concentration range of 10–3000 ng/mL for glucosamine. The intra‐ and inter‐batch precision was <13.9% for the low, medium, and high quality control samples. The established method is highly sensitive with a lower limit of quantification of 10 ng/mL, low enough to determine the circadian rhythm on endogenous glucosamine level in human plasma, which has not been reported in detail until now. The method was successfully applied to characterize the pharmacokinetic profile of glucosamine in healthy volunteers following a single oral administration of 750 or 1500 mg glucosamine hydrochloride.     

激光光散射研究天花粉蛋白的聚集过程

运用激光光散射技术研究天花粉蛋白在水溶液及不同浓度KSCN水溶液中的聚集过程．KSCN的加入能提高天花粉在水溶液中的稳定性. KSCN浓度大于0．5mol•L－1时，天花粉溶液透明、稳定，溶液中天花粉以单个分子与聚集体两种形式存在．聚集体主要是由约120个天花粉分子组成，平均流体力学半径Rh值约为49nm，在溶液中排列疏松，类似θ溶剂中的无规线团。     

核酸适体生物传感器*

构建高速度、高特异性、高灵敏的蛋白质检测技术是目前蛋白质组学研究所面临的紧迫任务。传统蛋白质的检测主要利用抗体-抗原的特异相互作用。利用寡核苷酸间的严格的识别和亲和力而设计的人工合成寡核苷酸-适体（aptamer）的出现,使抗体抗原反应发生新的革命性变化。核酸适体对蛋白质的结合力和特异性可与抗原抗体间的作用力相媲美,且与抗体相比有许多优越性。因此利用核酸适体构建蛋白质的检测方法己引起许多科学工作者的关注。本文综述了核酸适体的发现(包括SELEX技术的原理),特点, 核酸适体生物传感器的原理、分类和应用,并对核酸适体生物传感器的发展进行了展望。     

Progress in Articular Cartilage Tissue Engineering: A Review on Therapeutic Cells and Macromolecular Scaffolds

Repair and regeneration of articular cartilage lesions have always been a major challenge in the medical field due to its peculiar structure (e.g., sparsely distributed chondrocytes, no blood supply, no nerves). Articular cartilage tissue engineering is considered as one promising strategy to achieve reconstruction of cartilage. With this perspective, the articular cartilage tissue engineering has been widely studied. Here, the recent progress of articular cartilage tissue engineering is reviewed. The ad hoc therapeutic cells and growth factors for cartilage regeneration are summarized and discussed. Various types of bio/macromolecular scaffolds together with their pros and cons are also reviewed and elaborated.     

低聚氨基葡萄糖的化学合成及修饰研究进展

低聚氨基葡萄糖是一种天然多糖,已在医药、农药等领域得到了应用。由于它具有良好的生物活性,因此,低聚氨基葡萄糖的化学合成和修饰成为该研究领域的重要方向之一。本文综述了近年来低聚氨基葡萄糖的化学合成和结构修饰方面的研究进展,着重介绍了化学修饰方法。     

The Application of Chitosan Nanostructures in Stomatology

Chitosan (CS) is a natural polymer with a positive charge, a deacetylated derivative of chitin. Chitosan nanostructures (nano-CS) have received increasing interest due to their potential applications and remarkable properties. They offer advantages in stomatology due to their excellent biocompatibility, their antibacterial properties, and their biodegradability. Nano-CSs can be applied as drug carriers for soft tissue diseases, bone tissue engineering and dental hard tissue remineralization; furthermore, they have been used in endodontics due to their antibacterial properties; and, finally, nano-CS can improve the adhesion and mechanical properties of dental-restorative materials due to their physical blend and chemical combinations. In this review, recent developments in the application of nano-CS for stomatology are summarized, with an emphasis on nano-CS’s performance characteristics in different application fields. Moreover, the challenges posed by and the future trends in its application are assessed.     

Aminoglycoside antibiotics may interfere with microbial amino sugar analysis

The amino sugars (e.g., glucosamine, galactosamine, mannosamine, muramic acid) in soils are frequently employed as biomarkers of microbial residues. The analysis of amino sugars in environmental matrices, however, is expected to be more complicated than their determination in isolated microbial cells. In this study, we employed a widely used protocol for amino sugar analysis, and found that some aminoglycoside antibiotics interfere with amino sugar quantification in vitro. The method converts the aminoglycosides to compounds that coelute with the aldononitrile acetate derivatives of the amino sugars. Specifically, streptomycin significantly interferes with muramic acid analysis, and kanamycin, tobramycin and amikacin hamper glucosamine measurement. Mass spectrometry confirmed that the interfering compounds from aminoglycosides are not actually genuine microbial amino sugar monomers (bacterial muramic acid or fungal glucosamine), and are most likely to be N-methyl glucosamine or 3-amino-3-deoxy-glucopyranose. In contrast to their effects on muramic acid and glucosamine analyses, aminoglycosides do not interfere with galactosamine and mannosamine quantification. The few data that exist on the environmental occurrence of aminoglycoside antibiotics suggest they occur at only trace levels. Our findings may have implications for the qualitative and quantitative validity of results from amino sugar assays in some context. Application of the aldononitrile acetate derivatization method to samples (especially in selective microbial cultures using aminoglycosides as inhibitors) requires that potential interference be evaluated.     

Therapeutic Potential of Dental Pulp Stem Cells According to Different Transplant Types

Stem cells are unspecialised cells capable of perpetual self-renewal, proliferation and differentiation into more specialised daughter cells. They are present in many tissues and organs, including the stomatognathic system. Recently, the great interest of scientists in obtaining stem cells from human teeth is due to their easy availability and a non-invasive procedure of collecting the material. Three key components are required for tissue regeneration: stem cells, appropriate scaffold material and growth factors. Depending on the source of the new tissue or organ, there are several types of transplants. In this review, the following division into four transplant types is applied due to genetic differences between the donor and the recipient: xenotransplantation, allotransplantation, autotransplantation and isotransplantation (however, due to the lack of research, type was not included). In vivo studies have shown that Dental Pulp Stem Cells (DPSCs)can form a dentin-pulp complex, nerves, adipose, bone, cartilage, skin, blood vessels and myocardium, which gives hope for their use in various biomedical areas, such as immunotherapy and regenerative therapy. This review presents the current in vivo research and advances to provide new biological insights and therapeutic possibilities of using DPSCs.     

Glycoprotein labeling using engineered variants of galactose oxidase obtained by directed evolution

A directed evolution approach has been used for the generation of variants of galactose oxidase (GOase) that can selectively oxidize glycans on glycoproteins. The aldehyde function introduced on the glycans D-mannose (Man) and D-N-acetyl glucosamine (GlcNAc) by the enzyme variants could then be used to label the glycoproteins and also whole cells that display mannosides on their surface.     

A Perylene diimide based fluorescent probe for caffeine in aqueous medium

Caffeine is a legal stimulant drug which has received considerable attention due to its widespread use as a beverage and in pharmaceutical formulations. However, reported chemosensors for caffeine are limited. In the present study use of a perylene diimide (PDI) derivative has been explored for the first time for detection and quantification of caffeine in an aqueous medium. Spectroscopic studies (UV-Vis, Fluorescence, FTIR and 1H-NMR) suggest that aspartic acid modified perylene diimide (PASP) may bind to caffeine through π-π interaction. This interaction results in immediate quenching of fluorescence and optical color change which can be perceived through naked eyes. This probe has been successfully used for bio-imaging of caffeine in living cells.     

Synthesis of conductive polymeric nanoparticles with hyaluronic acid based bioactive stabilizers for biomedical applications

In recent years, the use of organic materials to infer conductivity in biomedical devices has received increasing attention. Typical inorganic semiconductors and conductors are rigid and expensive, usually require multiple processing steps and are unsuitable for biomedical applications. Electrochemically or chemically doped conjugated polymers help to overcome these problems due to their stability, low cost, light weight and excellent electrical and optical properties. The conducting polymer poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) is the material of choice for biomedical applications as it is water soluble, however, there are growing concerns around its stabilizer, PSS, due to its release of acidic products upon degradation in-vivo. Here, we report the successful synthesis of PEDOT nanoparticles using hyaluronic acid (HA) as a stabilizer via an oxidative miniemulsion polymerisation technique. This improves the bioactivity and hydrophilicity of nanoparticles. The effect of varying amounts of HA and different molar ratios of EDOT:TOS has been studied and their role in the conductive and morphological properties of final nanoparticles has been fully elucidated. Furthermore, bioactivity and biocompatibility of the nanoparticles are demonstrated for customizable in vivo applications. Nanoparticles were found to have a conductivity up to 10 times greater than pristine PEDOT:PSS with increased addition of oxidant. The proposed easy-to-manufacture approach, along with the highlighted superior properties, expands the potential of conductive polymers in future customizable biological applications such as tissue scaffolds, nerve conduits and cardiac patches and represents a real breakthrough from the current state of the art.     

Photo-crosslinkable hydrogel and its biological applications

In the past few years,photo-crosslinkable hydrogels have drawn a great attention in tissue engineering applications due to their high biocompatibility and extracellular matrix(ECM)-like structure.They can be easily biofabricated through exposure of a photosensitive system composed of photo-crosslinkable hydrogels,photo-initiators and other compounds such as cells and therapeutic molecules,to ultraviolet or visible light.With the development of biofabrication methods,ma ny resea rchers studied the biological applications of photo-crosslinkable hydrogels in tissue engineering,such as vascular,wound dressing and bone engineering.This review highlights the biomaterials for photo-crosslinkable hydrogels,bio fabrication techniques and their biological applications in tissue engineering.Meanwhile,the challenges and prospects of photo-crosslinkable hydrogels are discussed as well.     

Utility of formaldehyde cross-linking and mass spectrometry in the study of protein-protein interactions

For decades, formaldehyde has been routinely used to cross-link proteins in cells, tissue, and in some instances, even entire organisms. Due to its small size, formaldehyde can readily permeate cell walls and membranes, resulting in efficient cross-linking, i.e. the formation of covalent bonds between proteins, DNA, and other reactive molecules. Indeed, formaldehyde cross-linking is an instrumental component of many mainstream analytical/cell biology techniques including chromatin immunoprecipitation (ChIP) of protein-DNA complexes found in nuclei; immunohistological analysis of protein expression and localization within cells, tissues, and organs; and mass spectrometry (MS)-compatible silver-staining methodologies used to visualize low abundance proteins in polyacrylamide gels. However, despite its exquisite suitability for use in the analysis of protein environments within cells, formaldehyde has yet to be commonly employed in the directed analysis of protein-protein interactions and cellular networks. The general purpose of this article is to discuss recent advancements in the use of formaldehyde cross-linking in combination with MS-based methodologies. Key advantages and limitations to the use of formaldehyde over other cross-linkers and technologies currently used to study protein-protein interactions are highlighted, and formaldehyde-based experimental approaches that are proving very promising in their ability to accurately and efficiently identify novel protein-protein and multiprotein interaction complexes are presented.     

后过渡金属催化烯烃可控/活性聚合的研究进展

烯烃活性聚合由于可以制备出预定分子量的窄分布聚合物,以及各种嵌段共聚物、末端功能化聚合物等而受到广泛关注.过渡金属催化的烯烃配位聚合反应活性高,催化剂性能可通过配体结构的修饰进行调节,聚合物微观结构易于调控,其活性聚合进一步拓展了对烯烃聚合物分子设计的手段,具有重要的意义.除了以钛、锆、钒等为金属中心的前过渡系催化剂之...     

Phosphopeptide enrichment with stable spatial coordination on a titanium dioxide coated glass slide

Recent advances in phosphoproteomics have established powerful tools to analyze phosphorylation events. However, their spatial localization is lost due to sample homogenization procedures prior to the analysis. Imaging mass spectrometry (IMS) has emerged as a method to visualize the spatial distribution of molecules in tissue samples, but its application is still limited to relatively abundant molecules. Due to low phosphorylation stoichiometry, direct detection and imaging of protein phosphorylation by MS has not been achieved yet. Therefore we have developed a novel phosphopeptide enrichment strategy as a potential tool for in situ affinity imaging MS (AIMS). A specific type of titanium dioxide (TiO₂)‐coated glass slides was designed and validated with casein tryptic digests for their ability to selectively retain phosphopeptides while maintaining their spatial coordination. Copyright © 2009 John Wiley & Sons, Ltd.     

Sugarcane proteomics: Establishment of a protein extraction method for 2‐DE in stalk tissues and initiation of sugarcane proteome reference map

Sugarcane is an important commercial crop cultivated for its stalks and sugar is a prized commodity essential in human nutrition. Proteomics of sugarcane is in its infancy, especially when dealing with the stalk tissues, where there is no study to date. A systematic proteome analysis of stalk tissue yet remains to be investigated in sugarcane, wherein the stalk tissue is well known for its rigidity, fibrous nature, and the presence of oxidative enzymes, phenolic compounds and extreme levels of carbohydrates, thus making the protein extraction complicated. Here, we evaluated five different protein extraction methods in sugarcane stalk tissues. These methods are as follows: direct extraction using lysis buffer (LB), TCA/acetone precipitation followed by solubilization in LB, LB containing thiourea (LBT), and LBT containing tris, and phenol extraction. Both quantitative and qualitative protein analyses were performed for each method. 2‐DE analysis of extracted total proteins revealed distinct differences in protein patterns among the methods, which might be due to their physicochemical limitations. Based on the 2‐D gel protein profiles, TCA/acetone precipitation‐LBT and phenol extraction methods showed good results. The phenol method showed a shift in pI values of proteins on 2‐D gel, which was mostly overcome by the use of 2‐D cleanup kit after protein extraction. Among all the methods tested, 2‐D cleanup‐phenol method was found to be the most suitable for producing high number of good‐quality spots and reproducibility. In total, 30 and 12 protein spots commonly present in LB, LBT and phenol methods, and LBT method were selected and subjected to eLD‐IT‐TOF‐MS/MS and nESI‐LC‐MS/MS analyses, respectively, and a reference map has been established for sugarcane stalk tissue proteome. A total of 36 nonredundant proteins were identified. This is a very first basic study on sugarcane stalk proteome analysis and will promote the unexplored areas of sugarcane proteome research.