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"White, Katharine"
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Dragonshadow
\"Sparring lovers Aliza and Alastair are fierce warriors who match wits, charm, and swords as they fight an epic war to save their world. The Battle of North Fields is over--or so Aliza Bentaine, now a Daired, fervently wants to believe. But rumors are spreading of an unseen monster ravaging the isolated Castle Selwyn on the northern border of the kingdom. When she and Alastair are summoned from their honeymoon by the mysterious Lord Selwyn, they must travel with their dragon Akarra through the Tekari-infested Old Wilds of Arle to answer his call. And they are not alone on this treacherous journey. Shadowing the dragonriders is an ancient evil, a harbinger of a dark danger of which the Worm was only a foretaste. And soon Aliza realizes the terrible truth: the real war is only beginning.\" -- (Source of summary not specified)
Book
First trimester medication abortion practice in the United States and Canada
We conducted a cross-sectional survey of abortion facilities from professional networks in the United States (US, n = 703) and Canada (n = 94) to estimate the prevalence of medication abortion practices in these settings and to look at regional differences. Administrators responded to questions on gestational limits, while up to five clinicians per facility reported on 2012 medication abortion practice. At the time of fielding, mifepristone was not approved in Canada. 383 (54.5%) US and 78 (83.0%) Canadian facilities participated. In the US, 95.3% offered first trimester medication abortion compared to 25.6% in Canada. While 100% of providers were physicians in Canada, just under half (49.4%) were advanced practice clinicians in the US, which was more common in Eastern and Western states. All Canadian providers used misoprostol; 85.3% with methotrexate. 91.4% of US providers used 200 mg of mifepristone and 800 mcg of misoprostol, with 96.7% reporting home misoprostol administration. More than three-quarters of providers in both countries required an in-person follow-up visit, generally with ultrasound. 87.7% of US providers routinely prescribed antibiotics compared to 26.2% in Canada. Nonsteroidal anti-inflammatory drugs were the most commonly reported analgesic, with regional variation in opioid narcotic prescription. In conclusion, medication abortion practice follows evidence-based guidelines in the US and Canada. Efforts to update practice based on the latest evidence for reducing in-person visits and increasing provision by advanced practice clinicians could strengthen these services and reduce barriers to access. Research is needed on optimal antibiotic and analgesic use.
Journal Article
Heartstone
\"A debut novel that retells Pride and Prejudice in a world where creatures [such as] dragons, hobgoblins, lamias, and gryphons are commonplace, Heartstone takes Austen's classic tale and turns it into something new\"-- Provided by publisher.
BOOK
Obesity downregulates lipid metabolism genes in first trimester placenta
Placentas of obese women have low mitochondrial β-oxidation of fatty acids (FA) and accumulate lipids in late pregnancy. This creates a lipotoxic environment, impairing placental efficiency. We hypothesized that placental FA metabolism is impaired in women with obesity from early pregnancy. We assessed expression of key regulators of FA metabolism in first trimester placentas of lean and obese women. Maternal fasting triglyceride and insulin levels were measured in plasma collected at the time of procedure. Expression of genes associated with FA oxidation (FAO; ACOX1, CPT2, AMPKα), FA uptake (LPL, LIPG, MFSD2A), FA synthesis (ACACA) and storage (PLIN2) were significantly reduced in placentas of obese compared to lean women. This effect was exacerbated in placentas of male fetuses. Placental ACOX1 protein was higher in women with obesity and correlated with maternal circulating triglycerides. The PPARα pathway was enriched for placental genes impacted by obesity, and PPARα antagonism significantly reduced
3
H-palmitate oxidation in 1
st
trimester placental explants. These results demonstrate that obesity and hyperlipidemia impact placental FA metabolism as early as 7 weeks of pregnancy.
Journal Article
Prominent features of the amino acid mutation landscape in cancer
Cancer can be viewed as a set of different diseases with distinctions based on tissue origin, driver mutations, and genetic signatures. Accordingly, each of these distinctions have been used to classify cancer subtypes and to reveal common features. Here, we present a different analysis of cancer based on amino acid mutation signatures. Non-negative Matrix Factorization and principal component analysis of 29 cancers revealed six amino acid mutation signatures, including four signatures that were dominated by either arginine to histidine (Arg>His) or glutamate to lysine (Glu>Lys) mutations. Sample-level analyses reveal that while some cancers are heterogeneous, others are largely dominated by one type of mutation. Using a non-overlapping set of samples from the COSMIC somatic mutation database, we validate five of six mutation signatures, including signatures with prominent arginine to histidine (Arg>His) or glutamate to lysine (Glu>Lys) mutations. This suggests that our classification of cancers based on amino acid mutation patterns may provide avenues of inquiry pertaining to specific protein mutations that may generate novel insights into cancer biology.
Journal Article
fluorophore ligase for site-specific protein labeling inside living cells
Biological microscopy would benefit from smaller alternatives to green fluorescent protein for imaging specific proteins in living cells. Here we introduce PRIME (PRobe Incorporation Mediated by Enzymes), a method for fluorescent labeling of peptide-fused recombinant proteins in living cells with high specificity. PRIME uses an engineered fluorophore ligase, which is derived from the natural Escherichia coli enzyme lipoic acid ligase (LplA). Through structure-guided mutagenesis, we created a mutant ligase capable of recognizing a 7-hydroxycoumarin substrate and catalyzing its covalent conjugation to a transposable 13-amino acid peptide called LAP (LplA Acceptor Peptide). We showed that this fluorophore ligation occurs in cells in 10 min and that it is highly specific for LAP fusion proteins over all endogenous mammalian proteins. By genetically targeting the PRIME ligase to specific subcellular compartments, we were able to selectively label spatially distinct subsets of proteins, such as the surface pool of neurexin and the nuclear pool of actin.
Journal Article
Intracellular pH dynamics respond to extracellular matrix stiffening and mediate vasculogenic mimicry through β-catenin
Dysregulated intracellular pH (pHi) dynamics and an altered tumor microenvironment have emerged as drivers of cancer cell phenotypes. However, the molecular integration between the physical properties of the microenvironment and dynamic intracellular signaling responses remains unclear. Here, we identify a mechanistic link between extracellular matrix (ECM) stiffness and pHi dynamics in driving vasculogenic mimicry (VM), an aggressive cancer phenotype associated with poor prognosis. We performed single-cell imaging of pHi in lung and breast metastatic cell lines cultured on tunable-stiffness hydrogel systems. We used two tunable-stiffness hydrogel systems to independently model ECM stiffness induced by increased protein secretion (Matrigel) and increased protein crosslinking (Hyaluronic acid gels). We show that increased ECM stiffness lowers single-cell pHi in both lung and breast metastatic cell lines. We also observed that stiff ECM promotes a distinct morphological phenotype called vasculogenic mimicry (VM). Importantly, we show that low pHi is a necessary mediator of VM, as raising pHi on stiff ECM reduces VM phenotypes. We also find that lowering pHi on soft ECM was sufficient to induce VM in the absence of extracellular stiffening. We characterized β-catenin as a pH-dependent molecular mediator of VM, where stiffness-driven increases in β-catenin abundance can be overridden by high pHi, which destabilizes β-catenin to reduce VM on stiff ECM. In contrast, the VM-associated transcription factor FOXC2 is activated by ECM stiffness but is insensitive to pHi, and its activity alone is insufficient to maintain VM at high pHi when β-catenin is lost. We uncover a novel mechanotransduction axis in which ECM stiffness regulates intracellular pH to drive β-catenin-induced VM. We also show pHi dynamics can override mechanosensitive cell responses to the extracellular microenvironment. Thus, our work positions pHi as an integrator of mechanotransduction in cancer, suggesting a new framework for therapeutically targeting pHi in cancer and perhaps in other diseases driven by ECM remodeling.
Journal Article
Imaging Trans-Cellular Neurexin-Neuroligin Interactions by Enzymatic Probe Ligation
Neurexin and neuroligin are transmembrane adhesion proteins that play an important role in organizing the neuronal synaptic cleft. Our lab previously reported a method for imaging the trans-synaptic binding of neurexin and neuroligin called BLINC (Biotin Labeling of INtercellular Contacts). In BLINC, biotin ligase (BirA) is fused to one protein while its 15-amino acid acceptor peptide substrate (AP) is fused to the binding partner. When the two fusion proteins interact across cellular junctions, BirA catalyzes the site-specific biotinylation of AP, which can be read out by staining with streptavidin-fluorophore conjugates. Here, we report that BLINC in neurons cannot be reproduced using the reporter constructs and labeling protocol previously described. We uncover the technical reasons for the lack of reproducibilty and then re-design the BLINC reporters and labeling protocol to achieve neurexin-neuroligin BLINC imaging in neuron cultures. In addition, we introduce a new method, based on lipoic acid ligase instead of biotin ligase, to image trans-cellular neurexin-neuroligin interactions in human embryonic kidney cells and in neuron cultures. This method, called ID-PRIME for Interaction-Dependent PRobe Incorporation Mediated by Enzymes, is more robust than BLINC due to higher surface expression of lipoic acid ligase fusion constructs, gives stronger and more localized labeling, and is more versatile than BLINC in terms of signal readout. ID-PRIME expands the toolkit of methods available to study trans-cellular protein-protein interactions in living systems.
Journal Article
Site-specific protein labeling using PRIME and chelation-assisted click chemistry
This protocol describes an efficient method to site-specifically label cell-surface or purified proteins with chemical probes in two steps: probe incorporation mediated by enzymes (PRIME) followed by chelation-assisted copper-catalyzed azide-alkyne cycloaddition (CuAAC). In the PRIME step,
Escherichia coli
lipoic acid ligase (LplA) site-specifically attaches a picolyl azide (pAz) derivative to a 13-aa recognition sequence that has been genetically fused onto the protein of interest. Proteins bearing pAz are chemoselectively derivatized with an alkyne-probe conjugate by chelation-assisted CuAAC in the second step. We describe herein the optimized protocols to synthesize pAz to perform PRIME labeling and to achieve CuAAC derivatization of pAz on live cells, fixed cells and purified proteins. Reagent preparations, including synthesis of pAz probes and expression of LplA, take 12 d, whereas the procedure for performing site-specific pAz ligation and CuAAC on cells or on purified proteins takes 40 min–3 h.
Journal Article