Disruption and eradication of P. aeruginosa biofilms using nitric oxide-releasing chitosan oligosaccharides

Biofilm disruption and eradication were investigated as a function of nitric oxide- (NO) releasing chitosan oligosaccharide dose and the results compared with control (ie non-NO-releasing) chitosan oligosaccharides and tobramycin. Quantification of biofilm expansion/contraction and multiple-particle tracking microrheology were used to assess the structural integrity of the biofilm before and after antibacterial treatment. While tobramycin had no effect on the physical properties of the biofilm, NO-releasing chitosan oligosaccharides exhibited dose-dependent behavior with biofilm degradation. Control chitosan oligosaccharides increased biofilm elasticity, indicating that the scaffold may mitigate the biofilm disrupting power of nitric oxide somewhat. The results from this study indicate that nitric oxide-releasing chitosan oligosaccharides act as dual-action therapeutics capable of eradicating and physically disrupting P. aeruginosa biofilms.     

Rheological characterization of dilute acid pretreated softwood

Large-scale bioethanol production from lignocellulosic biomass will require high solids loading in the enzymatic hydrolysis step. However, slurries of pretreated lignocelluloses are complex fluids due to the fibrous nature, especially at high concentrations of water insoluble solids (WIS). A prerequisite for dealing with transport issues and for developing efficient full-scale processes is a fundamental understanding of the flow properties of pretreated lignocellulose. A comprehensive rheological characterization of dilute acid pretreated spruce has been carried out in this study, accounting for the effects of WIS concentration, particle size distribution (PSD), and the degree of enzymatic hydrolysis. The rheology of pretreated spruce slurries was found to be strongly dependent on the WIS concentration. The storage modulus (G'(LVR)) and yield stress showed typical power-law dependencies on volume fraction and WIS content. Milling of the pretreated material resulted in significantly higher yield stress and viscosity, likely due to narrower PSD, which suggests that the strength of the network of the coarsest fibers determines the rheology of these materials to a large extent. During enzymatic hydrolysis, yield stress and viscosity decreased dramatically, partly due to decreasing WIS content, but possibly also due to changes in fiber properties such as the chemical composition.     

Synthesis of Injectable Shear‐Thinning Biomaterials of Various Compositions of Gelatin and Synthetic Silicate Nanoplatelet

Injectable shear‐thinning biomaterials (iSTBs) have great potential for in situ tissue regeneration through minimally invasive therapeutics. Previously, an iSTB was developed by combining gelatin with synthetic silicate nanoplatelets (SNPs) for potential application to hemostasis and endovascular embolization. Hence, iSTBs are synthesized by varying compositions of gelatin and SNPs to navigate their material, mechanical, rheological, and bioactive properties. All compositions (each component percentage; 1.5–4.5%/total solid ranges; 3–9%) tested are injectable through both 5 Fr general catheter and 2.4 Fr microcatheter by manual pressure. In the results, an increase in gelatin contents causes decrease in swellability, increase in freeze‐dried hydrogel scaffold porosity, increase in degradability and injection force during iSTB fabrication. Meanwhile, the amount of SNPs in composite hydrogels is mainly required to decrease degradability and increase shear thinning properties of iSTB. Finally, in vitro and in vivo biocompatibility tests show that the 1.5–4.5% range gelatin–SNP iSTBs are not toxic to the cells and animals. All results demonstrate that the iSTB can be modulated with specific properties for unmet clinical needs. Understanding of mechanical and biological consequences of the changing gelatin–SNP ratios through this study will shed light on the biomedical applications of iSTB on specific diseases.     

Unusual penetration of phospholipid mono- and bilayers by Quillaja bark saponin biosurfactant

The interactions between a model phospholipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and a biosurfactant Quillaja Bark Saponin (QBS) obtained from the bark of Quillaja saponaria Molina were studied using simple models of biological membranes. QBS is known to interact strongly with the latter, exerting a number of haemolytic, cytotoxic and anti-microbial actions. The interaction of QBS dissolved in the subphase with DPPC monolayers and silicon-supported bilayers was studied above the cmc (10^− 3 M). Surface pressure relaxation and surface dilatational rheology combined with quartz crystal microbalance (QCM) and neutron reflectivity (NR) were employed for this purpose. The DPPC-penetrating abilities of QBS are compared with those of typical synthetic surfactants (SDS, CTAB and Triton X-100). We show that the penetration studies using high surface activity (bio)surfactants should be performed by a subphase exchange, not by spreading onto the surfactant solution. In contrast to the synthetic surfactants of similar surface activity, QBS does not collapse DPPC mono- and bilayers, but penetrates them, improving their surface dilatational elastic properties even in the highly compressed solid state. The dilatational viscoelasticity modulus increases from 204 mN/m for pure DPPC up to 310 mN/m for the QBS-penetrated layers, while it drops to near zero values in the case of the synthetic surfactants. The estimated maximum insertion pressure of QBS into DPPC monolayers exceeds the maximum surface pressure achievable in our setup, in agreement with the surface rheological response of the penetrated layers.     

Lipid-based capsaicin-loaded nano-colloidal biocompatible topical carriers with enhanced analgesic potential and decreased dermal irritation

Capsaicin (CP), a recent FDA-approved drug for the topical treatment of neuropathic pain, is associated with several side effects like irritation, burning sensation, and erythema, resulting in poor patient compliance. The present study is an attempt to study the effect of CP encasement in nano-lipoidal carriers (NLCs) on skin-transport characteristics, in vivo pharmacological performance, skin compliance, and stability of the finished product. The study also compares two methods of NLC preparation, namely microemulsification and rotary-evaporation for various attributes. The results demonstrated that microemulsion technique produced smaller nanoparticles vis-à-vis the rotary-evaporation method. Out of the various studied solid lipids, NLCs from stearic acid offered smallest size and the highest negative zeta potential. The NLC-gel offered higher skin permeation and skin retention of CP across LACA mice skin as compared with the conventional cream. The analgesic effect was observed to be enhanced substantially than that of the conventional cream when tested on a radiant mouse tail-flick model. The most alarming problems of skin-irritation and redness were successfully taken care by NLC-gel while the mice group receiving conventional cream showed marked changes in the skin histopathology. Besides the enhanced efficacy and decreased skin-irritation, the developed CP-NLCs also found to be stable and rheologically accepted formulation for the treatment of pain-associated disorders.     

Effect of carbon dioxide on the rheological behavior of submerged cultures of Chlorella minutissima in stirred tank reactors

The objective of this study was to quantify the effect of algal biomass concentration on the rheology of the algal culture broth. Batch cultivations of Chlorella minutissima were carried out with air and carbon dioxide in a stirred tank bioreactor with a working volume of 1.8 L. The apparent viscosity of the culture broth was significantly affected by the cell mass concentrations in the bioreactor. Culture broth containing 50 g/L cell mass from air fed was found to exhibit an apparent viscosity of 1.52 mPa.s. The apparent viscosity of the carbon‐dioxide‐fed cultivations was found to increase by 20% at a shear rate of 100 s^?1. The flow behavior of the system was adequately described by the Herschel–Bulkley model with a small yield stress.     

Effect of drying on the biological activities of a red microalgal polysaccharide

The red microalga Porphyridium sp. produces a polysaccharide exhibiting a variety of biological activities with potential for medical and cosmetic uses. For this reason, it is important that the drying process, which is the end point of production, should not destroy the natural characteristics of the material. The objective of this study was to evaluate the effect of drying at temperatures ranging from 40 to 140 degrees C on the bioactivities of the polysaccharide. Drying the polysaccharide at temperatures above 90 degrees C caused a significant decline in its biological activities (antiviral and anti-cell proliferation) and reduced elasticity, viscosity, and intrinsic viscosity relative to lyophilized polysaccharide and to the starting product. The relationship between molecular weight and intrinsic viscosity indicated that the polysaccharide takes a rigid coil conformation, which stiffens as a result of drying. FTIR analysis revealed that drying caused both significant conformational alterations in the polymer chains and changes in the interaction between the polysaccharide and the glycoprotein to which it is noncovalently associated. Differential scanning calorimetry analysis of the water adsorbed on the charged groups of the polysaccharide showed that drying at higher temperatures increased the bound water content due to dissociation of the polymer chains. Thus, it is recommended that the polysaccharide be dried in a two-step process in which free water is removed by convection and bound freezing water is removed by lyphophilization.     

Reducing noise in computed correlation functions using techniques from signal processing

Time correlation functions invariably suffer from random noise, especially at longer time intervals for which fewer data pairs are available. This noise is particularly of concern when calculating correlations that cannot be averaged over per-molecule contributions, such as stress in molecular simulations. In this work, a set of methods based in signal processing has been developed to reduce the inherent noise that is present in time- and frequency-domain representations of correlation functions. The stress time autocorrelation function, which leads to stress relaxation modulus and complex modulus, is used as an example. The difference between initial and final values of a time correlation function over a finite time domain is found to create so-called ‘leakage’ of noise from disallowed into harmonic frequencies during fast Fourier transformation. Decreasing this leakage effect through reflection to negative time and through applying a window function reduces noise levels significantly. Removing frequency components of insignificant magnitudes also provides significant noise reduction. Applying moving averages in the frequency and time domains also contributes to noise reduction. Specific results obtained by applying these methods to a model asphalt system enable more clear physical interpretations of the underlying relaxations after dramatic noise level reductions were attained.     

He-Ne激光结合丹参对类风湿性关节炎大鼠血液流变学指标的影响

目的:研究He-Ne激光结合丹参对类风湿性关节炎大鼠的治疗效果,以便为临床提供治疗风湿病的参考依据。方法:通过对健康大鼠注射鸡Ⅱ型胶原诱导后,成功建立了大鼠类风湿性关节炎的模型,随机分组后给予治疗,分析大鼠体重、血液流变学指标的变化。结果:1.与空白对照组相比,不同处理组大鼠类风湿关节炎体重增长幅度不同(P<0.05),其中模型组最小,丹参结合激光治疗组最高。2.与空白对照组相比,不同处理组的全血还原粘度低切、全血粘度(低、中、高切)、红细胞聚集指数均降低(P<0.05),其中模型组大鼠最高;而激光结合丹参治疗组最低。但全血还原粘度中、高切和红细胞压积没有统计学差异(P>0.05)。结论:丹参结合激光对Ⅱ型胶原诱导类风湿性关节炎大鼠体重、血液流变学指标均有一定程度的改善。     

蝮蛇抗栓酶对高粘血症患者血液流变与微循环影响的观察

静注蝮蛇抗栓酶并口服青龙胶囊治疗高粘血症１４０例患者。结果显示,蝮蛇抗栓酶能明显降低血液粘度,表现为全血粘度、血浆粘度、全血还原粘度及纤维蛋白原降低,同时降低甲襞微循环形态、流态及管周状态积分。探讨其改善血液粘度机制。