Cryo-EM Structure of a Novel Calicivirus, Tulane Virus.

Tulane virus (TV) is a newly isolated cultivatable calicivirus that infects juvenile rhesus macaques. Here we report a 6.3 Å resolution cryo-electron microscopy structure of the TV virion. The TV virion is about 400 Å in diameter and consists of a T = 3 icosahedral protein capsid enclosing the RNA genome. 180 copies of the major capsid protein VP1 (~57 KDa) are organized into two types of dimers A/B and C/C and form a thin, smooth shell studded with 90 dimeric protrusions. The overall capsid organization and the capsid protein fold of TV closely resemble that of other caliciviruses, especially of human Norwalk virus, the prototype human norovirus. These close structural similarities support TV as an attractive surrogate for the non-cultivatable human noroviruses. The most distinctive feature of TV is that its C/C dimers are in a highly flexible conformation with significantly reduced interactions between the shell (S) domain and the protruding (P) domain of VP1. A comparative structural analysis indicated that the P domains of TV C/C dimers were much more flexible than those of other caliciviruses. These observations, combined with previous studies on other caliciviruses, led us to hypothesize that the enhanced flexibility of C/C dimer P domains are likely required for efficient calicivirus-host cell interactions and the consequent uncoating and genome release. Residues in the S-P1 hinge between the S and P domain may play a critical role in the flexibility of P domains of C/C dimers

Circumventing antimicrobial-resistance and preventing its development in novel, bacterial infection-control strategies

INTRODUCTION: Development of new antimicrobials with ever 'better' bacterial killing has long been considered the appropriate response to the growing threat of antimicrobial-resistant infections. However, the time-period between the introduction of a new antibiotic and the appearance of resistance amongst bacterial pathogens is getting shorter and shorter. This suggests that alternative pathways than making ever 'better' antimicrobials should be taken. AREAS COVERED: This review aims to answer the questions (1) whether we have means to circumvent existing antibiotic-resistance mechanisms, (2) whether we can revert existing antibiotic-resistance, (3) how we can prevent the development of antimicrobial-resistance against novel infection-control strategies, including nano-antimicrobials. EXPERT OPINION: Relying on relieving antibiotic-pressure and natural outcompeting of antimicrobial-resistant bacteria seems an uncertain way out of the antibiotic-crisis facing us. Novel, non-antibiotic, nanotechnology-based infection control-strategies are promising. At the same time, rapid development of new resistance mechanisms once novel strategies is taken into global clinical use, may not be ruled out and must be closely monitored. This suggests focusing research and development on designing suitable combinations of existing antibiotics with new nano-antimicrobials in a way that induction of new antimicrobial-resistance mechanisms is avoided. The latter suggestion, however, requires a change of focus in research and development

PAMAM dendrimers with dual-conjugated vancomycin and Ag-nanoparticles do not induce bacterial resistance and kill vancomycin-resistant Staphylococci

The effective life-time of new antimicrobials until the appearance of the first resistant strains is steadily decreasing, which discourages incentives for commercialization required for clinical translation and application. Therefore, development of new antimicrobials should not only focus on better and better killing of antimicrobial-resistant strains, but as a paradigm shift on developing antimicrobials that prevent induction of resistance. Heterofunctionalized, poly-(amido-amine) (PAMAM) dendrimers with amide-conjugated vancomycin (Van) and incorporated Ag nanoparticles (AgNP) showed a 6-7 log reduction in colony-forming-units of a vancomycin-resistant Staphylococcus aureus strain in vitro, while not inducing resistance in a vancomycin-susceptible strain. Healing of a superficial wound in mice infected with the vancomycin-resistant S. aureus was significantly faster and more effective by irrigation with low-dose, dual-conjugated Van-PAMAM-AgNP dendrimer suspension than by irrigation with vancomycin in solution or a PAMAM-AgNP dendrimer suspension. Herewith, dual-conjugation of vancomycin together with AgNPs in heterofunctionalized PAMAM dendrimers fulfills the need for new, prolonged life-time antimicrobials killing resistant pathogens without inducing resistance in susceptible strains. Important for clinical translation, this better use of antibiotics can be achieved with currently approved and clinically applied antibiotics, provided suitable for amide-conjugation. Statement of significance Stringent regulations, high development costs and shorter effective life-times of new antimicrobials before the first resistant strains appear, make development of new antimicrobials commercially little attractive. Considering the steadily shortening effective life-time of novel antibiotics, development of novel antimicrobials should focus on infection-control strategies that kill infectious bacteria without inducing bacterial antimicrobial-resistance. The heterofunctionalized dual-antimicrobial dendrimers described in this study, killed vancomycin-resistant staphylococci, while not inducing resistance in a vancomycin-susceptible strain. Significantly, these heterofunctionalized dendrimers can be prepared with currently available antibiotics. Therewith they allow to make better use of existing antibiotics, provided amenable to amideconjugation and their pathway to clinical translation is short. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd

Research advances in drug therapy of endometriosis

Endometriosis is one of the most common benign gynecological disorders in reproductive-aged women. The major symptoms are chronic pelvic pain and infertility. Despite its profound impact on women’s health and quality of life, its pathogenesis has not been fully elucidated, it cannot be cured and the long-term use of drugs yields severe side effects and hinders fertility. This review aims to present the advances in pathogenesis and the newly reported lead compounds and drugs managing endometriosis. This paper investigated Genetic changes, estrogen-dependent inflammation induction, progesterone resistance, imbalance in proliferation and apoptosis, angiogenesis, lymphangiogenesis and neurogenesis, and tissue remodeling in its pathogenesis; and explored the pharmacological mechanisms, constitutive relationships, and application prospects of each compound in the text. To date, Resveratrol, Bay1316957, and bardoxifene were effective against lesions and pain in controlled animal studies. In clinical trials, Quinagolide showed no statistical difference with the placebo group; the results of phase II clinical trial of the IL-33 antibody have not been announced yet; clinical trial stage III of vilaprisan was suspended due to drug toxicity. Elagolix was approved for the treatment of endometriosis-related pain, but clinical studies of Elagolix for the pretreatment of patients with endometriosis to before In vitro fertilization treatment have not been fulfilled. The results of a clinical study of Linzagolix in patients with moderate to severe endometriosis-related pain have not been disclosed yet. Letrozole improved the fertility of patients with mild endometriosis. For endometriosis patients with infertility, oral GnRH antagonists and aromatase inhibitors are promising drugs, especially Elagolix and Letrozole

Application of eculizumab, a terminal complement inhibitor, in the management of atypical hemolytic uremic syndrome in a 14-month-old Chinese pediatric patient: a case report

Eculizumab, a recombined humanized monoclonal antibody which possesses high affinity for the complement protein C5, is a therapeutic agent utilized in the treatment of atypical hemolytic uremic syndrome (aHUS) by inhibiting the terminal complement complex C5b-9. In a pediatric patient with aHUS of 14 months, the administration of eculizumab therapy was accompanied by the inclusion of meningococcal vaccine as part of the national immunization program. Notably, no other antibiotics were administered prior to or during the course of eculizumab treatment. Moreover, there were no occurrences of infusion reactions or meningococcal infections observed throughout the course of treatment. Due to the presence of anti-factor H antibodies and insufficient recovery, glucocorticoids and eculizumab were administered at week 0 and week 1, followed by the initiation of mycophenolate mofetil (MMF) at a dosage of 250 mg (approximately 548 mg/m2) per day starting from Day 10. Due to the recovered of complement antibody after 8 doses of eculizumab, the therapeutic interval was extended from once every 3 weeks to once a month since 9th administration. We experienced and successfully treated a rare case of aHUS with eculizumab in a 14-month-old Chinese pediatric patient

Energy recovery transport design for PKU FEL

A SRF linac based free electron laser user facility is under developed at Peking University. Energy recovery Linac technology was chosen for increase of average electron beam current, hence, increase of the free electron laser power. In this paper we present a conceptual design of beam transport line which satisfies requirement of ERL. A chicane consisting of four identical bend magnets is selected for path length adjustment up to ?? 18 degree. R56 of both arcs of the beam line is adjustable for full bunch compression. ?2007 IEEE.EI

Clearance of ESKAPE Pathogens from Blood Using Bacterially Activated Macrophage Membrane-Coated Silicon Nanowires

Extracorporeal devices to cleanse blood from infecting bacteria are based upon bacterial capture to surfaces, but the current generation of capture devices has variable and inconclusive therapeutic efficacy. Here, a microfluidic device equipped with a Si capture surface with a highly periodic nanowired structure is designed. Nanowired Si surfaces are coated with macrophage membranes to benefit from the natural blood compatibility and ligand-receptor binding of macrophages. When macrophages are activated by uptake of Staphylococcus aureus or Escherichia coli, zeta potentials of activated macrophage membrane coatings become less negative than those of nonactivated ones, stimulating nonspecific bacterial capture. In addition, Toll-like receptors in bacterially activated membrane coatings on nanowired surfaces that are absent in nonactivated membrane coatings contribute to specific bacterial capture. These two factors, together with the maintenance of fluidity in activated membrane coatings, cause broad spectrum, high capture efficiencies of all six ESKAPE member pathogens, considered most threatening to human health. Surfaces with such broad-spectrum capture efficiencies have not been previously described, but are clinically most relevant because blood cleansing should start as soon as possible after a septic patient becomes symptomatic, when the causative bacterial strain is still unknown

Affinity cryo-electron microscopy: Methods development and applications

Single particle cryo-electron microscopy (cryo-EM) is an emerging powerful tool for structural studies of macromolecular assemblies. Although less concentrated and smaller amounts of samples are required for single particle cryo-EM compared to X-ray crystallography, it remains challenging to study specimens that are low-abundance, low-yield, or short-lived. The recent development of affinity grid techniques holds great promise to tackle these challenging samples by combining the sample purification and freezing on TEM grids steps in cryo-EM grid preparation into a single step, revolutionize the grid preparation of cryo-EM, and extend single particle cryo-EM to a routine structural biology tool to characterize structures of a broad spectrum of macromolecules. In my PhD study, I have established a new design of the affinity cryo-EM approach, cryo-SPIEM that applies a traditional pathogen diagnosis tool Solid Phase Immune Electron Microscopy (SPIEM) to the single particle cryo-EM method, and also systematically explored the applications of affinity EM approaches and the potentials of affinity cryo-EM approaches for near-atomic single particle 3-D reconstruction. The cryo-SPIEM approach provides an alternative, largely simplified and easier to use affinity grid that directly works with most native macromolecular complexes with established antibodies, and enables cryo-EM studies of native samples directly from cell cultures. The application of the affinity cryo-EM approach for high-resolution cryo-EM has been demonstrated successfully by solving a 6.3 Å structure of Tulane virus using the polylysine-based affinity grid, and a 2.6 Å structure of Tulane virus using the antibody-based affinity grid with a sample of low concentrations that defies standard cryo-EM study. Moreover, we have applied the affinity grid technique to investigate the interaction between Tulane virus and its cellular receptor Histo-blood group antigens, which revealed the potential roles of HBGA receptors in mediating genome release