LIGAND ARCHITECTURE EFFECTS UPON PRIMARY COPPER-DIOXYGEN ADDUCT CHEMISTRY

The investigation into the chemical/physical properties of synthetic copper complexes provide fundamental insights into the understanding of the enzyme chemistry overviewed in this dissertation. In Chapter 1, copper monooxygenases and oxidases involved in C–H/O–H bond oxidation are introduced, along with biological functions, coordination environment of their metal active sites and their proposed mechanisms. Recent investigations of various synthetic oxygen-derived copper intermediates, including their characteristics and reactivity, are described. Possible reaction mechanisms are also highlighted by comparison to aqueous O2-reduction chemistry. In Chapter 2, with the goal of understanding the mechanism of phenol oxidation by mononuclear cupric superoxo species, kinetic studies were performed with the reaction of a new copper(II) superoxo complex [(DMM-tmpa)CuII(O2•¬–)]+ and a series of para-substituted-2,6-di-tert-butylphenols (p-X-DTBP’s) affording 2,6-di-tert-butyl-1,4-benzoquinones (DTBQ’s). Significant deuterium kinetic isotope effects (KIE's) and a positive correlation of second-order-rate constants (k2’s) compared to rate constants for p-X-DTBP’s plus cumylperoxyl radical reactions indicate a mechanism involves rate-limiting hydrogen atom transfer (HAT). Product analyses, 18O-labeling experiments, and separate reactivity employing the 2,4,6-tri-tert-butylphenoxyl radical provide further mechanistic insights. Chapter 3 reports the first example of sulfur-ligated mononuclear superoxo species which mimics the putative CuII(O2•–) active species of the peptidylglycine-α-hydroxylating monooxygenase, PHM. This complex exhibits enhanced reactivity towards both O-H and C-H substrates in comparison to close analogues [(L)CuII(O2•–)]+, where L contains only nitrogen donor atoms. Cu-S(thioether) ligation with its weaker donor ability (relative to an N-donor) are demonstrated by comparisons to the chemistry of analogue compounds. Chapter 4 provides the coordination chemistry and reactivity study of primary CuI/O2 species featuring an intramolecular hydrogen bonding substituent, (XBA)CuII(O2●–) (XS). The stability of XS compounds are ascribed to internal H-bond, from the secondary coordination sphere, to the proximal superoxide ‘O’ atom. Direct evidence for hydrogen atom transfer from phenol substrates by XS complexes was obtained, and enhanced reactivity of copper(II) superoxo complexes possessing electron-withdrawing groups (i.e., X) compared with other CuII(O2●–) analogues was observed. This behavior is discussed and correlated to the H-bonding ability of the XBA ligands and the copper ion centered redox behavior for varying XS complexes. In Chapter 5, we describe an overview of the copper proteins with respect to their preference for tautomeric histidine binding sites (δNHis vs εNHis) and a unique histidine-chelated ligand environment. Newly designed copper-histidine complexes are introduced, which possess ligands mimicking the copper center of certain enzymes. Dioxygen-derived copper species are determined to be (trans-peroxo)CuII2 and (bis-μ-oxo)CuIII2 complexes based on spectroscopic studies

Multiwavelength observations of the black hole transient XTE J1752-223 during its 2010 outburst decay

Galactic black hole transients show many interesting phenomena during outburst decays. We present simultaneous X-ray (RXTE, Swift, and INTEGRAL), and optical/near-infrared (O/NIR) observations (SMARTS), of the X-ray transient, XTE J1752-223 during its outburst decay in 2010. The multi- wavelength observations of 150 days in 2010 cover the transition from soft to hard spectral state. The evolution of ATCA/VLBI radio observations are shown to confirm the compact jet appearance. The source shows flares in O/NIR during changes in X-ray and radio properties. One of those flares is bright and long, and starts about 20 days after the transition in timing. Other, smaller flares occur along with the transition in timing and increase in power-law flux, and also right after the detection of the core with VLBI. Furthermore, using the simultaneous broadband X-ray spectra including IN- TEGRAL, we found that a high energy cut-off is necessary with a folding energy at around 250 keV around the time that the compact jet is forming. The broad band spectrum can also be fitted equally well with a Comptonization model. In addition, using photoelectric absorption edges in the XMM– Newton RGS X-ray spectra and the extinction of red clump giants in the direction of the source, we found a lower limit on the distance of > 5 kpc

Long-term glycemic variability and risk of adverse outcomes: a systematic review and meta-analysis

OBJECTIVE: Glycemic variability is emerging as a measure of glycemic control, which may be a reliable predictor of complications. This systematic review and meta-analysis evaluates the association between HbA1c variability and micro- and macrovascular complications and mortality in type 1 and type 2 diabetes. RESEARCH DESIGN AND METHODS: Medline and Embase were searched (2004–2015) for studies describing associations between HbA1c variability and adverse outcomes in patients with type 1 and type 2 diabetes. Data extraction was performed independently by two reviewers. Random-effects meta-analysis was performed with stratification according to the measure of HbA1c variability, method of analysis, and diabetes type. RESULTS: Seven studies evaluated HbA1c variability among patients with type 1 diabetes and showed an association of HbA1c variability with renal disease (risk ratio 1.56 [95% CI 1.08–2.25], two studies), cardiovascular events (1.98 [1.39–2.82]), and retinopathy (2.11 [1.54–2.89]). Thirteen studies evaluated HbA1c variability among patients with type 2 diabetes. Higher HbA1c variability was associated with higher risk of renal disease (1.34 [1.15–1.57], two studies), macrovascular events (1.21 [1.06–1.38]), ulceration/gangrene (1.50 [1.06–2.12]), cardiovascular disease (1.27 [1.15–1.40]), and mortality (1.34 [1.18–1.53]). Most studies were retrospective with lack of adjustment for potential confounders, and inconsistency existed in the definition of HbA1c variability. CONCLUSIONS: HbA1c variability was positively associated with micro- and macrovascular complications and mortality independently of the HbA1c level and might play a future role in clinical risk assessment

Minimising the impact of scale-dependent galaxy bias on the joint cosmological analysis of large scale structures

We present a mitigation strategy to reduce the impact of non-linear galaxy bias on the joint `$3 \times 2$pt' cosmological analysis of weak lensing and galaxy surveys. The $\Psi$-statistics that we adopt are based on Complete Orthogonal Sets of E/B Integrals (COSEBIs). As such they are designed to minimise the contributions to the observable from the smallest physical scales where models are highly uncertain. We demonstrate that $\Psi$-statistics carry the same constraining power as the standard two-point galaxy clustering and galaxy-galaxy lensing statistics, but are significantly less sensitive to scale-dependent galaxy bias. Using two galaxy bias models, motivated by halo-model fits to data and simulations, we quantify the error in a standard $3 \times 2$pt analysis where constant galaxy bias is assumed. Even when adopting conservative angular scale cuts, that degrade the overall cosmological parameter constraints, we find of order $1 \sigma$ biases for Stage III surveys on the cosmological parameter $S_8 = \sigma_8(\Omega_{\rm m}/0.3)^{\alpha}$. This arises from a leakage of the smallest physical scales to all angular scales in the standard two-point correlation functions. In contrast, when analysing $\Psi$-statistics under the same approximation of constant galaxy bias, we show that the bias on the recovered value for $S_8$ can be decreased by a factor of $\sim 2$, with less conservative scale cuts. Given the challenges in determining accurate galaxy bias models in the highly non-linear regime, we argue that $3 \times 2$pt analyses should move towards new statistics that are less sensitive to the smallest physical scales.Comment: 14 pages, 13 figures, accepted to be published in MNRA

Chromosomal instability in untreated primary prostate cancer as an indicator of metastatic potential.

BackgroundMetastatic prostate cancer (PC) is highly lethal. The ability to identify primary tumors capable of dissemination is an unmet need in the quest to understand lethal biology and improve patient outcomes. Previous studies have linked chromosomal instability (CIN), which generates aneuploidy following chromosomal missegregation during mitosis, to PC progression. Evidence of CIN includes broad copy number alterations (CNAs) spanning > 300 base pairs of DNA, which may also be measured via RNA expression signatures associated with CNA frequency. Signatures of CIN in metastatic PC, however, have not been interrogated or well defined. We examined a published 70-gene CIN signature (CIN70) in untreated and castration-resistant prostate cancer (CRPC) cohorts from The Cancer Genome Atlas (TCGA) and previously published reports. We also performed transcriptome and CNA analysis in a unique cohort of untreated primary tumors collected from diagnostic prostate needle biopsies (PNBX) of localized (M0) and metastatic (M1) cases to determine if CIN was linked to clinical stage and outcome.MethodsPNBX were collected from 99 patients treated in the VA Greater Los Angeles (GLA-VA) Healthcare System between 2000 and 2016. Total RNA was extracted from high-grade cancer areas in PNBX cores, followed by RNA sequencing and/or copy number analysis using OncoScan. Multivariate logistic regression analyses permitted calculation of odds ratios for CIN status (high versus low) in an expanded GLA-VA PNBX cohort (n = 121).ResultsThe CIN70 signature was significantly enriched in primary tumors and CRPC metastases from M1 PC cases. An intersection of gene signatures comprised of differentially expressed genes (DEGs) generated through comparison of M1 versus M0 PNBX and primary CRPC tumors versus metastases revealed a 157-gene "metastasis" signature that was further distilled to 7-genes (PC-CIN) regulating centrosomes, chromosomal segregation, and mitotic spindle assembly. High PC-CIN scores correlated with CRPC, PC-death and all-cause mortality in the expanded GLA-VA PNBX cohort. Interestingly, approximately 1/3 of M1 PNBX cases exhibited low CIN, illuminating differential pathways of lethal PC progression.ConclusionsMeasuring CIN in PNBX by transcriptome profiling is feasible, and the PC-CIN signature may identify patients with a high risk of lethal progression at the time of diagnosis

Contribution of Resistance-Nodulation-Cell Division Efflux Systems to Antibiotic Resistance and Biofilm Formation in Acinetobacter baumannii

International audienceABSTRACT : Acinetobacter baumannii is a nosocomial pathogen of increasing importance due to its multiple resistance to antibiotics and ability to survive in the hospital environment linked to its capacity to form biofilms. To fully characterize the contribution of AdeABC, AdeFGH, and AdeIJK resistance-nodulation-cell division (RND)-type efflux systems to acquired and intrinsic resistance, we constructed, from an entirely sequenced susceptible A. baumannii strain, a set of isogenic mutants overexpressing each system following introduction of a point mutation in their cognate regulator or a deletion for the pump by allelic replacement. Pairwise comparison of every derivative with the parental strain indicated that AdeABC and AdeFGH are tightly regulated and contribute to acquisition of antibiotic resistance when overproduced. AdeABC had a broad substrate range, including β-lactams, fluoroquinolones, tetracyclines-tigecycline, macrolides-lincosamides, and chloramphenicol, and conferred clinical resistance to aminoglycosides. Importantly, when combined with enzymatic resistance to carbapenems and aminoglycosides, this pump contributed in a synergistic fashion to the level of resistance of the host. In contrast, AdeIJK was expressed constitutively and was responsible for intrinsic resistance to the same major drug classes as AdeABC as well as antifolates and fusidic acid. Surprisingly, overproduction of AdeABC and AdeIJK altered bacterial membrane composition, resulting in decreased biofilm formation but not motility. Natural transformation and plasmid transfer were diminished in recipients overproducing AdeABC. It thus appears that alteration in the expression of efflux systems leads to multiple changes in the relationship between the host and its environment, in addition to antibiotic resistance.IMPORTANCE: Increased expression of chromosomal genes for RND-type efflux systems plays a major role in bacterial multidrug resistance. Acinetobacter baumannii has recently emerged as an important human pathogen responsible for epidemics of hospital-acquired infections. Besides its remarkable ability to horizontally acquire resistance determinants, it has a broad intrinsic resistance due to low membrane permeability, endogenous resistance genes, and antibiotic efflux. The study of isogenic mutants from a susceptible A. baumannii clinical isolate overproducing or deleted for each of the three major RND-type pumps demonstrated their major contribution to intrinsic resistance and to the synergism between overproduction of an efflux system and acquisition of a resistance gene. We have also shown that modulation of expression of the structural genes for the efflux systems results in numerous alterations in membrane-associated cellular functions, in particular, in a decrease in biofilm formation and resistance gene acquisition

Radiative Decay Rate and Branching Fractions of MgF

We report measured and calculated values of radiative decay rates and vibrational branching fractions for the A$^2\Pi$ state of MgF. The decay rate measurements use time-correlated single photon counting with roughly 1% total uncertainty. Branching-fraction measurements are performed using two calibrated imaging systems to achieve few percent total uncertainty. We use the highly accurate multireference relativistic ab initio methods to calculate the Franck-Condon factors and transition dipole moments required to determine the decay rates and the branching fractions. The measurements provide a precision benchmark for testing the accuracy of the molecular structure calculations. The determination of the decay rate and vibrational branching fractions can be used to inform future optical cycling and laser cooling schemes for the MgF molecule

Consumer Decision Making and Aging: Current Knowledge and Future Directions

We review existing knowledge about older consumers and decision making. We develop a conceptual framework that incorporates the notion of fit between individual characteristics, task demands and the contextual environment. When the fit is high, older consumers use their considerable knowledge and experience to compensate for the impact of any age‐related changes in abilities and resources. When the fit is relatively low, older consumers feel increased need to adapt their decision making processes. We discuss these consumer adaptations and propose a number of research questions related to the processes underlying them in order to contribute to a better understanding of how they can lead to more effective consumer decision making for older adults. We further consider some pragmatic implications of the adaptations for marketing management and public policy.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141554/1/jcpy2.pd

Design of MARQUIS2: study protocol for a mentored implementation study of an evidence-based toolkit to improve patient safety through medication reconciliation.

BackgroundThe first Multi-center Medication Reconciliation Quality Improvement Study (MARQUIS1) demonstrated that implementation of a medication reconciliation best practices toolkit decreased total unintentional medication discrepancies in five hospitals. We sought to implement the MARQUIS toolkit in more diverse hospitals, incorporating lessons learned from MARQUIS1.MethodsMARQUIS2 is a pragmatic, mentored implementation QI study which collected clinical and implementation outcomes. Sites implemented a revised toolkit, which included interventions from these domains: 1) best possible medication history (BPMH)-taking; 2) discharge medication reconciliation and patient/caregiver counseling; 3) identifying and defining clinician roles and responsibilities; 4) risk stratification; 5) health information technology improvements; 6) improved access to medication sources; 7) identification and correction of real-time discrepancies; and, 8) stakeholder engagement. Eight hospitalists mentored the sites via one site visit and monthly phone calls over the 18-month intervention period. Each site's local QI team assessed opportunities to improve, implemented at least one of the 17 toolkit components, and accessed a variety of resources (e.g. implementation manual, webinars, and workshops). Outcomes to be assessed will include unintentional medication discrepancies per patient.DiscussionA mentored multi-center medication reconciliation QI initiative using a best practices toolkit was successfully implemented across 18 medical centers. The 18 participating sites varied in size, teaching status, location, and electronic health record (EHR) platform. We introduce barriers to implementation and lessons learned from MARQUIS1, such as the importance of utilizing dedicated, trained medication history takers, simple EHR solutions, clarifying roles and responsibilities, and the input of patients and families when improving medication reconciliation

Twin Family Registries Worldwide : An Important Resource for Scientific Research

Much progress has been made in twin research since our last special issue on twin registries (Hur, Y.-M., & Craig, J. M. (2013). Twin Research and Human Genetics, 16, 1-12.). This special issue provides an update on the state of twin family registries around the world. This issue includes 61 papers on twin family registries from 25 countries, of which 3 describe consortia based on collaborations of several twin family registries. The articles included in this issue discuss the establishment and maintenance of twin registries, recruitment strategies, methods of zygosity assessment, research aims and major findings from twin family cohorts, as well as other important topics related to twin studies. The papers amount to approximately 1.3 million monozygotic, dizygotic twins and higher order multiples and their family members who participate in twin studies around the world. Nine new twin family registries have been established across the world since our last issue, which demonstrates that twin registers are increasingly important in studies of the determinants and correlates of complex traits from disease susceptibility to healthy development.Non peer reviewe