Publications by authors named "Clarke O"

Spheroids serve as the building blocks for three-dimensional (3D) bioprinted tissue patches. When larger than 500 μm, the desired size for 3D bioprinting, they tend to have a hypoxic core with necrotic cells. Therefore, it is critical to assess the viability of spheroids in order to ensure the successful fabrication of high-viability patches.

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The glycoprotein hormones of humans, produced in the pituitary and acting through receptors in the gonads to support reproduction and in the thyroid gland for metabolism, have co-evolved from invertebrate counterparts. These hormones are heterodimeric cystine-knot proteins; and their receptors bind the cognate hormone at an extracellular domain and transmit the signal of this binding through a transmembrane domain that interacts with a heterotrimeric G protein. Structures determined for the human receptors as isolated for cryogenic electron microscopy (cryo-EM) are all monomeric despite compelling evidence for their functioning as dimers.

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It is now possible to generate large volumes of high-quality images of biomolecules at near-atomic resolution and in near-native states using cryogenic electron microscopy/electron tomography (Cryo-EM/ET). However, the precise annotation of structures like filaments and membranes remains a major barrier towards applying these methods in high-throughput. To address this, we present TARDIS (ransformer-bsed apid imensionless nstance egmentation), a machine-learning framework for fast and accurate annotation of micrographs and tomograms.

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Article Synopsis
  • Malignant hyperthermia (MH) is a serious genetic condition triggered by certain anesthetics, particularly affecting a protein called RyR1.
  • Dantrolene is the main treatment for MH, but how it works and where it binds on RyR1 was previously unclear.
  • This study used cryo-electron microscopy to detail how dantrolene and another agent bind to RyR1, revealing that dantrolene's binding requires ATP or ADP and can close the channel, highlighting its potential role in sensing energy levels in cells.
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Upon stimulation of membrane receptors, nicotinic acid adenine dinucleotide phosphate (NAADP) is formed as second messenger within seconds and evokes Ca signaling in many different cell types. Here, to directly stimulate NAADP signaling, MASTER-NAADP, a Membrane permeAble, STabilized, bio-rEversibly pRotected precursor of NAADP is synthesized and release of its active NAADP mimetic, benzoic acid C-nucleoside, 2'-phospho-3'F-adenosine-diphosphate, by esterase digestion is confirmed. In the presence of NAADP receptor HN1L/JPT2 (hematological and neurological expressed 1-like protein, HN1L, also known as Jupiter microtubule-associated homolog 2, JPT2), this active NAADP mimetic releases Ca and increases the open probability of type 1 ryanodine receptor.

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Aims: The aim is to investigate the effect of alvimopan on postoperative ileus and length of hospital stay in patients undergoing bowel resection.

Methods: The PRISMA statement standards were followed to conduct a systematic review and meta-analysis. The available literature was searched to identify all studies comparing alvimopan with no alvimopan in patients undergoing bowel resection.

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Article Synopsis
  • - HCN1-4 channels are essential for regulating heart and brain cell activity, and their dysfunction can lead to serious health issues like epilepsy and chronic pain, highlighting the need for targeted treatments.
  • - Researchers determined the cryo-EM structure of HCN4 in complex with ivabradine, showing that the drug binds within the channel's open pore and identifies key amino acids that play a role in this interaction.
  • - The study finds that ivabradine blocks ion flow by electrostatic repulsion, a process similar to how certain other compounds work, providing new insights into how this drug affects channel activity.
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Proteins and other biomolecules form dynamic macromolecular machines that are tightly orchestrated to move, bind, and perform chemistry. Cryo-electron microscopy (cryo-EM) can access the intrinsic heterogeneity of these complexes and is therefore a key tool for understanding mechanism and function. However, 3D reconstruction of the resulting imaging data presents a challenging computational problem, especially without any starting information, a setting termed ab initio reconstruction.

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Targeted recruitment of E3 ubiquitin ligases to degrade traditionally undruggable proteins is a disruptive paradigm for developing new therapeutics. Two salient limitations are that <2% of the ~600 E3 ligases in the human genome have been exploited to produce proteolysis targeting chimeras (PROTACs), and the efficacy of the approach has not been demonstrated for a vital class of complex multi-subunit membrane proteins- ion channels. NEDD4-1 and NEDD4-2 are physiological regulators of myriad ion channels, and belong to the 28-member HECT (homologous to E6AP C-terminus) family of E3 ligases with widespread roles in cell/developmental biology and diverse diseases including various cancers, immunological and neurological disorders, and chronic pain.

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Ionic liquids (ILs) nanostructuring at electrified interfaces is of both fundamental and practical interest as these materials are increasingly gaining prominence in energy storage and conversion processes. However, much remains unresolved about IL potential-controlled (re)organization under highly polarized interfaces, mostly due to the difficulty of selectively probing both the distal and proximal surface layers of adsorbed ions. In this work, the structural dynamics of the innermost layer (<10 nm from the surface) were independently interrogated from that of the ionic layers in the sub-surface region (>100 nm from the surface), using an infrared (IR) spectroscopy approach.

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Article Synopsis
  • Choline is a crucial nutrient needed by the body for processes like building cell membranes and neurotransmission, with the brain having the highest demand for it.
  • The protein FLVCR2, found in cells at the blood-brain barrier, is identified as the main transporter for choline into the brain, unlike another related protein, FLVCR1, which is not as active there.
  • Research includes structural analysis of FLVCR2 using cryo-electron microscopy, which shows how choline binds and is transported, offering potential insights for delivering therapies into the brain more effectively.
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The human calcium-sensing receptor (CaSR) detects fluctuations in the extracellular Ca concentration and maintains Ca homeostasis. It also mediates diverse cellular processes not associated with Ca balance. The functional pleiotropy of CaSR arises in part from its ability to signal through several G-protein subtypes.

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Unlabelled: WHAT IS KNOWN ON THE SUBJECT?: Mental health care can be delivered remotely through video and telephone consultations. Remote consultations may be cheaper and more efficient than in person consultations.

What The Paper Adds To Existing Knowledge: Accessing community mental health care through remote consultations is perceived as not possible or beneficial for all service users.

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Choline is an essential nutrient that the human body needs in vast quantities for cell membrane synthesis, epigenetic modification, and neurotransmission. The brain has a particularly high demand for choline, but how it enters the brain has eluded the field for over fifty years. The MFS transporter FLVCR1 was recently determined to be a choline transporter, and while this protein is not highly expressed at the blood-brain barrier (BBB), its relative FLVCR2 is.

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Thyroglobulin must pass endoplasmic reticulum (ER) quality control to become secreted for thyroid hormone synthesis. Defective thyroglobulin, blocked in trafficking, can cause hypothyroidism. Thyroglobulin is a large protein (~2750 residues) spanning regions I-II-III plus a C-terminal cholinesterase-like domain.

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Peptidoglycan (PG) is an essential structural component of the bacterial cell wall that is synthetized during cell division and elongation. PG forms an extracellular polymer crucial for cellular viability, the synthesis of which is the target of many antibiotics. PG assembly requires a glycosyltransferase (GT) to generate a glycan polymer using a Lipid II substrate, which is then crosslinked to the existing PG via a transpeptidase (TP) reaction.

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In situ investigations of electrocatalytic processes of increasing societal interest such as the nitrogen reduction reaction (NRR) require aggressive experimental conditions that are not readily compatible with surface sensitive techniques such as attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). A method for performing ATR-SEIRAS studies at very negative potentials where conventional IR-active films delaminate and fail is reported. The method relies on a thin film of very robust boron-doped diamond deposited on a micromachined Si wafer, which provides extended mid-IR transparency at long wavelengths.

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Background: To provide just equity in academic exchange, as well as to reduce prohibitive travel cost and address environmental concerns, the past paradigm of international student exchange has fundamentally shifted from one directional travel to mutually beneficial bidirectional remote communication between students all over the globe. Current analysis aims to quantify cultural competency and evaluate academic outcomes.

Methods: Sixty students half from the US and half from Rwanda grouped in teams of 4 engaged in a nine-month project-focused relationship.

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Aims: The care of patients undergoing long-term urethral catheterization is frequently complicated by Proteus mirabilis infection. This organism forms dense, crystalline biofilms, which block catheters leading to serious clinical conditions. However, there are currently no truly effective approaches to control this problem.

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Coronavirus disease (COVID-19) is a contagious respiratory disease caused by the SARS-CoV-2 virus. The clinical phenotypes are variable, ranging from spontaneous recovery to serious illness and death. On March 2020, a global COVID-19 pandemic was declared by the World Health Organization (WHO).

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Chlorhexidine (CHD) is a cationic biocide used ubiquitously in healthcare settings. , an important pathogen of the catheterized urinary tract, and isolates of this species are often described as "resistant" to CHD-containing products used for catheter infection control. To identify the mechanisms underlying reduced CHD susceptibility in , we subjected the CHD tolerant clinical isolate RS47 to random transposon mutagenesis and screened for mutants with reduced CHD minimum inhibitory concentrations (MICs).

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A family of leucine-rich-repeat-containing G-protein-coupled receptors (LGRs) mediate diverse physiological responses when complexed with their cognate ligands. LGRs are present in all metazoan animals. In humans, the LGR ligands include glycoprotein hormones (GPHs) chorionic gonadotropin (hCG), luteinizing hormone, follicle-stimulating hormone (hFSH), and thyroid-stimulating hormone (hTSH).

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The primary functional units of the thyroid gland are follicles of various sizes comprised of a monolayer of epithelial cells (thyrocytes) surrounding an apical extracellular cavity known as the follicle lumen. In the normal thyroid gland, the follicle lumen is filled with secreted protein (referred to as colloid), comprised nearly exclusively of thyroglobulin with a half-life ranging from days to weeks. At the cellular boundary of the follicle lumen, secreted thyroglobulin becomes iodinated, resulting from the coordinated activities of enzymes localized to the thyrocyte apical plasma membrane.

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