Paradox of complex diversity: Challenges in the diagnosis and management of bacterial keratitis

Bacterial keratitis continues to be one of the leading causes of corneal blindness in the developed as well as the developing world, despite swift progress since the dawn of the “anti-biotic era”. Although, we have expeditiously developed our understanding about the different causative organisms and associated pathology leading to keratitis, extensive gaps in knowledge continue to dampen the efforts required for early and accurate diagnosis, and management in these patients, resulting in poor clinical outcomes. The ability of the causative bacteria to subdue the therapeutic challenge stems from their large genome encoding complex regulatory networks, variety of unique virulence factors, and rapid secretion of tissue damaging proteases and toxins.In this review article, we provide an overview of the established diagnostic techniques and therapeutics for keratitis caused by various bacteria. We extensively report the recent in-roads through novel tools for accurately diagnosing mono- and poly-bacterial corneal infections. Furthermore, we outline the recent progress by our groups and others in understanding the sub-cellular genomic changes that lead to antibiotic resistance in these organisms. Finally, we discuss in detail, the novel therapies and drug delivery systems in development for the efficacious management of bacterial keratitis.     

丙烯酸酯共聚物涂膜中钛螯合物的交联作用

用红外光谱、紫外光谱、差示扫描量热等手段表征了掺杂体系内钛螯舍物(Ti-Ac)与丙烯酸酯共聚物的相互作用。测试了Ti-Ac用量对涂膜耐水性、耐热性及复溶性的影响。鲒果表明。当ωTi-Ac=0．015时涂膜的吸水率可下降到1％以下。且涂膜仍保持较好的复溶性(15s)。     

Effect of Alkyl Groups of Latent Cationic Catalysts on Cure and Dynamic Mechanical Behaviors of Epoxy Resins

Summary: The latent thermal cationic initiators, benzyl‐2,5‐dimethylpyrazinium hexafluoroantimonate (BDPH) and benzyl‐2‐ethylpyrazinium hexafluoroantimonate (BEPH), were synthesized to investigate the effect of substituted alkyl groups on cure and dynamic mechanical behaviors of difunctional epoxy system. The cure temperature and activation energy of the diglycidyl ether of bisphenol A (DGEBA)/BDPH were higher than those of the DGEBA/BEPH, resulting from the steric hindrance of the substituted groups. The cross‐linking density of the DGEBA/BDPH was higher than that of the DGEBA/BEPH, whereas the T_g's of both specimens are similar. This may be explained by the free volume and the intermolecular hydrogen bonding induced by the hydrogen of the substituted methyl groups. Consequently, the position and number of the substituted groups of the latent thermal initiator were very important in the control of the latent thermal and dynamic mechanical behaviors of the epoxy resin.

Dynamic DSC curves of DGEBA cured by each initiator.     

可生物降解的注射用药物传递系统研究进展

目的在大量文献的基础上对可注射的体内半固态药物传递系统进行综述 ,指出它们作为局部植入药物传递系统所存在的优、缺点及其前景。方法根据在体内获得固态化的机制不同 ,介绍形成这些系统的不同方法及类型。结果与结论这些系统主要是由可生物降解材料制成的 ,具有生物相容性好、应用方便、可局部给药、延缓药物释放等优点 ,促进了新型药物传递系统的发展     

Supramolecular Assembly‐Assisted Synthesis of Responsive Polymeric Materials with Controlled Chain Topologies

Tremendous developments, ranging from new synthetic strategies, properties, and novel functional applications, have emerged in the field of stimuli‐responsive polymeric materials. A variety of highly efficient chemical methodologies have been exploited to synthesize stimuli‐responsive polymers, aiming to control their molecular weight, polydispersity, chemical composition, monomer sequence, and chain topologies. Of particular interest is the emerging strategy of supramolecular assembly‐assisted polymer synthesis, which possesses combined advantages such as facile accessibility, design versatility, multifunctional integration, and promising functions. In this trend article, recent advances are elaborated concerning the fabrication of stimuli‐responsive functional polymers assisted by supramolecular self‐assembly. The fabrication of three main types of responsive polymers, namely, linear polymers, non‐linear shaped polymers, and crosslinked nanostructures, aided by templates of supramolecular assemblies will be discussed.

     

Glutaraldehyde in collagen gel formation

The effect of glutaraldehyde (GTA) on the course of collagen gel formation was studied by measuring the absorbance against time. It was found that the t_1/2 of fibril formation decreased with the addition of GTA and reached a minimum at a concentration of 6μl of GTA per g of collagen. For GTA concentrations, [GTA], above this value, t_1/2 increased again and fibril formation was inhibited at concentrations of about 50-60 μl of GTA per g of collagen. Thermal analysis showed that the denaturation temperature was the highest for the gels formed with [GTA] of 6 μl/g, the transition peak also being the sharpest. At this [GTA], the compressive rigidity of the gels was also the highest. For low [GTA], above and below the optimum value, the fibrils formed had the normal collagen periodicity when observed in the electron microscope. This study shows that collagen gels which find applications as biomaterials can be effectively crosslinked at the gelation stage itself by the addition of low concentrations of GTA.     

Bioinspired Photo‐Core‐Crosslinked and Noncovalently Connected Micelles From Functionalized Polystyrene and Poly(ethylene oxide) Homopolymers

In this paper, we report a simple and effective method for the preparation of stable core‐crosslinked micelles after the self‐assembly of thymine‐functionalized polystyrene (PVBT) and adenine‐terminated poly(ethylene oxide) (PEO‐A) homopolymers, and subsequent bioinspired photo‐crosslinking of the thymine units in PVBT. We obtained “graft‐like” copolymers from the interactions of PEO‐A with the PVBT chains through complementary multiple hydrogen bonding in a common solvent (dimethylformamide) after the addition of selective solvents (H₂O and MeCN for PVBT and PEO‐A, respectively). Stable micelles featuring PVBT as the core and PEO‐A as the shell were formed via selective solvent pairs; they were clearly visualized using transmission electronic microscopy and staining techniques. The shapes and sizes of the core/shell micelle structures did not change after exposure to UV light, revealing the enhanced dimensional stability of these photo‐core‐crosslinked micelles.     

Advanced Functional Polymers for Increasing the Stability of Organic Photovoltaics

The development of new advanced polymers for improving the stability of OPV is reviewed. Two main degradation pathways for the OPV active layer are identified: photochemically initiated reactions primarily starting in the side chains and morphological changes that degrade the important nanostructure. Chemical units can be introduced that impart an increased stability. Similarly, the morphological degradation of the optimal nanostructure can be reduced. Active polymers and blends with acceptor material are used to create nanoparticle links with controlled size. Most of these advanced polymers and processing methods have only been utilized in small‐scale devices prepared by standard techniques such as spin coating, but a few cases of roll‐to‐roll processed solar cells with heat‐cleaved side chains are discussed.