Amorphous solid dispersion (ASD) can accelerate a project by improving dissolution rate and solubility, offering dose escalation flexibility and excipient acceptance for toxicology studies, as well ...as providing adequate preclinical and clinical exposure. The prerequisite physicochemical properties for a compound to form a stable ASD are glass-forming ability and low-crystallization tendency, which can be assessed using computational tools and experimental methods. Polymer excipient screening by in silico miscibility prediction and experimental screening techniques is discussed. Improved technologies for polymer screening with minimal quantity of drug substance, and the scalability of ASD from bench to commercial are reviewed. Considerations of in vitro evaluations, preclinical animal selection, and the translation of the preclinical results to clinical studies are also discussed. Better understanding of how polymers improve the stability of the amorphous phase in the solid state and how ASD improves bioavailability have facilitated the applications of ASD ranging from discovery research to preclinical development and further to commercialization. With the understanding of how ASDs are currently used in the pharmaceutical industry and what challenges remain to be solved, ASD can be applied to solve drug formulation problems at given research and development stages.
Relative to the apolipoprotein E (apoE) E3 allele of the APOE gene, apoE4 strongly increases the risk for the development of late-onset Alzheimer’s disease. However, apoE4 differs from apoE3 by only ...a single amino acid at position 112, which is arginine in apoE4 and cysteine in apoE3. It remains unclear why apoE3 and apoE4 are functionally different. Described here is a proposal for understanding the functional differences between these two isoforms with respect to lipid binding. A mechanism is proposed that is based on the full-length monomeric structure of the protein, on hydrogen–deuterium exchange mass spectrometry data, and on the role of intrinsically disordered regions to control protein motions. It is proposed that lipid binds between the N-terminal and C-terminal domains and that separation of the two domains, along with the presence of intrinsically disordered regions, controls this process. The mechanism explains why apoE3 differs from apoE4 with respect to different lipid-binding specificities, why lipid increases the binding of apoE to its receptor, and why specific residues are conserved.
Allosteric drugs, which bind to proteins in regions other than their main ligand-binding or active sites, make it possible to target proteins considered "undruggable" and to develop new therapies ...that circumvent existing resistance. Despite growing interest in allosteric drug discovery, rational design is limited by a lack of sufficient structural information about alternative binding sites in proteins. Previously, we used Markov State Models (MSMs) to identify such "cryptic pockets," and here we describe a method for identifying compounds that bind in these cryptic pockets and modulate enzyme activity. Experimental tests validate our approach by revealing both an inhibitor and two activators of TEM β-lactamase (TEM). To identify hits, a library of compounds is first virtually screened against either the crystal structure of a known cryptic pocket or an ensemble of structures containing the same cryptic pocket that is extracted from an MSM. Hit compounds are then screened experimentally and characterized kinetically in individual assays. We identify three hits, one inhibitor and two activators, demonstrating that screening for binding to allosteric sites can result in both positive and negative modulation. The hit compounds have modest effects on TEM activity, but all have higher affinities than previously identified inhibitors, which bind the same cryptic pocket but were found, by chance, via a computational screen targeting the active site. Site-directed mutagenesis of key contact residues predicted by the docking models is used to confirm that the compounds bind in the cryptic pocket as intended. Because hit compounds are identified from docking against both the crystal structure and structures from the MSM, this platform should prove suitable for many proteins, particularly targets whose crystal structures lack obvious druggable pockets, and for identifying both inhibitory and activating small-molecule modulators.
The use of cell cycle inhibitors has necessitated a better understanding of the cell cycle in tumor biology to optimize the therapeutic approach. Cell cycle aberrations are common in cancers, and it ...is increasingly acknowledged that these aberrations exert oncogenic effects beyond the cell cycle. Multiple facets such as cancer metabolism, immunity and metastasis are also affected, all of which are beyond the effect of cell proliferation alone. This review comprehensively summarized the important recent findings and advances in these interrelated processes. In cancer metabolism, cell cycle regulators can modulate various pathways in aerobic glycolysis, glucose uptake and gluconeogenesis, mainly through transcriptional regulation and kinase activities. Amino acid metabolism is also regulated through cell cycle progression. On cancer metastasis, metabolic plasticity, immune evasion, tumor microenvironment adaptation and metastatic site colonization are intricately related to the cell cycle, with distinct regulatory mechanisms at each step of invasion and dissemination. Throughout the synthesis of current understanding, knowledge gaps and limitations in the literature are also highlighted, as are new therapeutic approaches such as combinational therapy and challenges in tackling emerging targeted therapy resistance. A greater understanding of how the cell cycle modulates diverse aspects of cancer biology can hopefully shed light on identifying new molecular targets by harnessing the vast potential of the cell cycle.
TEM β-lactamase confers bacteria with resistance to many antibiotics and rapidly evolves activity against new drugs. However, functional changes are not easily explained by differences in crystal ...structures. We employ Markov state models to identify hidden conformations and explore their role in determining TEM's specificity. We integrate these models with existing drug-design tools to create a new technique, called Boltzmann docking, which better predicts TEM specificity by accounting for conformational heterogeneity. Using our MSMs, we identify hidden states whose populations correlate with activity against cefotaxime. To experimentally detect our predicted hidden states, we use rapid mass spectrometric footprinting and confirm our models' prediction that increased cefotaxime activity correlates with reduced Ω-loop flexibility. Finally, we design novel variants to stabilize the hidden cefotaximase states, and find their populations predict activity against cefotaxime in vitro and in vivo. Therefore, we expect this framework to have numerous applications in drug and protein design.
The shape of a neuron changes dramatically during development. New work reports a novel septin cytoskeleton network that is important in establishing proper neuronal morphology.
The shape of a neuron ...changes dramatically during development. New work reports a novel septin cytoskeleton network that is important in establishing proper neuronal morphology.
Reversible post-translational modification by poly(ADP-ribose) (PAR) regulates chromatin structure, DNA repair and cell fate in response to genotoxic stress. PAR glycohydrolase (PARG) removes PAR ...chains from poly ADP-ribosylated proteins to restore protein function and release oligo(ADP-ribose) chains to signal damage. Here we report crystal structures of mammalian PARG and its complex with a substrate mimic that reveal an open substrate-binding site and a unique 'tyrosine clasp' enabling endoglycosidic cleavage of branched PAR chains.
The purpose of this study was to determine whether thoracic endovascular aortic repair reduces death and morbidity compared with open surgical repair for descending thoracic aortic disease.
A ...comprehensive search was undertaken among the 4 major databases (PubMed, Embase, Scopus, and Ovid) to identify all randomized and nonrandomized controlled trials comparing open versus endovascular repair in thoracic aortic aneurysm. Databases where evaluated and assessed to July 2017. Odds ratios, weighted mean differences, or standardized mean differences and their 95% confidence intervals were analyzed.
A total of 14,580 patients were analyzed in total of 13 articles, which were included in the synthesis of the meta-analysis. A total of 10,672 patients had open repair, and 3,908 patients had endovascular repair. Patients undergoing open repair were younger (mean of 65.1 years vs. 70.0 years, P = 0.0009), and there was higher elective rate in open repair patient (83.4% vs. 81%, P = 0.36). Duration of intensive care and total hospital stay was much shorter in endovascular patients (4.5 vs. 8.5 days, P = 0.002 and 5.7 vs. 9.5 days, P = 0.0004). Postoperative stroke was similar in both groups (P = 0.58); however, higher rate of paraplegia noted in open repair group (P = 0.007). The rate of renal failure (P = 0.01) and cardiac complications (P < 0.0001) was higher in the open repair group. The rate of vascular complications was much higher in the endovascular group of patients (5.29% vs. 1.17%, P = 0.002). Operative mortality was higher in endovascular procedures (4.4% vs. 3.2%, P = 0.005); however, 1- and 5-year mortality showed no statistical difference between the endovascular and open repair groups (22.19%, vs. 24.04%, P = 0.59, and 44.26% vs. 37.37%, P = 0.49).
The present meta-analysis shows that endovascular repair of thoracic aortic aneurysm gives better perioperative outcomes during inhospital stay although the 1- and 5-year mortality remains the same in both groups; but the long-term outcome is yet to be established. A long-term data and studies are required to give a better understanding of comparing these 2 techniques beyond 5 years of follow-up.
As display technology advances in color gamut, the potential of experiencing higher degree of observer metamerism is more likely with narrow bandwidth stimuli display devices. In previous studies, it ...is confirmed that observer metamerism was introduced in soft proofing with monitor and color grading with projector scenarios, and also led to serious implications. Hence, it is desired to investigate whether laser‐based projection system would introduce observer metamerism compared to halogen‐based projection system. In this study, a two‐part experiment was designed and conducted. Experiment 1 was based on color patches and experiment 2 was based on test images. Intra‐observer and inter‐observer variability were calculated and analyzed. Both experiments had illustrated observer metamerism was introduced in laser‐based projection system. Comparison to CIE Standard Observers was also conducted for each experiment, and the results had suggested that the CIE Standard Observers were not suitable for laser‐based projection system. A new observer category was required at least for the group of observers participating the experiments. A quick method to transform the content from the CIE 1964 Standard Observer for color patches or the CIE 1931 Standard Observer for images has been established in experiment 1, and this quick method could help to facilitate the growth of personalized color management system.
The aim of this study is to solve a problem of denoising and artifact removal from in vivo multispectral photoacoustic imaging when the level of noise is not known a priori. The study analyzes Wiener ...filtering in Fourier domain when a family of anisotropic shape filters is considered. The unknown noise and signal power spectral densities are estimated using spectral information of images and the autoregressive of the power 1 ( AR(1)) model. Edge preservation is achieved by detecting image edges in the original and the denoised image and superimposing a weighted contribution of the two edge images to the resulting denoised image. The method is tested on multispectral photoacoustic images from simulations, a tissue-mimicking phantom, as well as in vivo imaging of the mouse, with its performance compared against that of the standard Wiener filtering in Fourier domain. The results reveal better denoising and fine details preservation capabilities of the proposed method when compared to that of the standard Wiener filtering in Fourier domain, suggesting that this could be a useful denoising technique for other multispectral photoacoustic studies.
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