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Objective: To assess the impact on patient experience scores of giving an ice pop (Popsicle, Good Humor-Breyers, Oakland, CA) to patients in a pediatric emergency department (ED)., Patients and Methods: A prospective two-center trial was conducted at a tertiary academic pediatric ED and a community ED from January 1, 2018, through March 31, 2018. The intervention arm gave an ice pop to all eligible patients 0 to 14 years of age on even-numbered days versus conventional practice on odd-numbered days. Press Ganey top box scores were then compared., Results: Of 4574 pediatric (0 to 14 years of age) patient visits, patient experience surveys were delivered to 1346 families (29.4%) and 152 were returned (11.3%). Eighty-four surveys were returned for even-numbered day visits and 68 for odd-numbered day visits. There was a significant increase in patient experience scores associated with ice pop administration days for questions that asked about doctor's concern for comfort 70.2% versus 57.4% (P=. 05), doctor's courtesy 76.2% versus 61.8% ( P =.04), and doctor taking time to listen 72.6% versus 57.4% ( P =.03)., Conclusion: A low-cost intervention resulted in significantly increased patient experience scores in select domains. Popsicle administration was a simple intervention which was easily instituted in both academic and community ED settings. Further study should explore the durability of the effect., (© 2020 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc.)

Case Presentation: A 48-year-old male who presented with signs and symptoms suggestive of an upper respiratory infection was seen at an urgent care, he had a negative chest radiograph and was discharged. With no other cases of coronavirus disease 2019 (COVID-19) in the state, the patient presented to the emergency department two days later with worsening shortness of breath., Discussion: There are a variety of findings on both chest radiograph and computed tomography of the chest that suggests COVID-19.

Analytical ultracentrifugation (AUC) is a first principles based method to determine absolute sedimentation coefficients and buoyant molar masses of macromolecules and their complexes, reporting on their size and shape in free solution. The purpose of this multi-laboratory study was to establish the precision and accuracy of basic data dimensions in AUC and validate previously proposed calibration techniques. Three kits of AUC cell assemblies containing radial and temperature calibration tools and a bovine serum albumin (BSA) reference sample were shared among 67 laboratories, generating 129 comprehensive data sets. These allowed for an assessment of many parameters of instrument performance, including accuracy of the reported scan time after the start of centrifugation, the accuracy of the temperature calibration, and the accuracy of the radial magnification. The range of sedimentation coefficients obtained for BSA monomer in different instruments and using different optical systems was from 3.655 S to 4.949 S, with a mean and standard deviation of (4.304 ± 0.188) S (4.4%). After the combined application of correction factors derived from the external calibration references for elapsed time, scan velocity, temperature, and radial magnification, the range of s-values was reduced 7-fold with a mean of 4.325 S and a 6-fold reduced standard deviation of ± 0.030 S (0.7%). In addition, the large data set provided an opportunity to determine the instrument-to-instrument variation of the absolute radial positions reported in the scan files, the precision of photometric or refractometric signal magnitudes, and the precision of the calculated apparent molar mass of BSA monomer and the fraction of BSA dimers. These results highlight the necessity and effectiveness of independent calibration of basic AUC data dimensions for reliable quantitative studies.

Recent reviews have focused on the structure and function of histone chaperones involved in different aspects of somatic cell chromatin metabolism. One of the most dramatic chromatin remodeling processes takes place immediately after fertilization and is mediated by egg histone storage chaperones. These include members of the nucleoplasmin (NPM2/NPM3), which are preferentially associated with histones H2A-H2B in the egg and the nuclear autoantigenic sperm protein (NASP) families. Interestingly, in addition to binding and providing storage to H3/H4 in the egg and in somatic cells, NASP has been shown to be a unique genuine chaperone for histone H1. This review revolves around the structural and functional roles of these two families of chaperones whose activity is modulated by their own post-translational modifications (PTMs), particularly phosphorylation. Beyond their important role in the remodeling of paternal chromatin in the early stages of embryogenesis, NPM and NASP members can interact with a plethora of proteins in addition to histones in somatic cells and play a critical role in processes of functional cell alteration, such as in cancer. Despite their common presence in the egg, these two histone chaperones appear to be evolutionarily unrelated. In contrast to members of the NPM family, which share a common monophyletic evolutionary origin, the different types of NASP appear to have evolved recurrently within different taxa.

MRE11-RAD50 is a key early response protein for processing DNA ends of broken chromosomes for repair, yet how RAD50 nucleotide dynamics regulate MRE11 nuclease activity is poorly understood. We report here that ATP binding and ATP hydrolysis cause a striking butterfly-like opening and closing of the RAD50 subunits, and each structural state has a dramatic functional effect on MRE11. RAD50-MRE11 has an extended conformation in solution when MRE11 is an active nuclease. However, ATP binding to RAD50 induces a closed conformation, and in this state MRE11 is an endonuclease. ATP hydrolysis opens the RAD50-MRE11 complex, and MRE11 maintains exonuclease activity. Thus, ATP hydrolysis is a molecular switch that converts MRE11 from an endonuclease to an exonuclease. We propose a testable model in which the open-closed transitions are used by RAD50-MRE11 to discriminate among DNA ends and drive the choice of recombination pathways.

Enterohemorrhagic Escherichia coli is a causative agent of gastrointestinal and diarrheal diseases. These pathogenic E. coli express a syringe-like protein machine, known as the type III secretion system (T3SS), used for the injection of virulence factors into the cytosol of the host epithelial cell. Breaching the epithelial plasma membrane requires formation of a translocation pore that contains the secreted protein EspD. Here we demonstrate that the N-terminal segment of EspD, encompassing residues 1-171, contains two amphipathic domains spanning residues 24-41 and 66-83, with the latter of these helices being critical for EspD function. Fluorescence and circular dichroism analysis revealed that, in solution, His₆-EspD₁₋₁₇₁ adopts a native disordered structure; however, on binding anionic small unilamellar vesicles composed of phosphatidylserine, His₆-EspD₁₋₁₇₁ undergoes a pH depended conformational change that increases the α-helix content of this protein approximately sevenfold. This change coincides with insertion of the region circumscribing Trp₄₇ into the hydrophobic core of the lipid bilayer. On the HeLa cell plasma membrane, His₆-EspD₁₋₁₇₁ forms a homodimer that is postulated to promote EspD-EspD oligomerization and pore formation. Complementation of ΔespD null mutant bacteria with an espDΔ66-83 gene showed that this protein was secreted but non-functional., (© 2011 Blackwell Publishing Ltd.)

NASP has been described as a histone H1 chaperone in mammals. However, the molecular mechanisms involved have not yet been characterized. Here, we show that this protein is not only present in mammals but is widely distributed throughout eukaryotes both in its somatic and testicular forms. The secondary structure of the human somatic version consists mainly of clusters of alpha-helices and exists as a homodimer in solution. The protein binds nonspecifically to core histone H2A-H2B dimers and H3-H4 tetramers but only forms specific complexes with histone H1. The formation of the NASP-H1 complexes is mediated by the N- and C-terminal domains of histone H1 and does not involve the winged helix domain that is characteristic of linker histones. In vitro chromatin reconstitution experiments show that this protein facilitates the incorporation of linker histones onto nucleosome arrays and hence is a bona fide linker histone chaperone.

We have previously characterized the interaction of nucleoplasmin with core histones and studied the possible involvement of this chaperone molecule in transcription. Here we study the interaction of nucleoplasmin with chromatin. We show that highly phosphorylated Xenopus laevis egg nucleoplasmin can unfold sperm and somatic chromatin in a way that involves the removal of chromosomal proteins from linker DNA regions without a stable interaction with the nucleosome. The complexes between egg nucleoplasmin and both somatic and sperm-specific linker proteins have been hydrodynamically characterized using sedimentation equilibrium in the analytical ultracentrifuge. The results are discussed within the context of the possible implication of nucleoplasmin in processes such as transcription and replication licensing which take place after egg fertilization at the onset of development.

Histone H2A ubiquitination is a bulky posttranslational modification that occurs at the vicinity of the binding site for linker histones in the nucleosome. Therefore, we took several experimental approaches to investigate the role of ubiquitinated H2A (uH2A) in the binding of linker histones. Our results showed that uH2A was present in situ in histone H1-containing nucleosomes. Notably in vitro experiments using nucleosomes reconstituted onto 167-bp random sequence and 208-bp (5 S rRNA gene) DNA fragments showed that ubiquitination of H2A did not prevent binding of histone H1 but it rather enhanced the binding of this histone to the nucleosome. We also showed that ubiquitination of H2A did not affect the positioning of the histone octamer in the nucleosome in either the absence or the presence of linker histones.

Anthracycline antibiotics are an important group of antitumor drugs widely used in cancer chemotherapy. However, despite the increasing interest in these chemotherapeutic agents, their mechanism of action is not yet completely understood. Here, we review what is currently known about the molecular mechanisms involved with special emphasis on the interaction of these drugs with chromatin and its constitutive components: DNA and histones. The evidence suggests that one very important component of the activity of these drugs is the result of these manifold interactions that lead to a chromatin unfolding and aggregation. This chromatin structural disruption is likely to interfere with the metabolic processes of DNA (replication and transcription) and it may play an important role in the apoptosis undergone by the cells upon treatment with these drugs., (Copyright 2004 Wiley Periodicals, Inc.)

Daunomycin is an anticancer drug that is well-known to interact with DNA in chromatin. Using a compositionally defined chicken erythrocyte chromatin fraction, we have obtained conclusive evidence that the drug is also able to interact with chromatin-bound linker histones without any noticeable binding to core histones. The drug can interact in an equal fashion with both histone H1 and H5 and to a greater extent with core histones H3/H4 and H2A/H2B as free proteins in solution. Thus, the binding of daunomycin to linker histones in the chromatin fiber is most likely due to the well-known higher accessibility of these histones to the surrounding environment of the fiber. Binding of daunomycin to linker histones appears to primarily involve the trypsin-resistant (winged-helix) domain of these proteins. The studies described here reveal the occurrence of a previously undisclosed mechanism for the antitumor activity of anthracycline drugs at the chromatin level.