Direct peptide bioconjugation/PEGylation at tyrosine with linear and branched polymeric diazonium salts

Direct polymer conjugation at peptide tyrosine residues is described. In this study Tyr residues of both leucine enkephalin and salmon calcitonin (sCT) were targeted using appropriate diazonium salt-terminated linear monomethoxy poly(ethylene glycol)s (mPEGs) and poly(mPEG) methacrylate prepared by atom transfer radical polymerization. Judicious choice of the reaction conditions-pH, stoichiometry, and chemical structure of diazonium salt-led to a high degree of site-specificity in the conjugation reaction, even in the presence of competitive peptide amino acid targets such as histidine, lysines, and N-terminal amine. In vitro studies showed that conjugation of mPEG 2000 to sCT did not affect the peptide's ability to increase intracellular cAMP induced in T47D human breast cancer cells bearing sCT receptors. Preliminary in vivo investigation showed preserved ability to reduce [Ca 2+] plasma levels by mPEG 2000-sCT conjugate in rat animal models. © 2012 American Chemical Society

Restoration of rat colonic epithelium after in situ intestinal instillation of the absorption promoter, sodium caprate

Sodium caprate (C10) is an oral absorption promoter that is currently in clinical trials as a component of solid dosage forms for poorly permeable small molecules and peptides. Clinical data with zoledronic acid tablets suggest that significant delivery along with acceptable safety can be achieved from a once-a-week dosing regime. C10 has surfactant-like properties at the high doses used in vivo and therefore we examined its effects on rat intestinal epithelium following intestinal instillation. Results: Addition of 100 mM concentrations of C10 with the paracellular flux marker, fluorescein isothiocyanate-dextran 4 kDa, permitted a bioavailability of 33% to be achieved. When C10 was added 10, 30 and 60 min in advance of fluorescein isothiocyanate-dextran 4 kDa, enhancement still occurred, but was progressively reduced. Histology revealed that the permeability increase was likely related in part to superficial epithelial damage caused in the first few minutes of exposure, which was rapidly repaired within 30–60 min. Conclusions: Design of optimized dosage forms containing C10 should co-release the payload and promoter close to the epithelium in high concentrations. While C10 induces some epithelial damage, its remarkable capacity for epithelial repair may render this effect insignificant in vivo.Science Foundation Irelan

Epithelial Tight Junctional Changes in Colorectal Cancer Tissues

Colorectal cancer (CRC) is one of the most common cancers in the western world. Early screening and detection could be highly preventative and therefore reduce mortality. Tight junctions (TJ) are well known for their function in controlling paracellular traffic of ions and molecules. It has become increasingly evident that TJs play a crucial role in maintaining cell-cell integrity, and the loss of cell junctional sealing could involve itself in the processes of carcinoma and cancer metastasis. If correlations between altered TJ proteins and CRC presence or invasiveness could be established, they may serve as important markers and guidelines for prophylactic and prognostic purposes, along with other screening methods. This review will present recent data from clinical and animal studies showing how altered TJ protein expression is a feature of certain CRCs. The up-regulation of claudin-1 in many CRCs is especially noteworthy. The focus of this article is simply on the association – however imperfect – between CRC and the major TJ transmembrane barrier proteins, namely claudins and occludin. Any causal relationship between TJ protein change and neoplasia remains conclusively unproven at present

Optimization of Miller Cycle, EGR, and VNT on Performance and NOx Emission of a Diesel Engine for Range Extender at High Altitude

Due to the increasing sales of extended-range hybrid vehicles and the increasingly stringent emission regulations for light vehicles in China, the performance and emission of diesel engines for range extenders in the plateau region have attracted increasing attention. In order to obtain the superior performance of diesel engines for range extenders operating at high altitudes, a multi-objective optimization of the optimal economic operating point of the diesel engine was performed at an altitude of 1960 m. A diesel engine system model with MC-EGR-VNT (MEV) technology was developed using GT-Power based on the data of the engine bench to analyze the effects of the Miller cycle (MC), exhaust gas recirculation (EGR), and variable nozzle turbine (VNT) technologies on the power, economy, and emission performance of high-speed diesel engines. The response surface method (RSM) design was carried out with the Miller cycle rate (MCR), EGR value opening, VNT nozzle opening as variable factors and torque, brake-specific fuel consumption (BFSC), nitrogen oxide (NOx) emission as optimization objectives based on Box Behnken Design (BBD). The optimization results showed that the torque and BFSC remained almost constant, and NOx emission decreased by 59.5% compared with the original machine. The proposed multi-objective optimization method could make the diesel engine with a MEV system achieve a good comprehensive performance

Spatial and Temporal Patterns of Carbon and Water Use Efficiency on the Loess Plateau and Their Influencing Factors

Quantitative assessment of the dynamics of carbon and water use efficiency on the Loess Plateau in the context of complex climate change and its driving mechanisms is important for the improvement of the regional ecological environment and the enhancement of ecological service functions. In order to assess the impact of climate change and human activities on the carbon and water use efficiency of the Loess Plateau, this study investigates the spatial and temporal rates of change in CUE, WUE, and meteorological factors at the image metric scale using one-dimensional linear fit regression, investigates the spatial correlation between CUE and meteorological factors using partial correlation analysis, and quantifies the relative contributions of human activities to CUE and WUE using residual analysis. The following are the study’s conclusions: (1) The CUE and WUE of the Loess Plateau decreased geographically from 2000 to 2020, and both the CUE and WUE of the Loess Plateau exhibited a non-significant declining trend (p > 0.05), with the CUE falling at a rate of 0.001/10a (a: year) and the WUE decreasing at a rate of 0.047/10a (a: year). (2) From 2000 to 2020, the mean values of the CUE and WUE of the Loess Plateau were 0.60 and 1.75, respectively, with a clear spatial difference. (3) CUE was favorably linked with precipitation in 56.51% of the Loess Plateau, dispersed throughout the south-central portion of the Loess Plateau and Inner Mongolia, whereas the biased association with temperature was not statistically significant and often negative. (4) An examination of residuals revealed that human activities affected the trend of CUE and WUE to some degree. Only the WUE residuals of evergreen broadleaf forests exhibited a strong upward trend that was considerably influenced by people. In conclusion, this study used remote sensing image data and meteorological data to systematically analyze the spatial and temporal dynamic patterns of carbon use efficiency and water use efficiency on the Loess Plateau over the past 21 years, as well as the characteristics of their responses to climate change and human activities, thereby providing theoretical guidance for the study of carbon and water cycles in terrestrial ecosystems on the Loess Plateau

Advances in PEGylation of important biotech molecules : delivery aspects

Background: Although various injected peptide and protein therapeutics have been developed successfully over the past 25 years, several pharmacokinetic and immunological challenges are still encountered that can limit the efficacy of both novel and established biotech molecules. Objective and method: PEGylation is a popular technique to address such properties. PEGylated drugs exhibit prolonged half-life, higher stability, water solubility, lower immunogenicity and antigenicity, as well as potential for specific cell targeting. Although PEGylated drug conjugates have been on the market for many years, the technology has steadily developed in respect of site-specific chemistry, chain length, molecular weights and purity of conjugate. These developments have occurred in parallel to improvements in physicochemical methods of characterization. Conclusion: This review will discuss recent achievements in PEGylation processes with an emphasis on novel PEG-drugs constructs, the unrealized potential of PEGylation for non-injected routes of delivery, and also on PEGylated versions of polymeric nanoparticles, including dendrimers and liposomes

Short-Term Trajectory Prediction Based on Hyperparametric Optimisation and a Dual Attention Mechanism

Highly accurate trajectory prediction models can achieve route optimisation and save airspace resources, which is a crucial technology and research focus for the new generation of intelligent air traffic control. Aiming at the problems of inadequate extraction of trajectory features and difficulty in overcoming the short-term memory of time series in existing trajectory prediction, a trajectory prediction model based on a convolutional neural network-bidirectional long short-term memory (CNN-BiLSTM) network combined with dual attention and genetic algorithm (GA) optimisation is proposed. First, to autonomously mine the data association between input features and trajectory features as well as highlight the influence of important features, an attention mechanism was added to a conventional CNN architecture to develop a feature attention module. An attention mechanism was introduced at the output of the BiLSTM network to form a temporal attention module to enhance the influence of important historical information, and GA was used to optimise the hyperparameters of the model to achieve the best performance. Finally, a multifaceted comparison with other typical time-series prediction models based on real flight data verifies that the prediction model based on hyperparameter optimisation and a dual attention mechanism has significant advantages in terms of prediction accuracy and applicability

Methods for the Discovery and Identification of Small Molecules Targeting Oxidative Stress-Related Protein–Protein Interactions: An Update

The oxidative stress response pathway is one of the hotspots of current pharmaceutical research. Many proteins involved in these pathways work through protein–protein interactions (PPIs). Hence, targeting PPI to develop drugs for an oxidative stress response is a promising strategy. In recent years, small molecules targeting protein–protein interactions (PPIs), which provide efficient methods for drug discovery, are being investigated by an increasing number of studies. However, unlike the enzyme–ligand binding mode, PPIs usually exhibit large and dynamic binding interfaces, which raise additional challenges for the discovery and optimization of small molecules and for the biochemical techniques used to screen compounds and study structure–activity relationships (SARs). Currently, multiple types of PPIs have been clustered into different classes, which make it difficult to design stationary methods for small molecules. Deficient experimental methods are plaguing medicinal chemists and are becoming a major challenge in the discovery of PPI inhibitors. In this review, we present current methods that are specifically used in the discovery and identification of small molecules that target oxidative stress-related PPIs, including proximity-based, affinity-based, competition-based, structure-guided, and function-based methods. Our aim is to introduce feasible methods and their characteristics that are implemented in the discovery of small molecules for different types of PPIs. For each of these methods, we highlight successful examples of PPI inhibitors associated with oxidative stress to illustrate the strategies and provide insights for further design