Macromolecular Crowding Effect on Chitosan-Hyaluronic Acid Complexation and the Activity of Encapsulated Catalase.

The associative phase separation of charged biomacromolecules plays a key role in many biophysical events that take place in crowded intracellular environments. Such natural polyelectrolyte complexation and phase separation often occur at nonstoichiometric charge ratios with the incorporation of bioactive proteins, which is not studied as extensively as those complexations at stoichiometric ratios. In this work, we investigated how the addition of a crowding agent (polyethylene glycol, PEG) affected the complexation between chitosan (CS) and hyaluronic acid (HA), especially at nonstoichiometric ratios, and the encapsulation of enzyme (catalase, CAT) by the colloidal complexes. The crowded environment promoted colloidal phase separation at low charge ratios, forming complexes with increased colloidal and dissolution stability, which resulted in a smaller size and polydispersity (PDI). The binding isotherms revealed that the addition of PEG greatly enhanced the ion-pairing strength (with increased ion-pairing equilibrium constant Ka from 4.92 × 104 without PEG to 1.08 × 106 with 200 g/L PEG) and switched the coacervation from endothermic to exothermic, which explained the promoted complexation and phase separation. At the stoichiometric charge ratio, the enhanced CS-HA interaction in crowded media generated a more solid-like coacervate phase with a denser network, slower chain relaxation, and higher modulus. Moreover, both crowding and complex encapsulation enhanced the activity and catalytic efficiency of CAT, represented by a 2-fold increase in catalytic efficiency (Kcat/Km) under 100 g/L PEG crowding and CS-HA complex encapsulation. This is likely due to the lower polarity in the microenvironment surrounding the enzyme molecules. By a systematic investigation of both nonstoichiometric and stoichiometric charge ratios under macromolecular crowding, this work provided new insights into the complexation between natural polyelectrolytes in a scenario closer to an intracellular environment.

Antibacterial Activity and Multi-Targeted Mechanism of Action of Suberanilic Acid Isolated from Pestalotiopsis trachycarpicola DCL44: An Endophytic Fungi from Ageratina adenophora.

Methicillin-resistant Staphylococcus aureus (MRSA) is a highly threatening foodborne pathogen capable of causing severe organ and life-threatening diseases. Over the past years, various commercial antibiotics have been used to treat MRSA infections. However, these commercial antibiotics have not yielded efficient results and also cause other side effects; therefore, there is a need for the development of effective alternatives to replace these commercial antibiotics. Suberanilic acid, an amide alkaloid obtained from the endophytic fungus Pestalotiopsis trachycarpicola DCL44, has been identified as a significant antimicrobial agent. However, its antibiotic properties on multi-drug-resistant bacteria such as MRSA have not been fully explored. Therefore, to investigate the potential antimicrobial mechanism of suberanilic acid against MRSA, a quantitative proteomics approach using tandem mass tagging (TMT) was used. The results obtained in the study revealed that suberanilic acid targets multiple pathways in MRSA, including disruption of ribosome synthesis, inhibition of membrane translocation for nutrient uptake (ABC transporter system), and causing dysregulation of carbohydrate and amino acid energy metabolism. These results provide new insights into the mechanism of action of suberanilic acid against MRSA and offer technical support and a theoretical basis for the development of novel food antimicrobial agents derived from endophytic fungal origin.

Quantifying Turnover Dynamics of Selenoproteome by Isotopic Perturbation.

Selenium, as an essential trace element of life, is closely related to human health and is required to produce selenoproteins, a family of important functional proteins in many living organisms. All selenoproteins contain a special amino acid, selenocysteine, which often serves as their active-site residue, and the expression and activity of selenoproteins are fine-tuned. However, the turnover dynamics of selenoproteome has never been systematically investigated, especially in a site-specific manner for selenocysteines. In the current work, we developed a chemical proteomic strategy named "SElenoprotein Turnover Rate by Isotope Perturbation (SETRIP)" to quantitatively monitor the turnover dynamics of selenoproteins at the proteomic level. The kinetic rates and half-lives of nine selenoproteins were accurately measured by combining Na274SeO3 metabolic labeling with pulse-chase chemoproteomics. The half-lives of selenoproteins were measured to range from 6 to 32 h with the housekeeping selenoprotein glutathione peroxidases (GPX4) showing a faster turnover rate, implying that the hierarchy regulation also exists in the turnover of selenoproteins in addition to expression and activity. Our study generated a global portrait of dynamic changes in the selenoproteome and provided important clues to study the roles of selenium in biology.

The Critical Transition from Soluble Complexes to Colloidal Aggregates of Polyelectrolyte Complexes at Non-Stoichiometric Charge Ratios.

The transition from soluble to colloidal polyelectrolyte complex normally occurs at a critical non-stoichiometric charge ratio. Here, it is demonstrated that the conventional batch mixing produces heterogeneous binding and complexation, which can easily mask this soluble-colloidal complex transition (sol-col transition) even for weakly binding polyelectrolytes like polyacrylic acid (PAA) and poly(diallyldimethylammonium chloride) (PDADMAC). When mixed efficiently using multi-inlet vortex mixer (MIVM), the sol-col transition occurs beyond a critical charge ratio (n-/n+) and the large colloidal complexes are formed through the aggregation of small primary complexes (as revealed by atomic force microscopy). Moreover, the sol-col transition occurs at a constant charge ratio below the overlapping concentration (c*) of the long host polyelectrolyte, but at lower charge ratios above c* due to chain entanglement. When adding NaCl to the solution, the sol-col transition charge ratio first decreases, then remained stable for a period, and finally increased and vanished at high ionic strength. When replacing NaCl with chaotropic salts, the sol-col transition occurs at lower charge ratios, while kosmotropes has little impact. The solvent quality and polymer hydrophobicity effects are also discussed. With the assistance of rapid mixing, this study provides a more reliable way of studying the sol-col transition of polyelectrolyte complexes.

Extended aberration analysis in symmetry-free optical systems - part I: method of calculation.

The imaging performance evaluation of symmetry-free optical systems is of great importance during the correction process of optical design. However, due to the complexity and limitations of the available tools, the higher-order aberrations in the system cannot be well analyzed and are hard to control. In this paper, the theoretical background and the mathematical approach of a quantitative analysis method for surface-decomposed transverse aberration in the symmetry-free systems are introduced. With the mixed ray-tracing calculation in both real and paraxial cases, the implementations of full-order intrinsic/induced aberration, as well as the surface-additive Zernike coefficient fitting method are demonstrated. The applications of this method help assess the correction performance considering the relatively critical surfaces in an arbitrary off-axis system. The reliability and the accuracy of the method will be evaluated in part II with a test system. And as an illustration of the practical usage of the method for optical design, the corresponding applications on a group of lithographic systems will also be demonstrated.

Improved correction by freeform surfaces in prism spectrometer concepts.

The correction of spatial resolution and distortion in imaging spectrometer systems is of great importance due to their significant impact on efficiency and quality. In this study, we analyze the corrective power of freeforms added at different positions in various spectrometer systems for high-performance requirements. The results show that the combination of a freeform prism and a second freeform close to the image has the best correction of distortion while preserving spot size.

Differential Infrared Pyrometry for Determination of Microkelvin Temperature Variations.

Precise measurement of temperature is important in studies of chemical and biological systems as reaction kinetics are almost universally sensitive to temperature. However, the use of conventional temperature probes can introduce an exogenous temperature disturbance resulting in measurement artifacts. Infrared pyrometry is a noninvasive technique for temperature measurement, however, the challenge for current infrared pyrometry is low sensitivity to small temperature variations, which in many cases precludes determination of key diagnostic information. Here, we report a sensitive differential infrared pyrometer based on spatial modulation using a resonant oscillating mirror, which enables a sensitivity to temperature variations on the microkelvin scale. The instrument is employed to monitor minuscule heat evolution in an acid-base reaction and the decomposition of H2O2 by bovine liver catalase. The instrument holds great promise for monitoring the dynamics of heat evolution in a range of chemical and biological systems in a completely noninvasive manner.

Correction of 2D-telecentric scan systems with freeform surfaces.

For scanning systems the resolution, distortion as well as the telecentricity are important performance criteria. For two-dimensional scanning systems, scan mirrors deflecting in only one transverse direction are not allowing for telecentricity in x and y simultaneously in case of an axisymmetric system. It is possible to achieve two-dimensional telecentricity by splitting the pupils in x- and y-direction and shifting the principal planes in one dimension by changing the focal power using an anamorphic setup. However, for higher specifications concerning a large aperture and wide scanning angle, using cylindrical lenses are not enough to achieve a good system quality. It has been proved in many researches that freeform surfaces are effective to improve the resolution of systems without rotational symmetry. In this work, a systematic case study is presented to investigate the potential of freeform surfaces to improve the resolution, telecentricity, and distortion simultaneously. It is shown as a result that freeform surfaces offer large correction ability in all the three aspects concerning high specifications of 2D-telecentric anamorphic scan systems. This contribution provides the insight into the application of freeform surfaces in non-rotationally symmetric optical systems with refractive components.

Ant colony optimization in lens design.

As the most widely used optimization algorithm in optical design, the damped least square (DLS) method is advantageous for its fast convergence and deterministic optimization path. However, results are strongly dependent on the initial system and problematic when it is stuck in a local minimum in the searching space. To overcome these disadvantages, a biology intelligence-based algorithm, ant colony optimization (ACO) is implemented and tested for optical design tasks. Additionally, the ACO method has a better performance considering glass optimization. Two ACO versions, which are proved applicable, are introduced and their feasibility is assessed based on some case studies.

Ageratina adenophora causes intestinal integrity damage in goats via the activation of the MLCK/ROCK signaling pathway.

As a global toxin invasive species, the whole herb of Ageratina adenophora (A. adenophora) contains various sesquiterpenes, which can cause various degrees of toxic reactions characterized by inflammatory damage when ingested by animals. Current studies on the toxicity of A. adenophora have focused on parenchymatous organs such as the liver and spleen, but few studies have been conducted on the intestine as the organ that is first exposed to A. adenophora and digests and absorbs its toxic components. In this study, after feeding goats with 40 % A. adenophora herb powder for 90 d, we found that the intestinal structure of goats showed pathological changes characterized, and the damage to the small intestinal segments was more severe than that of the large intestine. The MLCK/ROCK signaling pathway was activated, the cytoskeleton underwent centripetal contraction, the composition of tight junctions between intestinal epithelial cells was altered table, Occludin, Claudin-1 and Zonula occluden (ZO-1) amount was decreased, and the intestinal mechanical barrier was disrupted. The intestinal damage markers diamine oxidase (DAO) and D-lactate (D-LA) levels were elevated. In addition, we also found that intestinal bacteria translocate and enter the portal vein to colonize the liver and mesenteric lymph nodes. The expression of intestinal pro-inflammatory factors and anti-inflammatory factors was changed, the intestinal immune function was disrupted. The present study is the first to analyze the mechanism of poisoning of A. adenophora from the intestinal tract in compound-gastric animals.

Theory of self-oscillation and mode locking in a longitudinal photoacoustic resonator.

The wave equation for pressure that governs generation of the photoacoustic effect possesses a forcing term proportional to the time derivative of the energy delivered to the gas per unit volume and time. A positive pressure fluctuation, with its accompanying density increase, thus increases the optical absorption and provides a positive feedback mechanism for sound generation. A theory for self-oscillation in a one-dimensional resonator is given. Expressions for the photoacoustic pressure are derived for the cases of highly and weakly absorbing gases that indicate mode-locked sound generation. Experiments with CO2 lasers are reported where evidence of the self-generation effect was sought.